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Reasons and countermeasures of TPE injection molding defects

Reasons and countermeasures of TPE injection molding defects

Reasons and countermeasures of TPE injection molding defects

Information
 
 
Question Possible cause Solution
Lack of glue There is residual air due to insufficient exhaust 1. Check for obstacles in the exhaust system
2. Check the position of the exhaust system
3. Enlarge the vent hole
4. Increase or decrease injection speed or injection pressure
Runner system 1. Check the clogging of the gate
2. Enlarge the gate
3. Enlarge the runner
The melt or mold temperature is too low 1. Increase the temperature of the barrel and nozzle
2. Increase mold temperature
3. Increase injection speed
4. Increase screw speed
Injection volume 1. Increase injection volume
2. Improve the melt buffer layer
Dumps, bubbles
(not to be confused with insufficient exhaust)
The holding pressure is too low Increase the holding pressure
The melt or mold temperature is too high 1. Reduce the temperature of the barrel and nozzle
2. Reduce mold temperature
3. Reduce the screw speed
scorched The melt or mold temperature is too high 1. Reduce the temperature of the barrel and nozzle
2. Reduce mold temperature
3. Reduce the screw speed
Abnormal heating circle Check thermocouple and heating strip
Mold design 1. Enlarge the vent hole
2. Check for obstacles in the exhaust system
3. Add a vacuum system to the exhaust system
4. Check the position of the exhaust hole
Peculiar smell or yellowing The melt or mold temperature is too high 1. Reduce the temperature of the barrel and nozzle
2. Reduce mold temperature
3. Reduce injection speed
4. Reduce screw speed and back pressure
5. Check the temperature of the runner (if hot runner is used)
Flash edge Injection pressure/speed is too high 1. Reduce injection pressure
2. Increase clamping pressure
3. Reduce injection speed
The melt or mold temperature is too high 1. Reduce the temperature of the barrel and nozzle
2. Reduce mold temperature
3. Reduce injection speed
Product deformation Too many orientations 1. Increase melt and mold temperature
2. Reduce injection speed
Overfilling 1. Reduce back pressure
2. Coordinate the injection time and the time when the mold is full
Uneven mold filling 1. Change the gate position
2. Make sure the mold temperature of each cavity is the same
3. Improve injection speed and back pressure
Black spots or particles are unevenly dispersed Contaminated 1. Use high-flow PP, HDPE to wash the barrel
2. Check if the base material of the color masterbatch is PP, PE instead of PVC
Sticky mold Mold parts are too hot 1. Reduce the temperature of the barrel and nozzle
2. Reduce mold temperature
3. Increase the cooling time
Overfilling Reduce the injection volume and find out the exact modulus filling
There is a problem with the mold design 1. Increase the oblique angle
2. Carry out non-stick mold surface treatment
3. If necessary, use etched molds
There is a mold lock mark at the gate Water vapor 1. Dry raw materials
2. If it is an exhaust type screw, check if there is any obstruction in the exhaust port
3. Add a vacuum device to exhaust
Flow marks The melt or mold is too cold 1. Increase the temperature of the barrel and nozzle
2. Increase melt and mold temperature
3. Increase injection speed
4. Increase screw speed and back pressure
5. Check if the screw is suitable
Mold design issues 1. Change the gate position
2. Enlarge the gate
3. Enlarge the runner
4. Increase the blocking area in the flow channel
Vacuum bubble
(not to be confused with the dissatisfaction mold)
The melt is cooling too fast 1. Increase mold temperature
2. Increase screw speed and back pressure
Water vapor 1. Dry raw materials
2. If it is an exhaust type screw, check if there is any obstruction in the exhaust port
3. Add a vacuum device to exhaust
Back pressure is too low Increase back pressure
Poor adhesion
(Not firmly attached)
The molding or mold temperature is too low Increase molding or mold temperature
The holding pressure is too high
(Make the TPE and the cooled semi-finished product misaligned on the joint surface)
Reduce the holding pressure
Injection speed is too low Increase the injection speed
Use lubricant Do not use lubricants
During secondary molding, there is oil or dust on the semi-finished product Keep the surface of semi-finished products clean
(If necessary, please wear white gloves for operation)
The semi-finished product is too cold during secondary molding Preheat the semi-finished product
(Note: After heating, the surface temperature can only reach 80-100°C, and the preheating process can only last for a short time, especially when the hard part is a semi-crystalline material, you need to pay more attention to the above points)

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