Top CNC machining factories achieve flawless workpieces because they have encountered numerous CNC machining defects. These experiences have taught operators how to better shape the desired forms. Understanding CNC machining defects is not entirely negative; it can significantly aid future machining operations.

Prototool, a leading CNC machining factory in China, has summarized the causes and solutions for CNC machining defects based on past experiences. This serves two purposes: to facilitate industry knowledge exchange and to demonstrate our expertise to our clients.

Overcutting in Workpieces

Die Ursachen:

1. Tool springing due to insufficient tool strength, excessive length, or small size.
2. Improper operation by the operator.
3. Uneven cutting allowance (e.g., 0.5 on curved side surfaces, 0.15 on the bottom).
4. Inappropriate cutting parameters (e.g., excessive tolerance, too fast SF settings).

Improvements:

1. Tool Usage Principle: Prefer larger and shorter tools where possible.
2. Implement a chamfering program to maintain uniform allowance (consistent allowance for side and bottom surfaces).
3. Adjust cutting parameters reasonably, rounding large allowance corners.
4. Utilize the machine’s SF function, allowing operators to fine-tune speed for optimal cutting.

Centering Issues

Die Ursachen:

1. Inaccuracy in manual operation by the operator.
2. Burrs around the mold.
3. Magnetic centering rods.
4. Non-vertical sides of the mold.

Improvements:

1. Manual operations should be carefully checked and repeated, centering at the same point and height as much as possible.
2. Remove burrs around the mold with an oilstone or file, clean with a rag, and confirm by hand.
3. Demagnetize the centering rod before using it on the mold (use ceramic rods or others).
4. Use a dial indicator to check the mold’s verticality (discuss solutions with the fitter if there’s significant verticality error).

Tool Setting Issues

Die Ursachen:

1. Inaccuracy in manual operation by the operator.
2. Incorrect tool clamping.
3. Errors in the tool tip on the fly cutter (inherent inaccuracies in the fly cutter).
4. Discrepancies between R-cutters, flat-bottom cutters, and fly cutters.

Improvements:

1. Carefully repeat manual operations, ensuring tool setting is consistent.
2. Clean the tool clamp with an air gun or rag before clamping.
3. When measuring the tool rod or base surface, use a single cutter tip on the fly cutter.
4. Create a separate tool setting program to avoid discrepancies between R-cutters, flat-bottom cutters, and fly cutters.

CNC Crash – Programming

Die Ursachen:

1. Insufficient or unset safety height (tool or chuck collides with the workpiece during rapid feed G00).
2. Mismatch between the tool listed on the program sheet and the actual tool used in the program.
3. Incorrect tool length (blade length) and actual machining depth listed on the program sheet.
4. Discrepancies between depth Z-axis values on the program sheet and actual Z-axis measurements.
5. Coordinate setting errors during programming.

Improvements:

1. Accurately measure the workpiece height and ensure the safety height is above the workpiece.
2. Ensure consistency between the tool listed on the program sheet and the actual tool used (preferably use automated or pictorial program sheets).
3. Measure the actual machining depth on the workpiece, clearly noting the tool length and blade length on the program sheet (typically, the tool clamping length should be 2-3mm above the workpiece, and the blade clearance should be 0.5-1.0mm).
4. Accurately measure the Z-axis on the workpiece and clearly note it on the program sheet (this is usually a manual operation and should be double-checked).

CNC Crash – Operator Errors

Die Ursachen:

1. Incorrect Z-axis depth tool setting.
2. Errors in centering and operation numbers (e.g., not accounting for tool radius in single-side measurements).
3. Using the wrong tool (e.g., using a D10 tool instead of a D4).
4. Running the wrong program (e.g., running A9.NC instead of A7.NC).
5. Incorrect manual operation of the handwheel direction.
6. Pressing the wrong direction during manual rapid feed (e.g., pressing X instead of -X).

Improvements:

1. Pay attention to the tool setting position on the Z-axis (bottom surface, top surface, split surface, etc.).
2. Double-check centering and operation numbers after completion.
3. Repeatedly check the tool against the program sheet and program before clamping.
4. Run programs sequentially and in order.
5. Operators should improve their proficiency with manual machine operations.
6. Raise the Z-axis above the workpiece before moving it manually and quickly.

Surface Accuracy in Curved Areas

Die Ursachen:

1. Unreasonable cutting parameters leading to rough surfaces on curved workpieces.
2. Dull tool edges.
3. Excessively long tool clamping and blade clearance.
4. Poor chip removal, air blowing, and oil flushing.
5. Programming of the cutting path (consider using climb milling where possible).
6. Burrs on the workpiece.

Improvements:

1. Set reasonable cutting parameters, tolerances, allowances, and feed speeds.
2. Operators should regularly inspect and replace tools as needed.
3. Clamp tools as short as possible, minimizing blade clearance.
4. Set appropriate cutting, feed speeds, and tool types (flat, R, and ball nose cutters).
5. Workpiece burrs are directly related to the machine, tool, and cutting path. Understanding the machine’s capabilities is crucial for re-cutting burr edges.

The post How Top CNC Machining Factories Handle CNC Machining Defects appeared first on Prototool written by Prototool.

Die casting molds are one of the four essential elements in die casting production (alongside casting materials, equipment, and processes). Cracking in the die casting mold cavity is a common and severe failure mode, directly impacting production scheduling. The primary causes of mold cavity cracking include direct contact with high-temperature metal liquids, erosion during the filling stage by high-speed flowing metal, and the impact of high pressure during the pressurization stage. Additionally, the severe fluctuation of mold steel temperature in each casting cycle contributes to this issue.

A proficient die casting company embraces the challenges in various processes. Addressing and resolving different process issues enriches manufacturing experience, enabling the production of satisfactory parts for diverse clients.

Factors Related to Die Casting Mold Cracking

1.1 Mold Design

1.1.1 Material Selection

For the forming parts of die casting molds, specific hot work mold steels are commonly chosen. Grades like 1.2343 and 1.2344 are suitable for large molds, while 1.2367 is preferred for parts where erosion is severe. However, due to processing difficulty and hardenability issues, 1.2367 is not ideal for very large forming parts. It’s recommended to use high-grade varieties processed with electroslag remelting technology, as they have lower impurity content and less variation between core and surface, reducing the risk of cracking.

Model	High-Temperature Strength	High-temperature toughness	High-temperature wear resistance	Machinability
1.2343/8402/H11/SKD6
1.2344/8407/H13/SKD61
1.2367/8418

1.1.2 Product Geometric Shape

Common risks include:

• a. Deep groove structures with small draft angles or excessive length-to-diameter ratios;
• b. Insufficient local radii causing stress concentration;
• c. Inadequate draft angles in areas eroded by molten aluminum;

All of these common risks need to be improved from a product design perspective, as follows

1.1.3 Mold Geometric Shape

Common risks include:

• a. Insufficient local radii leading to stress concentration;
• b. Sharp angles and knife edges caused by insert structures;
• c. Weak structures in mold filling channels;

All of these common risks need to be avoided from a parting design perspective.

1.1.4 Gating System Design

Common risks include:

• a. Insufficient radii in gate design;
• b. Gates facing weak structural areas;

These common risks need to be avoided from the gating system design point of view, see the following figure:

1.1.5 Cooling System Design

Common risks include:

• a. Excessively deep cooling holes leading to insufficient local strength;
• b. Poor cooling layout causing significant temperature distribution differences and stress;

These common risks need to be balanced from a cooling system design perspective, as below:

1.2 Mold Manufacturing

1.2.1 Material Control

As per the North American Die Casting Association (NADCA) standards, high-quality materials from mainstream suppliers typically meet or exceed these standards, reducing the likelihood of defects.

1.2.2 Machining Methods

Electrical Discharge Machining (EDM) can affect the surface composition and structure of the mold, leading to micro-cracks and stress concentration. Minimizing the use of EDM can significantly reduce the risk of mold cracking.

1.2.3 Machining Parameters

Adhering to the recommended machining parameters for the selected material, such as cutting speed, feed per revolution, cutting depth, and tool type, is essential. Deviating from these guidelines can result in residual stress and potential stress cracks.

1.2.4 Stress Relief Grinding

EDM is often unavoidable in large die casting mold processing. Post-EDM, it’s crucial to grind and polish the affected areas as per the material guidelines to remove harmful structures and alleviate stress.

1.2.5 Heat Treatment Process

The heat treatment of mold materials includes softening, stress relieving, and hardening. Following the detailed requirements for quenching media, cooling rate, and tempering intervals in the material guidelines ensures the internal and external structure of the material meets expectations.

1.2.6 Nitriding Control

Nitriding enhances the mold’s surface wear resistance, delaying the erosion caused by molten aluminum. However, it also makes the surface more brittle and increases the risk of cracking. The depth and conditions of nitriding must be strictly controlled, especially for large parts (0.03-0.07 depth).

Process Design and Its Impact

1.3.1 Hot Mold Process

The method of starting production with a cold mold greatly affects the life of the mold, especially due to thermal stress caused by alternating cold and hot impacts. It’s recommended to preheat the mold using a mold temperature machine rather than starting directly with a low-pressure hot mold. During a cold mold start, typically 5-10 low-pressure, low-speed injection cycles are needed to raise the mold temperature. Therefore, it’s crucial to avoid initiating high-speed, high-pressure injection cycles too early.

1.3.2 Cooling Techniques

The chosen cooling process in production significantly impacts the thermal stress on the mold surface. This is evident in the maximum and minimum temperature differences during the die casting cycle and on the mold surface. The former often leads to cracking and crack development, while the latter can cause stress cracks.

A good cooling process should consider controlling the cooling water time, cooling during the solidification stage, and avoiding constant cooling throughout the cycle. It’s also important to control the temperature drop from spraying and rely less on spraying for cooling. Ensuring a compact cycle time is crucial to avoid large fluctuations in mold temperature differences within the cycle.

