Translation:

With the increasing popularity of TPE materials in injection molding, more and more production processes have been mentioned. Many friends have summarized the common issues and solutions encountered during TPE material processing. Today, we will consolidate some articles from the internet and share them with you. We hope you can bookmark this for quick reference when dealing with customer issues.

I. Deformation of Finished Products after Ejection

Possible Causes:

1. Insufficient cooling time;
2. Too fast mold opening speed causing deformation due to forceful ejection;
3. Defective product structure;
4. Excessively high mold temperature resulting in inadequate cooling.

Solutions:

1. Extend the cooling time;
2. Slow down the mold opening speed;
3. Modify the mold;
4. Reduce the mold temperature.

II. Jetting Marks

Possible Causes:

1. Too fast injection speed preventing instantaneous venting of air in the mold cavity;
2. Moisture content in the raw material;
3. Excessively high molding temperature causing material decomposition;
4. Air entering the feed tube.

Solutions:

1. Reduce the injection speed to allow smooth venting of air in the mold cavity;
2. Dry the material;
3. Lower the molding temperature;
4. Reduce the temperature at the rear section of the feed tube and increase pressure.

III. Flashing

Possible Causes:

1. Excessive pressure causing the mold-opening force to exceed the clamping force, forcing the mold open;
2. Excessively high injection and holding pressures;
3. Too fast injection speed and high material temperature;
4. Clogged mold vents.

Solutions:

1. Decrease pressure and increase clamping force;
2. Lower injection and holding pressures;
3. Reduce injection speed and material temperature;
4. Clean the mold.

IV. Insufficient Filling

Possible Causes:

1. Insufficient injection pressure and too slow injection speed;
2. Excessively low molding temperature and small runner size;
3. Incomplete venting of air in the mold cavity;
4. Too short injection time and insufficient shot volume.

Solutions:

1. Increase injection pressure and speed;
2. Raise the molding temperature and modify the runner;
3. Add vents;
4. Extend the injection time and increase the shot volume.

V. Weld Lines

Possible Causes:

1. Insufficient injection pressure and speed, small gate and runner size;
2. Excessively low molding and mold temperatures;
3. Inadequate venting at the confluence point and lack of overflow wells;
4. Excessive use of mold release agents.

Solutions:

1. Increase injection pressure and speed, modify the gate and runner;
2. Raise temperatures, increase backpressure, or speed up screw rotation;
3. Add vents and overflow wells at the confluence point;
4. Reduce the use of mold release agents.

VI. Poor Gloss of Finished Products

Possible Causes:

1. Too slow injection speed, insufficient injection pressure, and low mold temperature;
2. Moisture or grease contamination in the mold cavity;
3. Poor mold surface polishing or small gate and runner size;
4. Insufficient shot volume or moisture content in the raw material.

Solutions:

1. Increase injection speed, pressure, and mold temperature;
2. Wipe clean;
3. Modify the mold;
4. Increase injection pressure, speed, extend the injection time, or dry the material.

VII. Flow Marks

Possible Causes:

1. Too high or low injection pressure, too fast or slow injection speed;
2. Short holding time or small gate size;
3. Low mold and gate temperatures;
4. Poor material melting.

Solutions:

1. Adjust injection pressure and speed appropriately;
2. Increase holding time or enlarge the gate;
3. Raise temperatures;
4. Raise temperatures, increase backpressure, or speed up screw rotation.

VIII. Cracking of Finished Products after Ejection

Possible Causes:

1. Low material or mold temperature;
2. Insufficient draft angle or improper ejection method;
3. Small gate size;
4. Insufficient draft angle.

Solutions:

1. Increase temperatures;
2. Modify the mold;
3. Modify the mold;
4. Modify the mold.

IX. Rough Surface of Extruded Products

Possible Causes:

1. Excessively low molding temperature;
2. Low mold temperature.

Solutions:

1. Increase temperatures and screw rotation speed;
2. Raise the mold temperature.

X. Lumps on the Surface of Extruded Products

Possible Causes:

1. The feed tube is not cleaned properly, containing impurities;
2. Carrier of additives such as colorants not used as required.

Solutions:

1. Clean the feed tube;
2. Identify the appropriate colorant.

XI. Insufficient Extrusion Volume

Possible Causes:

1. Insufficient feed tube temperature;
2. Impurities in the die or low screw speed.

Solutions:

1. Increase die temperature;
2. Clean the die or increase screw rotation speed.

XII. Swelling of Extruded Products after Ejection

Possible Causes:

1. Excessively low die temperature or too fast screw speed;
2. Material feed restricted too quickly.

Solutions:

1. Increase die temperature and reduce screw speed;
2. Adjust the material restriction device.

XIII. Generation of Large Amounts of Gas During Extrusion

Possible Causes:

1. Excessively high melt temperature;
2. Impurities in the feed tube.

Solutions:

1. Lower the melt temperature;
2. Clean the feed tube.

XIV. Dents on the Surface of Extruded Products

Possible Causes:

1. Moisture content in the raw material;
2. Excessively high melt temperature and too fast screw speed.

Solutions:

1. Dry the material;
2. Lower the melt temperature and screw speed. (Article sourced from the internet)