1.3.3 Injection Speed

Erosion from molten aluminum significantly damages the mold. A lower gate speed is more beneficial for mold life. To balance filling quality, it’s advised to keep the gate filling speed within 30-50m/s. If possible, try to control the filling speed of each branch gate below 45m/s.

1.3.4 Boost Pressure

Reducing casting pressure is beneficial for extending mold life. The recommended injection pressure should be below 100MPa. Choosing the right timing for boosting pressure is also crucial for mold longevity, so avoid boosting too early or too late.

Maintenance and Care for Prolonging Mold Life

1.4.1 Production Scheduling Habits

Production scheduling habits significantly affect mold life, mainly due to temperature fluctuations caused by intermittent production. Continuous 24-hour production leads to a dynamic equilibrium in mold temperature, reducing the temperature difference in each cycle and across different mold areas. Intermittent production, leading to frequent cold mold startups, increases thermal stress, causing cracks and crazing, negatively impacting mold life.

1.4.2 Mold Spot Checks

Timely removal of aluminum adhesion on the mold surface can reduce demolding resistance and delay crack development. For areas severely eroded by molten aluminum, electro-discharge coating is recommended to enhance local wear resistance and delay the onset and development of crazing.

1.4.3 Mold Maintenance

Periodic stress-relief annealing can eliminate thermal stress to some extent. Cleaning the mold surface of aluminum adhesion and dirt reduces erosion. Regular checks for proper mold closing can prevent excessive squeezing and damage during operation.

Conclusion and Preventative Measures

To prevent die casting mold cracking, it’s essential to:

1. Minimize occurrences of sharp angles, insufficient fillets, and inadequate draft angles in mold design. Collaborate with product design early to mitigate risks.
2. Be cautious in selecting steel materials with poor through-hardening properties for large molded parts. Avoid excessively high hardness and deep nitriding layers to prevent significant hardness differences within the workpiece.
3. Opt for lower gate speeds, reduced boost pressures, and appropriate boosting timing in the process design. Shorten the die casting cycle to minimize temperature variations.
4. Reduce downtime and strictly control the cold mold startup process. Preheating molds with a mold temperature machine can help stabilize temperature fluctuations during startup.

The post Analysis of Cracking Factors in Large Die Casting Molds appeared first on Prototool written by Prototool.

Druckguss ist eine herausragende Metallgusstechnik, die durch die Anwendung von hohem Druck auf geschmolzenes Metall in einer Form gekennzeichnet ist. Formhohlraumund zieht Parallelen zum injeSpritzgießen von Kunststoffen. Dieses Verfahren eignet sich besonders für die Herstellung einer großen Anzahl kleiner bis mittelgroßer Gussteile und ist damit das am weitesten verbreitete unter den verschiedenen Gießverfahren. Im Vergleich zu anderen Gießverfahren bietet das Druckgießen eine glattere Oberfläche und hervorragende Maßhaltigkeit. Es ist jedoch wichtig zu wissen, dass unsachgemäße Verfahren und Parameter zu einer Vielzahl von Problemen führen können. Druckgussfehler.

Fließspuren und Muster beim Druckgießen

Wenn man die Oberfläche von Druckgussteilen untersucht, kann man Folgendes feststellen Schlieren die mit der Fließrichtung des geschmolzenen Metalls übereinstimmen. Diese Schlieren, die sich von der Farbe des Grundmetalls unterscheiden, weisen richtungsunabhängige Muster auf und zeigen keine Anzeichen für ein Fortschreiten.

Das Verständnis der Ursachen für diese Fließspuren ist unerlässlich, um solche Druckgussanomalien abzumildern. Hier sind einige der Hauptgründe für ihre Entstehung:

Hauptursachen für Fließspuren

1. Niedrig Temperatur der Form: Eine unzureichend beheizte Form kann zu einer vorzeitigen Erstarrung des geschmolzenen Metalls führen, was diese Schlieren zur Folge hat.
2. Schlechtes Angussdesign und unzureichende Angusspositionierung: Die Kanäle, die das geschmolzene Metall in die Form leiten, können, wenn sie nicht optimal gestaltet sind, den Fluss stören, was zu diesen Fehlern führt.
3. Niedrige Materialtemperatur: Wenn das geschmolzene Metall nicht heiß genug ist, fließt es möglicherweise nicht gleichmäßig und verursacht Unregelmäßigkeiten auf der Oberfläche.
4. Langsame Füllgeschwindigkeit und kurze Füllzeit: Ein langsamer oder ungleichmäßiger Guss kann zu ungleichmäßiger Abkühlung und Verfestigung führen, was sichtbare Fließspuren zur Folge hat.
5. Ineffizientes Gießsystem: Ein unsachgemäß konstruiertes System kann den reibungslosen Fluss des geschmolzenen Metalls behindern und diese Muster verursachen.
6. Unzureichende Entlüftung: Ohne ordnungsgemäße Entlüftung können Lufteinschlüsse den Fluss des geschmolzenen Metalls stören und zu Oberflächenfehlern führen.
7. Unsachgemäßes Sprühen: Ungleichmäßiges oder unsachgemäßes Sprühen kann die Temperatur und den Fluss des geschmolzenen Metalls beeinträchtigen, was zu diesen Fehlern führt.

Dendritische Rissbildung beim Druckgießen

Bei der Inspektion von Druckgussteilen kann man ein Netz oder baumartiges Muster von Rissen auf der Oberfläche. Diese dendritische Risse kann mit zunehmender Anzahl von Gießzyklen immer ausgeprägter und verbreiteter werden.

Das Verständnis der Ursachen für dendritische Risse ist für die Herstellung hochwertiger Druckgussteile unerlässlich. Hier sind die Hauptgründe für das Auftreten dieses Fehlers:

Hauptursachen der dendritischen Rissbildung

1. Risse auf der Oberfläche der Druckgießform: Selbst kleine Risse auf der Formoberfläche können zur Bildung von dendritischen Mustern auf dem Gussteil führen.
2. Ungleichmäßiges Vorwärmen der Druckgießform: Wenn eine Form nicht gleichmäßig erwärmt wird, kann das geschmolzene Metall ungleichmäßig erstarren, was zu dendritischen Rissen führt. Um solche Defekte bei Druckgussteilen zu vermeiden, ist ein gleichmäßiges und korrektes Vorheizen entscheidend.

Kaltverformungen beim Druckgießen

Kalte Fensterläden sind eine der häufigsten Unvollkommenheiten im Druckgussverfahren. Bei der Inspektion von Druckgussteilen können Sie deutliche, unregelmäßige und lineare Vertiefungen auf der Oberfläche feststellen. Diese Vertiefungen können entweder durchdringend oder nicht durchdringend sein. Sie sind in der Regel schmal und länglich, und manchmal erscheinen ihre angrenzenden Kanten glatt. Unter äußerer Einwirkung besteht die Möglichkeit, dass diese Bereiche brechen oder sich ablösen.

Das Verständnis der Ursachen von Kaltverschlüssen kann dazu beitragen, diese Anomalie im Druckguss zu mildern. Hier sind die Hauptgründe für das Auftreten dieses Fehlers:

Hauptursachen für Cold Shuts

1. Unvollständige Metallschmelze: Wenn zwei Ströme geschmolzenen Metalls zusammentreffen, aber nicht vollständig verschmelzen, und keine Verunreinigungen dazwischen liegen, kann die entstehende Verbindung schwach sein. Dieses Szenario führt häufig zur Bildung von Kaltverschlüssen.
2. Niedrige Gieß- oder Formtemperatur: Wenn die Temperatur des geschmolzenen Metalls oder der Druckgussform zu niedrig ist, können die Metallströme nicht richtig zusammenfließen, was zu Kaltverschlüssen führt.
3. Ungeeignete Position des Gates oder verlängerter Fließweg: Die Position des Anschnitts oder ein zu langer Fließweg können den reibungslosen Fluss des geschmolzenen Metalls behindern und die Gefahr von Kaltverschlüssen erhöhen.
4. Langsame Befüllungsgeschwindigkeit: Eine langsame Gießgeschwindigkeit kann dazu führen, dass das heiße Metall zu früh aushärtet und die Form nicht vollständig ausfüllt, was zu kalten Spalten oder Fehlern führen kann. Die Gewährleistung einer optimalen Füllgeschwindigkeit ist entscheidend, um solche Gussfehler zu vermeiden.

Schrumpfungsdefekte (Einfallstellen)

Visuelle Inspektion:

Wenn man die Oberfläche dickerer Abschnitte von Druckgussteilen untersucht, kann man glatte Vertiefungen erkennen, die der Form einer Untertasse ähneln.

Ursachen von Schrumpfungsfehlern:

1. Durch Kontraktion verursachte Probleme:

• Eine unsachgemäße Konstruktion des Druckgussteils führt zu erheblichen Dickenschwankungen.
• Falsche Positionierung der Angusssystem.

• Unzureichender Druck während des Gießvorgangs und kurze Haltezeit.
• Überhitzung in bestimmten Bereichen des Druckgießform.

2. Unzureichende Auslegung des Kühlsystems:

Die Konstruktion des Kühlsystems spielt eine entscheidende Rolle bei der Erstarrung des geschmolzenen Metalls. Eine ineffiziente Konstruktion kann zu einer ungleichmäßigen Abkühlung führen, was wiederum zu Schwindungsdefekte.

3. Vorzeitiges Öffnen der Form:

Ein zu frühes Öffnen der Form, bevor das Metall vollständig erstarrt ist, kann zu Einfallstellen auf der Oberfläche des Teils führen.

4. Überhöhte Gießtemperatur:

Eine zu hohe Temperatur des geschmolzenen Metalls kann das Problem der Schrumpfung verschlimmern. Es ist wichtig, eine optimale Temperatur einzuhalten, um eine gleichmäßige Erstarrung zu gewährleisten und Anomalien beim Gießen zu minimieren.

Empfehlungen zur Vermeidung von Schrumpfungsfehlern:

Um das Risiko von Schrumpfungsfehlern zu minimieren, ist es wichtig, sich auf die Konstruktionsphase zu konzentrieren. Die Sicherstellung einer gleichmäßigen Wandstärke, die Optimierung des Anschnittsystems und die Einhaltung der richtigen Gießparameter können einen großen Beitrag zur Herstellung hochwertiger Druckgussteile leisten. Die regelmäßige Überwachung und Anpassung der Prozessvariablen in Verbindung mit einer routinemäßigen Wartung der Form kann die Gussqualität weiter verbessern und das Auftreten solcher Fehler verringern.

Die Markierungen

Visuelle Inspektion:

Auf der Oberfläche der Gussteile sind Spuren des Kontakts mit dem Druckgussformhohlraum oder stufenförmige Abdrücke auf der Oberfläche der Gussteile zu sehen.

Ursachen von Stempelabdrücken:

Schleudertrauma-bedingte Ursachen

1. Verschleiß an der Stirnseite der Auswerferstift.
2. Inkonsistente Einstelllängen der Auswerferstifte.
3. Schlechte Ausrichtung zwischen den Teilen des Druckgussformhohlraums.

Ursachen im Zusammenhang mit der Montage oder dem Transport von Teilen

1. Lösen der eingesetzten Teile.
2. Verschleiß oder Lockerung von beweglichen Teilen.
3. Die Seitenfläche des Gussteils wird durch die ineinander greifenden Einsätze der beweglichen und festen Form gebildet.

Lötstellen beim Druckgießen

Visuelle Inspektion:

Bei der Untersuchung kann man kleine Flecken auf der Druckgussoberfläche beobachten, wo das Gussmetall unbeabsichtigt mit der Form verschmolzen ist. Diese Flecken, die entweder metallisch oder nichtmetallisch sein können, können sich durch äußere Kräfte ablösen. Sobald sie sich ablösen, können die betroffenen Stellen auf der Gussoberfläche entweder glänzend oder dunkelgrau erscheinen.

Ursachen von Lötflecken:

1. Vorhandensein von Reststoffen: Die Oberfläche des Formhohlraums kann Reste von metallischen oder nichtmetallischen Substanzen aufweisen.
2. Beim Gießen eingebrachte Verunreinigungen: Während des Gießens können Verunreinigungen eingebracht werden und an der Formoberfläche haften bleiben.

Kaschierungsdefekte

Visuelle oder zerstörende Inspektion:

Bei der Inspektion zeigen sich in bestimmten Bereichen des Druckgussteils deutliche Metallschichten.

Ursachen von Laminierungsfehlern:

1. Unzureichende Steifigkeit der Form: Während des Metallfüllvorgangs kann die Form vibrieren, wenn sie nicht die nötige Steifigkeit aufweist.
2. Probleme mit der Stößelbewegung: Unregelmäßigkeiten oder Kriechvorgänge in der Bewegung des Stempels während der Schussphase können zu diesen Fehlern führen.
3. Unsachgemäßer Aufbau des Gattersystems: Die Gestaltung des Anschnittsystems spielt eine entscheidende Rolle bei der Gewährleistung eines fehlerfreien Gusses. Eine ungeeignete Konstruktion kann zu flächigen Fehlern führen.

Metallerosion beim Druckgießen

Visuelle Inspektion:

Bei der Untersuchung weisen bestimmte Bereiche der Oberfläche des Druckgussteils eine auffallend raue Struktur auf.

Ursachen für Metallerosion:

1. Probleme mit dem Gating System: Die unsachgemäße Positionierung, Richtung und Form des internen Anschnittsystems in der Druckgussform kann zu einem turbulenten Fluss des geschmolzenen Metalls führen, was die Gefahr der Erosion erhöht.
2. Unzureichende Kühlung: Werden die turbulenten Bereiche der Metallschmelze innerhalb des Anschnittsystems gießbedingt nicht ausreichend gekühlt, kann dies den Erosionseffekt an der Oberfläche der Form verstärken.

Rissbildung in Druckgussteilen

Visuelle Inspektion:

Wenn das Druckgussteil in eine alkalische Lösung getaucht wird, erscheinen die Bereiche mit Rissen in einem dunkelgrauen Farbton. Die Beschädigung der Metallmatrix und die Öffnung der Risse können linear oder wellenförmig sein. Diese Risse sind schmal und langgestreckt und neigen dazu, sich auszubreiten oder zu wachsen, wenn sie äußeren Kräften ausgesetzt sind.

Ursachen der Rissbildung:

1. Probleme mit der Legierungszusammensetzung:

1. Zu hoher Eisengehalt oder zu geringer Siliziumgehalt in der Legierung.
2. Schädliche Verunreinigungen in der Legierung können bei hohen Werten die Duktilität der Legierung verringern.
3. Aluminium-Silizium-Legierungen oder Aluminium-Silizium-Kupfer-Legierungen mit hohem Zink- oder Kupfergehalt.
4. Aluminium-Magnesium-Legierungen mit einem zu hohen Magnesiumgehalt.

2. Fragen zum Gießverfahren:

2. Kurze Formhaltezeit und kurze Druckhaltezeit.
3. Teile des Gussstücks mit erheblichen Wanddickenschwankungen.

3. Ungleichgewicht der Kräfte:

3. Übermäßige örtlich begrenzte Klemmkraft, die zu ungleichmäßigen Kräften beim Auswerfen führt.

Navigieren durch die Komplexität des Druckgusses

Es gibt noch viele andere Arten von Druckgussfehlern, und wir werden in Zukunft Gelegenheit haben, jeden einzelnen von ihnen genau zu erklären. Wir bei Prototool sind stolz auf unser Fachwissen im Bereich der Druckgussdienstleistungen. Unser qualifiziertes Team kann verschiedene Fehler beheben, um sicherzustellen, dass das Endprodukt in Bezug auf Qualität und Haltbarkeit erstklassig ist. Wir sind bestrebt, exzellent zu sein und immer besser zu werden, was Prototool zu einem zuverlässigen Partner für Ihre Druckgussanforderungen macht. Vertrauen Sie uns, wenn es darum geht, die Komplexität dieses Prozesses zu bewältigen und jedes Mal hervorragende Ergebnisse zu liefern.

The post Common Die Casting Defects: A Brief Overview of Causes and Solutions appeared first on Prototool written by Prototool.

Warpage, the Spritzgießer‘ nemesis! It’s a common problem, especially during the fine-tuning process. Now picture a part that should match the Hohlraum but decides to deviate, resulting in a warped section. In this scenario, even non-experts can spot the bending or twisting.

So what do you do in this situation? Simple: avoid unintentional bending to prevent warpage in plastic products from occurring in the first place on the plastic part.

However, if you still encounter the same issue, it’s crucial to identify the cause, types, and solutions of warpageto prevent it from impacting the overall quality of the Spritzgussteil.

Today, we’re going to demonstrate a detailed approach to understanding, detecting, and solving defects like warpage.

Lesen Sie auch: KI-unterstütztes Spritzgießen: Wie künstliche Intelligenz die Fertigung verändert

The Different Types of Warpage or Shrinkage:

So what exactly is a warping? Simply put, it’s only a product shape difference due to shrinking. In other words, it is a type of Schrumpfung that extends in all directions and consistently reduces product size while maintaining shape.

However, any change in the element’s orientations will cause internal stresses. If these stresses exceed the component’s structural integrity, a warp will emerge in the ejected component.

There are three forms of shrinking in plastic parts, including

Regional Shrinkage

The regions closest to the Tor and the regions closest to the end of the fill are the most likely to undergo regional shrinkage. When identifying this shrinkage, the difference between the thickest and thinnest areas in the affected region should be obvious.

If the plastic product is undergoing regional shrinking, you will find one area of the product contracting faster than the others.

Directional Shrinkage:

Even though shrinkage varies from molecule to molecule and fiber alignment to fiber alignment, it can also occur in the orientation of the materials. At most, shrinkage manifests itself in both amorphous and crystalline substances.

But in contrast to crystalline materials, which typically shrink perpendicular to the flow direction, amorphous materials tend to contract along the flow direction.

Shrinkage via Thickness

When there is shrinkage on the cross-section of the part, the top part of the shrinkage is notably different from the bottom part.

In this scenario, the shrinkage or warpage in plastic products will be caused by thickness. As a result, you will have to bend the component from the side and decrease it further.

Different Plastics and Their Shrinkage Rates:

Shrinkage Rates of Common Plastics

Shrinkage Rates of Engineering Plastics

How To Prevent Plastic Warpage?

When you manufacture plastic through the injection molding technique, you will see that plastic can twist because of mistakes in the mold, the choice of material, or the Spritzgießmaschine.

To prevent this, it is important that you or your chosen injection molding company pays attention to all of these mentioned mistakes and avoid them in the first place, keeping the plastic from getting soft.

Still unsure how to keep the plastic from getting soft? Try these methods:

• Differential shrinkage and orientation effects can be kept to a minimum if your maker wants to.
• One can also set the gates of the mold so that the flow goes in only one direction.
• You can change the mold’s width to ensure it is the same thickness all over.
• The manufacturer should try to make the mold so that extra material is only added to the thick parts of the walls to make the structure more stable. This should only be done if the mold can’t be made stronger in any other way.
• The manufacturer can also add things like stiffening ribs to the design if they want to. You can change how the part is made so that there are no thick parts and the thickness of any features that meet the main surface is less.
• It’s important to remember that semi-crystalline plastic resins naturally shrink more than crystalline plastic resins, making them more likely to bend. If you don’t need these materials for your part or product, you should try to stay away from them.

Problems That Lead to Warping in Injection Molding + The Solutions:

Problem#1: Insufficient Injecting Time or Pressure 

If there isn’t enough pressure on the filling, the plastic will cool and harden before the mold is filled properly.

The packing process is sped up if the plastic injection hold time isn’t long enough.

The molecules won’t be held together if there isn’t enough mold-filling pressure or hold time. This means they can move around uncontrollably as they cool. This makes the part cool down at different speeds, which causes the mold to twist.

Lösung:

Make the injection pressure or hold time for the cast higher.

Problem#2: Inadequate Residence Time

The amount of time the resin is heated in the Fass is called its “residence time.” If there isn’t enough time for the molecules to stay in one place, the heat won’t be absorbed evenly throughout the object.

If you don’t heat the material enough, it will get stiff and cool before the mold is packed properly. The molecules shrink at different rates during the cooling process, which makes the mold twist.

Lösung:

Add more time to the cooling part of the cycle to lengthen the time the water stays in one place. This will ensure the material stays in place for the right time and stop the mold from breaking.

Problem#3: Low Temperature in the Barrel

If the temperature of the barrel is too low, the resin can’t get hot enough to move.

Likewise, if the glue is not at the right temperature to flow and is pushed into the mold, it will harden before the molecules are packed correctly. This makes the molecules shrink at different rates, causing the mold to twist.

Lösung:

Raise the warmth of the barrel. Make sure that the temperature of the material melted is the same throughout the shot size.

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Problem#4: Low Temperature For Mold Growth

If the mold isn’t hot enough, the molecules will solidify before they pack together at different rates, which will cause the mold to twist.

Lösung:

Raise the temperature of the mold based on what the resin seller says to do and make adjustments as needed. For every 10-degree change, operators should give the process ten re-stabilization rounds.

Problem#5: Different Temperatures in the Mold

When the mold temperature isn’t even, the molecules cool and shrink at different rates. This makes the mold shift.

Lösung:

Look at the mold parts that touch the liquid resin. Use a pyrometer to determine if the temperature difference is more than 10 degrees F.

However, if the temperature difference between any two places is more than 10 degrees, even between the two halves of the mold, there will be a difference in how fast the parts shrink and the mold warp.

Problem#6: Low Temperature of the Nozzle

Since the tip is the last connection between the barrel and the mold, it’s important to look at it. If the opening is too cold, the resin can move more slowly, making it hard for the molecules to pack together correctly. The molecules won’t shrink simultaneously if they don’t fit together properly. This makes the mold warp.

Lösung:

To solve this problem, make sure that the design of the nozzle isn’t affecting the flow rate.

Now, some nozzles aren’t made for the resin being used. If the correct nozzle for the flow and resin is being utilized and the mold is still warping, you should adjust the nozzle temperature by 10 degrees Fahrenheit until the warping issue is resolved.

Problem#7: Not Enough Flow

Resin manufacturers make different mixes for standard flow rates. Using these standard flow rates as a guide, you should choose a material that is easy to flow for products with thin walls and a stiffer material with thick walls.

For thin or thick-walled products, the operator should use the stiffest material possible since a stiffer flow improves the mold’s physical qualities. But the harder it is to push something, the stronger it is.

However, if it’s hard to push the material, it might harden before it can be packed. This causes molecules to shrink at different rates, which makes the mold shift.

Lösung:

Manufacturers should work with the resin seller to determine which material will have the stiffest flow rate without causing warping.

Problem#8: Improper Processing Cycle

If the operator opens the gate too soon and the product comes out before the material has had enough time to cool down evenly, the operator has cut the process cycle short. A process cycle that isn’t always the same can cause shrinking rates that can’t be controlled, which can cause the mold to warp.

Lösung:

Manufacturers should use a process loop that runs itself and only step in if there is an emergency. Most importantly, all workers should be told how important it is to keep process cycles consistent.

Problem#9: Inadequate Gate Size

When the gate size isn’t right, it slows down how fast the hot resin can flow through. If the size of the gate is too small, the rate at which the plastic fills can slow down enough to cause a huge loss of pressure from the point of the gate to the last point to fill.

This can cause the molecules to be physically stressed. When this stress is removed after injection, mold warp happens.

Lösung:

The data from the resin source should be used to find the best size and shape for the mold gate. Most of the time, the best way to fix mold warpage in plastic products is to make the gate as big as possible.

Problem#10: Wrong Gate Position

In addition to the size of the gate, the position of the gate can also cause a mold to warp.

If the gate location is in a thin area of the part shape and the last point-to-fill is in a much thicker area, the filling rate can change from thin to thick. This may result in a substantial pressure drop. Eventually, this huge pressure loss can lead to a short or insufficient fill.

Lösung:

The gate may need to be moved, so the mold must be redesigned. This is so that the mechanical properties of the end product can be met.

Sometimes, more gates need to be added to reduce air loss and reduce the amount of stress that is built into the mold.

Problem#11: Irregular Ejections

If the mold’s ejection system and press aren’t regularly checked and changed, they might not work right and cause uneven ejection force or parts that aren’t straight. These problems can cause stress in the mold as it tries to keep the part from coming out. After the part has been ejected and cooled, the forces cause the mold to warp.

Lösung:

Operators should ensure the release system and press are checked and adjusted regularly. All adjusting tools should be locked to keep parts from moving and ensure they are well-oiled.

Problem#12: Improper Product Geometry

The product’s shape can also cause mold warping. The shape of a part can lead to many different filling patterns, which can cause the plastic to shrink differently in different parts of the hollow. If the design makes the rate of shrinkage uneven, warping can happen.

This is especially true if there is a lot of pressure loss in places where the wall stock is thin and not thick.

Lösung:

In this regard, consulting professional plastic injection molding service providers like Prototool can help you address and solve the issue in time.

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Wrap-Up:

Warping in injection molding or warpage in plastic products can be a huge concern when manufacturing plastic products. It does not affect the appearance of a product or part but also impacts the quality and performance of the part.

With this detailed guide, you can thoroughly understand how to detect and solve plastic part warping issues.

The post The Causes and Solutions of Warping in Injection Molding appeared first on Prototool written by Prototool.

Although the plastics manufacturing business has been more productive thanks to plastic injection molding service, its finished products don’t always meet the client’s expectations. From lack of efficiency in managing the injection molding process to operating errors, production errors, and whatnot – different aspects of this production approach can lead to common injection molding defects. Air bubbles or vacuum voids are one such common injection molding defect that is often overlooked. While they may seem minor, facing vacuum voids in injection molding can make a product inefficient and low quality.

Now if you’re wary of this issue and don’t want to make it affect your production quality and consistency in any way, let’s dive deeper into the causes of vacuum voids in injection molding.

This article will closely explore how you can get rid of this common defect, maintaining the quality of the final product.

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Identifying Vacuum Voids in Injection Molding:

Vacuum voids, also known as air pockets, are pockets of air that remain after a plastic part has been molded. Larger or more numerous voids can weaken the molded item.

However, this is often considered a “minor” flaw that does not necessarily jeopardize the product’s functionality. You can see an example of a vacuum void occurrence in a heated product:

Shrinkage in the interior of a plastic item commonly results in vacuum voids. In pieces made of see-through plastic, they are readily apparent. Opaque plastic components do not readily show them, but one can locate them through sectioning or CT scanning.

Injection-molded items with thick walls frequently have problems, such as vacuum spaces. Locations, where many channels converge to form a rib or wall are common places to find them in molds. These regions are particularly vulnerable to irregular cooling and shrinkage in the mold.

Is It a Bubble or a Void?

When addressing common injection molding defects, it can often be confusing to differentiate between bubbles and a void.

Precisely, bubbles result from gas forming in the melt stream under pressure. In contrast, the phenomenon known as “voids” refers to occurrences of plastic shrinkage that result in a space within the plastic wall stock.

Applying gradual heat to the region with a torch or heat gun will help you establish whether the features you observe are bubbles or voids. The wall stock will fall and reveal a sink if a void exists.

On the other hand, if it is a bubble, the wall stock will inflate because the gas contained within will expand.

Vacuum Voids & Gas Pockets: Are They Different?

Yes, they are both different. While air bubbles or vacuum voids in injection molding may seem similar to gas pockets, they are two different defects, both common in injection molded products.

But how do you know your issue before opting for a solution? Simply put, there is a clear distinction between the two, which can be determined with the help of a straightforward heat test, even though both problems are fundamentally associated with airflow.

If you warm the plastic component responsible for the bubble’s formation, it will either deflate or swell. If the bubble grows larger, the resulting space is a gas pocket; if the bubble shrinks, the resulting space is a vacuum void.

Because jetting is a front flow issue, gas pockets can appear in the completed item as a result of the process.

Causes of Vacuum Voids in Injection Molding:

During the cooling process, vacuum voids in injection molding can form anywhere in part —inside or outside the mold—but it most commonly occurs in the thicker regions.

Typically, when a part is thick, the core cools more slowly, which causes the polymer to shrink more, which in turn causes it to pull away from itself, creating a bubble.

So, when you’re increasing the temperature of the mold, it may cause the bubble to vanish but may result in the formation of a sink. This is evidence that the bubble in question was void.

Having said that, internal stresses, such as voids, are warning indicators that the part may not operate as planned. So it is important to address these voids before finalizing a part. 

At most, the cause of vacuum voids is insufficient plastic, so it is recommended that additional material be packed into the hollow.

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Troubleshooting Vacuum Voids:

Unsure how to prevent vacuum vents in injection molding? To prevent this issue, consider modifying the injection molding method once you have determined the root cause of the vacuum void.

For instance, you can make alterations or troubleshoot this issue by working on the mold’s design, injection pressure, cooling rate, runner size, gate size, or other parameters.

Either way, it is important to identify the cause first before finalizing what troubleshooting approach you will proceed with further. Now, let’s go ahead and explore the most effective troubleshooting options for vacuum vents:

● Fix the Mold Design:

In most cases, vacuum voids result from thick wall portions. It is important to keep in mind that the steel of the mold will be cooler than the molten plastic material, which will form a void.

Because the outside of the mold will cool more quickly than the inside, it is necessary to consider the holding pressure and time for the molten plastic to align itself properly with the mold’s walls.

In most cases, vacuum gaps are typically brought on by walls that are either nonuniform or excessively thick, and one of the most effective methods for removing vacuum voids is to rebuild the plastic part so that there are no thick parts.

So incorporating a higher mold temperature that enables all surfaces to cool at a more consistent rate is yet another method. We can use this method.

You can also repair the vacuum spaces by expanding the size of the gate or relocating the gate to a piece of the part that is already thicker. This prevents the material from prematurely cooling in the most susceptible to voids.

A larger Tor that requires more time to solidify will not only permit more molten material to flow into the Hohlraum, but will also compensate for the shrinkage caused by the mold.

In addition, the manufacturer might also consider expanding the size of the cold runners. However, this should be determined by the material being utilized in the production of the plastic component.

● Alter the Parameters Involved in Injection Molding Process:

Researchers have determined that thick or nonuniform walls are more likely to be the cause of forming vacuum voids. This finding clearly indicates that maintaining a consistent wall thickness is necessary to prevent vacuum spaces. Yet, avoiding using walls with a greater thickness is not always possible.

When molding thicker pieces than 6 millimeters, it is more difficult to prevent the formation of vacuum voids.

When the outer layer of the part cools at a higher rate than the inner layer, vacuum voids are created because the inner layer is forced to pull apart.

This ultimately results in the production of vacuum voids. When such a situation arises, the processing settings will usually exert the most significant influence in minimizing voids.

To correct the vacuum voids, you can make adjustments to the following process parameters in any combination that works for you:

• Boosting the shot size, the screw forward time, the hold pressure, the injection pressure, and the mold temperature, respectively.
• lowering the temperature of the melt lowering the speed of the injection process

It is also worth noting that while you inject the material into the molds, an insufficient amount of injection pressure is typically one of the primary contributors to the formation of vacuum voids. This pressure causes the material in the outermost layer, which is the one that is nearest to the wall, to cool more quickly.

Eventually, this quick cooling causes air bubbles to become trapped and leaves vacuum spaces within the substance of the product. Therefore, injecting the molten plastic at high pressure is necessary to forestall the creation of vacuum voids.

Additionally, this process eliminates air bubbles by packing additional material into the mold in a concentrated manner.

● Finalize the Materials Wisely:

It is vital to keep a close eye on the materials and their additives since they can also contribute to the production of voids. While the design of the mold and the process parameters may be the primary sources of voids, it is important to keep an eye on both factors. 

You should select materials that have a viscosity that is as low as possible, if at all possible. The resistance to flow is what we mean when we talk about viscosity.

Speaking of which, the bubbles that form in liquids with a lower viscosity tend to become flatter due to the effects of inertia. As a result, this reduces the likelihood that molten plastic will contain air bubbles.

Materials with a low viscosity can be described as having a thin and rapid flow, while materials with a high viscosity can be described as having a thick and slow flow. Styrene, for instance, has a higher viscosity than nylon, which means that nylon flows more smoothly and quickly than styrene.

You should be aware that another factor that plays a significant part in determining the viscosity is the temperature. Increasing the temperature will cause the material’s viscosity to decrease, which will, in turn, result in an increase in the flow rate.

However, temperatures that are too high not only lengthen the total cycle time but also harm the materials. Therefore, higher temperatures can cause the breakdown of materials and the generation of more gas.

You should also cool the molten material in a regulated manner to help avoid the formation of vacuum voids.

Lastly, it is crucial to thoroughly dry the material and eliminate any traces of moisture. This reduces the amount of off-gassing that could occur due to moisture, which could contribute to voids.

Zusammenfassung:

Vacuum gaps in molded parts can reduce manufacturing efficiency for many reasons. Therefore, it is important to ensure that the part you are producing does not consist of any common injection molded defect mentioned above.

The best way to do that is by understanding the causes of common injection molding defects like vacuum voids and seeking the assistance of a professional manufacturer like Prototool to ensure that the part you produce and launch in the market is defect-free.

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The post Vacuum Voids in Injection Molding: Unraveling The Most Common Injection Molding Defect appeared first on Prototool written by Prototool.

Jetting occurs in a molded component when molten material is injected into the Formhohlraum and starts solidifying before it fills the cavity. It is a type of distortion caused by this premature solidification.

Furthermore, jetting is frequently visible as a squiggly line on the surface of the final component, typically leading from the original injection gate. When an injection molded part has jetting defect, it will automatically become weaker due to the defect’s flow pattern.

If you’re looking for a way to identify this common plastic injection molding defect and solve it in time, this guide will take you through the defect, its identification, and troubleshooting methods. So keep reading to learn all about jetting in injection molding and how you can keep it from affecting the quality of your final product.

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Causes or Affects Jetting in a Plastic Part:

When producing a plastic part, there can be many processes that, if not monitored and conducted properly, can lead to jetting in the plastic part. According to a simulation experiment of jetting in injection molding held using a finite volume method, here are some specific injection molding process considerations that often lead to or affect jetting in part:

• If the force of inertia is stronger than the force of viscosity at the melt front, jetting will happen. When the viscosity exceeds the inertial force, the jetting changes to buckling and then to the old sequence filling.
• Die location of the gate is the most important thing for jetting. Jetting can happen when the gate faces straight into the cavity and is far enough away from the mold wall.
• The injection speed has a big effect on jetting and bending. When the injection speed is high, the length of the jet and how often it swings are both longer.
• In the processing temperature range, the melt temperature doesn’t have much of an effect on the length of the jet, but a high melt temperature makes the jet move less often and makes the buckling diameter bigger.

Identifying Jetting in a Plastic Part:

Identifying jetting in an injection molded part involves a systematic approach to observing and analyzing the molded parts.

Jetting in injection molding occurs when a high-velocity stream of molten plastic shoots out from the mold during the injection process, resulting in undesirable surface defects. Below is an image that shows how jetting in injection molded part looks like:

While it is an injection molding defect that can occur due to improper mold design and gate positioning, it is important to identify it in time and solve it before it impacts the overall quality of the plastic product.

Steps to identify jetting in injection molding

1. First, you should carefully examine the surface of the molded parts, looking for any obvious flaws or anomalies such as streaks, lines, or distortions. Pay attention to the spots where the plastic flow either changes direction or runs into impediments.

2. Pay particular attention to any components with sharp corners or edges, as this is where jetting is most likely to occur due to the quick change in flow direction in these places.

3. Now analyze the surface quality of the molded pieces in their entirety. It is important to keep an eye out for indicators of jetting, such as an uneven texture, roughness, or waviness in the material.

4. Take careful measurements of the key dimensions of the molded parts, paying particular attention to the places that are likely to jet. When comparing the dimensions that were measured to the specifications of the design, you can discover any discrepancies that were produced by jetting.

5. Examine the many process parameters of the injection molding procedure, such as the injection speed, the melt temperature, the mold temperature, and the cooling time. Evaluate the possibility that any of these elements, such as high injection speed or insufficient cooling time, could contribute to the formation of jets.

6. When inspecting the mold, you should look for potential problems that could lead to jetting. These problems include poor gate design, inadequate ventilation, worn-out or damaged mold surfaces, etc.

7. Now analyze the plastic substance that is being injected into the molds. While doing this analysis, pay attention to the melt flow rate, the viscosity, and the material’s compatibility with the surface of the mold. The likelihood of jetting can be increased by using materials that are incompatible with one another or by using a viscosity that is too high.

8. If you find jetting in injection molded parts, it’s important to perform troubleshooting to determine the underlying reason. You can modify the injection parameters, the temperature of the mold, or the gate placements to maximize the flow and reduce the impacts of jetting (explained descriptively below).

9. Another way to mimic the plastic flow within the mold cavity is by using software designed for injection molding simulation. This makes it easier to visualize any possible jetting issues and guides adjustments to the procedure.

10. Ultimately, recording the observations, analyses, and improvements performed to deal with jetting is important. This paperwork will act as a reference for any later production runs, and it will help prevent or minimize jetting in any molding procedures that follow.

By following these detailed steps and conducting a thorough analysis, it is possible to identify and address jetting in injection molding, ensuring the production of high-quality parts.

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Troubleshooting Jetting in Injection Molding:

Solution#1 Increasing the Gate Size

In injection molding, one way to fix a problem with the flow is to look at the size and shape of the gate. Start by figuring out if you can change the size of the gate.

Changing the gate size can help eliminate flow problems, depending on the shape and size of the product. If you can, choose a gate that is short and wide. This will help the molten plastic run in a more controlled and even way.

Also, consider using a fan-shaped or angled gate design, as these are very effective at reducing problems with jetting. Choosing the right size and shape for the gate makes it much less likely that jetting will happen during the injection molding process.

Solution#2: Changing the Gate Location

When injection casting, checking the location of the gate is another way to find and fix problems. Additionally, jetting occurs when the liquid resin is pushing out with force, and this problem worsens in locations with more open space.

However, you can stop jetting by ensuring that the plastic from the gate rapidly contacts a wall or surface inside the mold. So, consider checking to see if you can move the gate to a place where the resin can quickly hit a wall or surface.

Even if you can’t move the gate, you can get a similar effect by putting a needle or wall inside the mold hole to stop the resin flow. Jetting can be reduced or stopped by changing the flow direction and encouraging collisions inside the mold.

Solution#3: Reducing Injection Speed

Another solution to mitigate jetting in injection molding is to lower the injection speed settings, specifically through the gate. This can be accomplished using a multi-stage injection approach rather than reducing the overall injection speed.

 The likelihood of jetting can be significantly reduced by controlling the speed at which the molten plastic passes through the gate. Implementing a multi-stage injection process allows precise control over the flow rate during the critical stage when the plastic enters the mold cavity through the gate.

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Moreover, slowing down the injection speed, specifically at the gate, enables better regulation of the pressure and velocity of the molten plastic. This will minimize the occurrence of jetting and result in smoother, more consistent flow throughout the molding process.

Experimenting with different injection speed settings and employing a multi-stage injection technique provides an effective strategy to address and alleviate jetting issues in injection molding.

Solution#4: Reducing Resin Viscosity

Reducing the viscosity of the resin you use for plastic part production can also help troubleshoot jetting in part. Some effective ways to reduce the viscosity include:

Raise Resin Temperature: By increasing the temperature of the resin, you can lower its viscosity. This allows the resin to flow more easily during the injection process. Raising the resin temperature within the recommended operating range makes the molten plastic less prone to jetting.

Raise Mold Temperature: Elevating the mold temperature can also reduce resin viscosity. The increased heat in the mold helps to maintain the resin in a more fluid state, improving flowability and minimizing the chances of jetting occurring.

Changing to a High Fluidity Grade: For this, you can switch to a resin grade with higher fluidity or lower viscosity. Some resin grades are specifically designed to have better flow characteristics, ensuring smoother injection and reducing the likelihood of jetting defects.

Solution#5: Increasing the Holding Pressure

By increasing the holding pressure, you can make up for and maybe even hide the shooting problem. It is important to look at the choices for the holding pressure and make sure they are right for the injection molding application.

 If the holding pressure is too low, the molten plastic might not be kept inside the mold cavity well enough, which can cause jetting flaws. Adjusting the holding pressure to a higher level can help keep a better balance between the injection speed and hollow pressure, which can reduce jetting.

But it’s important to carefully adjust the holding pressure within the acceptable range to avoid problems like flashes or parts that don’t fit together right. Systematically increasing the holding pressure while monitoring the results can help you find the best setting to deal with jetting.

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Still have questions? Connect with our skilled manufacturers at Prototool.

The post Jetting in Injection Molding – Identifying the Cause and Troubleshooting the Defect appeared first on Prototool written by Prototool.

Injection molding discoloration is a variation from the plastic’s base color. Overheating, contamination, and faulty production could all contribute to this faulty component.

The degree to which a flaw in the part’s coloring due to thermal degradation is evident varies with the severity of the degradation. To avoid this problem, it’s important to have a firm grasp of the factors that can lead to injection molding discoloration during the plastic injection molding process. An example of a discolored product can be seen below.

Now, let’s go ahead and dive deeper into the analysis, impact, and solutions of discoloration in injection molded parts.

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Impact of Discoloration on Plastic Parts:

Die discoloration of plastic parts can have consequences for both the part’s appearance and function. Let’s study these consequences in more detail:

Product Aesthetics:

Plastic components that have been discolored can have a considerable adverse effect on the overall aesthetic appeal of the finished product. The appearance of the product being unpleasant, inconsistent, or even defective might be caused by streaks, stains, or an uneven distribution of color.

This can result in dissatisfied customers, an unfavorable view of the brand, and a loss of sales. Discoloration of plastic parts should be avoided at all costs, but this is especially true in industries like consumer electronics and automobiles, where appearance is paramount. This can lead to huge financial losses.

Product Performance:

Plastic components can also have their functional characteristics altered if they become discolored. The injection molding material may become weaker as a result of thermal degradation or chemical reactions that take place during the molding process. This results in a decrease in the material’s structural strength and mechanical strength. A good example of an impacted product due to injection molding discoloration.

A decrease in the coloration of a part can indicate a decrease in its resistance to impact, a decrease in its dimensional correctness, or a decrease in its resistance to chemicals. These functional flaws can potentially jeopardize the finished product’s performance and reliability, which may result in risks to users’ safety or the failure of the product itself.

Causes and Solutions of Discoloration in Injection Molded Parts:

Discoloration Due to Machining Issues:

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Discoloration Due to Mold Issues:

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Additional Causes of Discoloration:

Schlussfolgerung:

Knowing what causes injection molding discoloration will help ensure your parts are strong and immaculate.

If you work with the proper manufacturing business, you can be confident that they understand how to eliminate discoloration and other plastic injection flaws. Prototool takes pride in having a defect-free injection molding process.

The post Got Discoloration in Injection Molded Parts? Here’s How To Fit It! appeared first on Prototool written by Prototool.

Aufgrund seiner Präzision können während des gesamten Prozesses mehrere Probleme auftreten Spritzgießprozess. Die kosmetische oder strukturelle Integrität des Teils kann durch alles Mögliche beeinträchtigt werden, von Bedienerfehlern bis hin zu Mängeln in der Werkzeugkonstruktion. Ein häufiger Fehler, mit dem Hersteller während dieses Prozesses konfrontiert werden, sind fehlerhafte Fließlinien beim Spritzgießen.

Wenn Sie ein professioneller Hersteller sind, der während des Produktionsprozesses häufig mit Fließlinienproblemen konfrontiert wird, ist es an der Zeit, dass Sie lernen, wie Sie dieses Problem lösen oder verhindern können, dass es die Qualität und das Aussehen der produzierten Teile beeinträchtigt. In diesem Artikel erfahren Sie alles Wissenswerte über Fließlinienfehler beim Spritzgießen.

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Erkennen von Fließspuren:

Auf der Oberfläche eines Kunststoffgegenstandes haben Fließlinien meist die Form eines wellenförmigen Musters. Fließlinien können aber auch eine Vielzahl anderer Muster annehmen. Sie heben sich fast immer farblich vom Rest des Bauteils ab und sind eher dort zu sehen, wo der Gegenstand besonders schmal ist.

Spritzgießfließlinien fallen in der Regel in eine der in der folgenden Tabelle genannten Kategorien:

Was ist die Ursache für den Fließlinienfehler beim Spritzgießen?

Die Ursachen von Fließlinien lassen sich in vier Hauptkategorien einteilen. In jeder dieser Kategorien gibt es eine Vielzahl von Problemen, die die Produktion des Produkts beeinträchtigen und zu folgenden Problemen führen können Mängel. Beginnen wir damit, die verschiedenen Verfahren des Spritzgießprozesses zu untersuchen. Wir werden uns auch mit den spezifischen Fehlern befassen, die während dieser Verfahren auftreten können und zu Fließlinien führen.

Fehler im Spritzgießprozess:

Fehler im Spritzgießprozess können zu verschiedenen Problemen führen, insbesondere zu Fließlinienfehlern. Einige spezifische Fehler, die während des Spritzgießprozesses zu Fließlinien am Produkt führen können, sind:

• Ein unzureichender Nachdruck oder Einspritzdruck führt zu einer unzureichenden Anpressung der erstarrten Schmelze an die Werkzeugoberfläche. Dadurch kann es zu Fließlinienfehlern im spritzgegossenen Produkt kommen, die mit der Fließrichtung der Schmelze übereinstimmen.
• Wenn die Zyklusdauer zu kurz ist, wird die Schmelze möglicherweise nicht ausreichend erwärmt, während sie sich im Zylinder befindet. Wenn die Temperatur, bei der das Material schmilzt, zu niedrig ist, ist es unmöglich, das Material zu verdichten, während es unter Druck gehalten wird, was zu Fließlinien führt. Dieses Problem ist häufig mit einer unzureichenden Verweilzeit verbunden, die ebenfalls dazu führt, dass die Schmelze nicht lange genug im Zylinder verbleibt.
• Die niedrige Temperatur im Zylinder ist ebenfalls eine Überlegung wert, da sie zu einer niedrigen Temperatur in der Schmelze führen kann. Diese Temperaturen wirken sich auf den Halte- und Einspritzdruck aus, da dieser nicht hoch genug ist, um Schichten erstarrter Schmelze an der Oberfläche des Werkzeugs zu halten.
• Und schließlich, innerhalb der FassDie Düse ist der Ort, an dem sich die letzte Heizzone befindet. Sie überträgt die Wärme auf die geschmolzene Substanz. Wird die Düse nicht ausreichend beheizt, sinkt die Schmelzetemperatur, was zu den bereits erwähnten Druckproblemen führt.

Fehler in der Form:

Unbestreitbar ist die Formgestaltung ein wesentlicher Bestandteil des Spritzgießprozesses. Einige spezifische problematische Szenarien bei der Verwendung der Form können zum Auftreten von Fließlinien im Endprodukt führen. Zu diesen Problemen/Szenarien gehören:

• Die Vergrößerung einer Läufer, Tor, oder Anguss über das erforderliche Maß hinaus zu einem erhöhten Fließwiderstand führt. In Verbindung mit einem niedrigen Einspritzdruck führt dieses Problem zu einer Verringerung der Schmelzgeschwindigkeiten und kann zur Bildung von Fließlinien führen.
• Wenn die Schmelze in eine Form mit einer niedrigeren Temperatur eingespritzt wird, sinkt die Materialtemperatur schneller. Wenn geschmolzenes Material mit einer höheren Temperatur auf Material gegossen wird, das bei einer niedrigeren Temperatur erstarrt ist, führt das Temperaturgefälle zur Bildung von Fließlinien.
• Wenn die Form nicht richtig evakuiert wird, besteht die Gefahr von Verstopfungen. Die Schmelzefront kann die Feststoffschicht nicht gegen die Form drücken, was zur Bildung von Fließlinien führt.

Fließlinien aufgrund von Defekten im Material:

Fließlinien beim Spritzgießen können auch durch die Verwendung von fehlerhaftem Material verursacht werden. Wenn ein Formhohlraum ein signifikantes Fließlängen-zu-Dicke-Verhältnis aufweist, sollte das Material eine ausreichend niedrige Viskosität haben, um einen kontinuierlichen Fluss zu ermöglichen.

Dies kann durch eine Verringerung der Viskosität des Stoffes erreicht werden. Andernfalls führt die mangelnde Fließfähigkeit des Materials zu einem langsamen Fließen der Schmelze, was die zuvor beschriebenen Probleme mit der Kühlung und dem Druck verursacht.

In diesem Fall kann die Bildung von Fließlinien darauf zurückzuführen sein, dass der Schmierstoffgehalt des Materials nicht entsprechend dem Verhältnis von Fließlänge zu Wanddicke erhöht wurde. Je höher dieses Verhältnis wird, desto höher muss der Mindestschmierstoffgehalt sein.

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Fehler bei der Bedienung einer Spritzgießmaschine:

Auch Bedienerfehler können dazu führen, dass Fließlinien in einem Teil auftreten. Wenn der Bediener der Spritzgießmaschine beispielsweise den Prozess des Umdrehens der Tür falsch einschätzt, führt dies zu einem unregelmäßigen Wärmeverlust, den die Maschine dann versuchen muss, auszugleichen.

Da die Temperatur nicht gleichmäßig verteilt ist, entstehen kalte Stellen in der Form, die zur Bildung von Fließlinien führen.

Gegenmaßnahmen für Fließliniendefekte beim Spritzgießen:

Schlangenlinien:

Lösung#1:

Stellen Sie die Größe des Formangusses auf der Grundlage der Kavitätstiefe im Verhältnis zur Anschnitttiefe ein.

Infolgedessen vermischt die Strahlaufweitung die Schmelze hinter dem Anschnitt mit der Vorderkante und verdeckt so ihre Wirkung.

Dies geschieht, wenn die Anschnitttiefe etwas geringer ist als die Kavitätstiefe. Wenn die Anschnitttiefe der Kavitätstiefe entspricht oder nahe daran liegt, ist die Formfüllrate gering, was zu einem Streufluss führt.

Lösung#2:

Nehmen Sie die erforderlichen Anpassungen am Winkel des Formangusses vor. Der Winkel zwischen dem Formschieber und der beweglichen Form beträgt 45 Grad.

Dies bedeutet, dass die Schmelze, wenn sie aus dem Anschnitt fließt, zuerst von der Formhohlraumwand aufgehalten wird, was eine Schlangenbewegung verhindert. Der Winkel zwischen dem Anschnitt und der sich bewegenden Form beträgt 45 Grad.

Lösung#3:

Bringen Sie die Formtüren in eine günstigere Position. Da der Anguss rechtwinklig zur Wand des Formhohlraums angeordnet ist (rechtwinklig zur Richtung des Angusses), hält die Wand des Formhohlraums die Schmelze zunächst vom Anguss ab.

Dies verhindert das Entstehen eines Strahls und bewirkt, dass dieser zu einer ausgedehnten Strömung wird, wodurch das Erscheinungsbild einer Schlangenlinie vermieden wird. Wenn der Anschnitt senkrecht zur Wand des Formhohlraums platziert wird, verläuft er auch senkrecht zur Richtung des Anschnitts.

Wellenlinien:

Lösung#1:

Erhöhen Sie die Temperatur der Form auf das gewünschte Niveau. Wenn die Temperatur der Form steigt, nimmt die Schmelzflüssigkeit weiter zu.

Bei kristallinen Polymeren begünstigt eine höhere Temperatur die Homogenität der Kristallisation, wodurch die Sichtbarkeit von Welligkeit minimiert wird.

Lösung#2:

Ändern Sie die Art und Weise, wie der Hohlraum konfiguriert ist. Die Website Schimmelstruktur kann auch für das Auftreten von Wellenlinien auf der Oberfläche des Produkts verantwortlich sein. Ein hoher Widerstand gegen den Schmelzfluss wird beobachtet, wenn die Kanten und Ecken des Formkerns ausgeprägt sind.

Dies führt zu einer Instabilität des Schmelzflusses und damit zur Entstehung von Wellenlinien. Die Anpassung der Kanten und Ecken des Formkerns kann dazu beitragen, das Auftreten von Wellenlinien zu verhindern, indem ein Pufferübergang geschaffen und ein kontinuierlicher Fluss der Kunststoffschmelze aufrechterhalten wird.

Lösung#3:

Ändern Sie das Produkt so, dass es die gewünschte Dicke hat. Die variable Dicke des Bauteils führt zu einem schwankenden Widerstand gegen den Fluss des geschmolzenen Materials, was wiederum zu einem instabilen Fluss des geschmolzenen Materials führt.

Dadurch hat das spritzgegossene Produkt eine gleichmäßige Dicke, was auch dazu beiträgt, das Auftreten von Wellenlinien zu verhindern.

Strahlungslinien:

Lösung#1:

Passen Sie das Profil der Türformen nach Bedarf an. Durch Vergrößerung des Anschnitts oder Umwandlung in einen fächerförmigen Anschnitt ist es möglich, die Flexibilität der Schmelze allmählich wiederherzustellen, bis sie die Kavität der Form erreicht.

Auf diese Weise kann ein Schmelzbruch vermieden werden.

Lösung#2:

 Verlängern Sie den Hauptkanal der Form so weit wie möglich. Es ist möglich, die Schmelze daran zu hindern, sich über den Formhohlraum hinaus auszudehnen, bis sie ihren endgültigen Bestimmungsort erreicht. Tauschen Sie das Gerät gegen ein Gerät aus, das eine deutlich längere Düse hat.

Um das elastische Versagen der Schmelze zu erhöhen, verlängern Sie den Fließweg in die Formkavität. Dadurch wird die Bildung von Strahlungslinien als Folge von Schmelzebruch verhindert.

Fluoreszierende Linien:

Lösung#1:

Bringen Sie die Temperatur der Form auf das gewünschte Niveau. Im Vergleich zur Temperatur der Form kommt es zu einer Verringerung der fluoreszierenden Linien auf der Oberfläche der Produkte, zu einer Beschleunigung der Entspannung der Makromoleküle, zu einer Verringerung der molekularen Orientierung und der inneren Spannung sowie zu einer Verringerung der molekularen Orientierung.

Lösung#2:

Eine Änderung der Struktur des Hohlraums könnte zu einer Erhöhung der Produktdicke führen.

Warum ist das so? Mit zunehmender Produktdicke kommt es zu mehreren Effekten: Die Schmelze kühlt langsamer ab, die Spannungsrelaxationszeit verlängert sich, die Orientierungsspannung nimmt ab, und die Fluoreszenzlinien nehmen ab.

Lösung#3:

Die Nutzung von Wärme, z. B. in einem Backofen oder einem Topf mit kochendem Wasser.

In diesem Szenario stimuliert die Wärmezufuhr die makromolekulare Aktivität, verkürzt die Relaxationszeit und verstärkt die Wirkung der Depolarisation, was letztlich zu einer Verringerung der Anzahl der Fluoreszenzlinien führt.

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Produzieren und lancieren Sie fehlerfreie Spritzgussprodukte mit der Unterstützung der professionellen Hersteller von Prototool:

Beim Kunststoff-Spritzgießen ist die Vermeidung von Fließlinien für die Herstellung eines qualitativ hochwertigen Endprodukts unerlässlich.

Wenn Sie sich mit den häufigsten Ursachen für Fließlinienfehler beim Spritzgießen befassen und mit einem Hersteller oder Lieferanten zusammenarbeiten, der Erfahrung mit der Lösung solcher Probleme hat, können Sie sicherstellen, dass das Endergebnis sowohl eine ansprechende Ästhetik als auch strukturelle Haltbarkeit aufweist.

Hier hilft Ihnen Prototool, Ihre Produkte fehlerfrei zu machen. Von der Prototyp Prototool verfolgt einen präventiven Ansatz, um sicherzustellen, dass im Endprodukt keine Fehler auftreten.

Wenn Sie also auf der Suche nach einem zuverlässigen Mitarbeiter sind, der Ihnen dabei hilft, dass Ihr nächstes Produktionsprojekt fehlerfrei abläuft und die Produkte direkt nach der Produktion auf den Markt kommen, dann sind wir immer für Sie da, um dies zu ermöglichen!

Kontaktieren Sie uns unter Prototool heute!

The post Flow Lines Defect in Injection Molding: Solving and Preventing a Common Injection Molding Defect appeared first on Prototool written by Prototool.

Injection molding weld lines refer to a line on an Spritzgussteil that is generated where the two halves of the mold come together. As a result, the portion has a faint, perhaps undetectable line. 

This line does not normally impact the overall shape or dimensions of the item. Still, it can be seen to varied degrees depending on mold polish, material type, material color, and processing settings. There are numerous ways to make this line less visible on the molded object, but because injection molding relies on a two-part mold, it can never be totally avoided.

This guide will explore the cause, differentiating factors, impacts, and solutions of welding lines in injection molding.

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Factors That Cause Weld Lines:

Weld lines, also known as knit lines, can appear in injection molds due to a number of potential causes. Injection molding weld lines can be caused by several different things, some of which are listed below.

● Inappropriate Temperature

The formation of weld or knit lines in injection molding is significantly influenced by temperature. When the temperature is insufficiently high, there is a risk of premature solidification, leading to the appearance of injection molding weld lines. Temperature issues can arise in different areas, including the mold, Läuferund Spritzgießmaschine.

Proper control and maintenance of the mold temperature are crucial to prevent rapid solidification and promote seamless flow and fusion of the molten plastic, minimizing the occurrence of injection molding weld lines.

Similarly, monitoring and regulating the temperature in the runners and the injection molding machine are important to ensure optimal plasticization and flow, reducing the likelihood of weld line formation. Manufacturers can produce high-quality plastic parts with improved structural integrity and visual appeal by closely managing temperature throughout the injection molding process.

● Pressure

Insufficient pressure can result in a weld line forming during the plastic flow and melting process. This occurs most frequently in the event that the equipment in question is malfunctioning or when the settings on the machine are incorrect. The incorrect design of the mold is another possible cause of this issue.

● Poor Mold Design

Poor mold design, including inappropriate mold Wandstärke and faulty gate placements, is a common cause of weld line formation in injection molding. Inadequate mold wall thickness leads to uneven cooling and hindered plastic flow, resulting in weld lines.

Incorrect gate positions cause multiple flow fronts that struggle to merge seamlessly, creating visible injection molding weld lines. To address these issues, optimizing mold wall thickness and strategically placing gates can minimize weld line formation, improving the overall quality of injection-molded products.

● Resin Speed

The slow flow speed of the molten plastic in injection molding can result in the formation of weld or knit lines. When the plastic flows slowly, it cools unevenly, causing visible lines or seams to appear where the cooled fronts meet.

To prevent these imperfections, optimizing the flow speed is crucial for achieving uniform and rapid movement of the molten plastic, reducing the likelihood of weld or knit line formation.

● Mold Release

Excessive mold release agent application can impact the injection molding process, particularly regarding the required pressure for injecting the resin into the machine. When there is an excessive amount of mold release agent present, higher injection pressures are typically necessary to facilitate the flow of the molten plastic.

However, if the injection speed is not appropriately adjusted to accommodate this higher pressure, it can lead to the formation of weld lines in the final product. Therefore, finding the right balance between mold release agent application, injection pressure, and injection speed is essential to minimize the occurrence of weld lines and ensure optimal product quality.

● Resin Impurity

Lastly, the presence of impurities in the resin used during injection molding can significantly impact the flow characteristics within the mold, potentially resulting in the formation of weld lines in the final product. Impurities in the resin can cause disruptions and irregularities in the flow, hindering the smooth and continuous movement of the molten plastic.

These flow disturbances can lead to the inability of the plastic fronts to merge seamlessly, resulting in the visible formation of weld lines. Therefore, ensuring the purity of the resin and using high-quality materials is crucial to achieving a more consistent and uninterrupted flow, reducing injection molding weld lines’ occurrence, and enhancing the molded product’s overall quality.

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Impact of Injection Molding Weld Lines On Product Quality and Performance:

When you encounter weld lines in injection molded products, it might not seem like a huge deal initially. However, professionelle Hersteller ought to take precautions to avoid them.

Why is that important? Because injection molding weld lines hurt the strength and longevity of the items produced by plastic injection, and as a result, they ought to be avoided.

Precisely, some of the most essential reasons to eliminate weld lines are as follows:

Solutions for Injection Molding Weld Lines

If you’re ever faced plastic sink mark issues in injection molded products, then troubleshooting welding lines can be easier. Simply put, the solution to the injection molding weld lines is similar to the solutions and approaches to reduce Einfallstellen.

Weld Lines vs. Meld Lines: Are They Different?

The two are different Spritzgießfehler commonly found in molded plastic products.

If you’re confused between the two, the distinguishing characteristics are simple. Simply put, the joint angle of the two flows can specifically define the differences between injection molding weld lines and melt lines. When the value of the converging angle is greater than 135 degrees, a melt line will form.

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While a weld line will develop if this angle value is less than 135 degrees, there will not be one if it is greater than this number. Slow flow speed in injection molding can cause weld or knit lines to form. Let’s take a look at the factors that lead to these lines of imperfection.

Summing Up:

While injection molding weld lines can greatly impact your product’s performance and quality, it can often be an overlooked injection molding defect. Hence, the best way to ensure that injection molding welding lines do not impact your entire production line quality is to seek expert help.

Unter Prototool, we ensure that our injection molding production process is conducted with extreme attention to detail and emphasis on maintaining accuracy in every step to prevent common defects like welding lines.

For more details and queries, welcome to connect with our professional team.

The post Analyzing The Occurrence of Injection Molding Weld Lines and Their Solutions appeared first on Prototool written by Prototool.

“Burn marks” are a type of flaw in injection molded parts that manifest as a blackened edge near the very end of the cavity-filling process. Air that becomes trapped in the injection mold’s cavities causes burn marks.

As the plastic was pumped into the mold, it compressed the air inside the cavities to the point where diesel fuel ignited. The charred leading edge of the molten plastic is responsible for the black color.

When air is trapped during the injection (or filling) stage of the molding cycle due to flaws in the design of the plastic part or the injection mold, burn scars might result. As a result of the compression, the air temperature rises.

It burns at high enough temperatures, leaving only carbon residue on the component. We refer to those dark scars as burns, as shown in Fig 1 below.

Unfortunately, burn spots in injection molding are more than just an issue in the appeal of the product. Instead, these marks also degrade the material and mold qualities.

As a result of this deterioration, the component’s structural integrity is usually compromised, and the part eventually fails.

These flaws in plastic injection molding can be remedied by a skilled manufacturer before the pieces even reach you.

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But how common are they? And what is the impact of burn marks in injection molding? What approaches do professional injection molding service providers use to troubleshoot this defect? Let’s go ahead and analyze burn marks in injection molding in more depth.

The Main Cause of Burn Marks in Injection Molding:

Mold can become a source of burn marks if uncontrolled conditions allow it to grow. The molten material flows in a laminar state when it is injected into the cavity.

The rate at which injection molding is performed picks up, to some extent, disrupting the flow condition. Burn marks are left on the surface of a plastic component whenever it is formed in turbulent conditions.

The injection speed should be slowed down to avoid burn scars and maintain control of the flow condition. Burn marks are fairly easy to develop on plastic molded parts when subjected to high melting temperatures.

Therefore, the back pressure should be lower than 2 MPa, and the screw speed should be lower than 90 RPM. The specialists in injection molding advocate finding a solution to the burning problems in the molded parts.

A prolonged rotational period contributes to the production of excessive frictional heat during the injection molding process. To fix this issue, you can increase the speed of the screw and extend the length of the molding cycle.

 It is beneficial to use raw material with a low level of lubrication, and helps reduce back pressure.

The high resin temperature is responsible for transforming the material into charring as it progresses. You can fix this problem by ensuring the heater bands operate correctly. Check the temperature, and if you discover that the melt temperature is too high, adjust it. You can bring it down for more efficient processing.

Because the Fass and the screw aren’t functioning properly, the parts could have a dark tint and striations that look like specs. When we utilize the anti-reverse ring in the molding machines, you may need to replace the barrel and the screw to fix the problem.

It can become a cause of retention, as well as create discoloration and decomposition and melt. Burn marks of a dark brown or black color are produced when molders inject this discolored melt into the mold’s cavity.

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In this scenario, you can eliminate this problem by cleaning the nozzle screw system well. It would be best if you went with a high-velocity resin. It is recommended that you use a machine with a long diameter and low pressure for the entire process.

Furthermore, the cause of burn marks may be mainly the breaking down of the substance, but they’re still a mystery. This takes place as a result of excessive heating and rapid injection speed.

It may be because of a combination of a high melt temperature and a flow route that is too narrow. The fast speed of the screw affects the material as well and might be the cause of burn marks.

Burn markings are a common problem in injection molding, and one of the primary causes is the excessive heating of the trapped air. After the filling procedure, you can notice some burn marks. It’s possible that the speed was too high for injection molding to work properly. Reduce the pressure and take control of the rate at which the container is filled to find a solution to this problem.

Incorrect venting is another source of air trapping and burn marks at the end of the filling, which can occur when the filling is baked. The injection rate might be slowed down, which could effectively solve this problem. Air can become trapped in the runner system due to the high injection speed and pressure.

Compressing air will generate polymer that will degrade on the surface in the vicinity of the blind spot. One solution would be to install an adequate venting system that would assist in releasing the air trapped inside the tarp.

In fact, they play an extremely significant role in the blind area as well as close to the conclusion of the flow path. The venting size for the crystalline polymer is 0.025 millimeters, while the correct size for the amorphous polymer is 0.038 millimeters.

The size of your nozzle and Tor both have a role in producing flaws in your completed products. A nozzle and gate size that is too tiny can result in black streaks appearing in the molded pieces. You can reduce the amount of resin that flows out by opening the mouth of the nozzle or the opening. It’s possible that this will solve the problem.

Failure of mold growth can potentially become the source of numerous issues. It ought to give careful thought to the matter. In this regard, the mold gate type and location are of the utmost importance. You need to make sure that you use the right amount of release agent, and the surface of the cavity in the mold should have a glossy finish.

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Another cause of burn marks is the failure of mold, which is one of the primary reasons. Therefore, the functioning of the mold needs to be improved to resolve this issue.

Failure of mold can be caused by several circumstances, including the following:

• Because of releasing agents, mold can block vents in buildings.
• Insufficient capacity for venting the mold.
• Poor design and location, as well as a rapid rate of filling
• Burning can also be caused by excess grease and the breakdown of grease.
• Compression leads to the production of high temperatures, which acts as a gas trap and causes the resin to burn.

To resolve all of these concerns, you need to ensure that the clamping force is modest. There shouldn’t be any obstacles, and the mold ventilation should improve.

Brief Overview of Common Issues Leading to Burn Marks + The Solutions:

Summing Up:

Whether you’re new to the production sector or have been in the industry for a long, you might be well familiar with the fact that injection-molded parts often have flaws like burn marks.

This defect is a potential source of component deterioration, mold growth, and complete product failure. Even though burn marks are frequent in plastic injection molding, they can be avoided with the right knowledge and by collaborating with the best injection molder.

By referring to the guide above, you can closely analyze the cause of burn marks and keep them from occurring and affecting the final production quality of your product.

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The post A Deep Analysis of Burn Marks in Injection Molding appeared first on Prototool written by Prototool.