Common Problems

frequently asked questions

Undesirable Categories

Cause analysis

Ways for problem solving


Lacking of mold clamping force.

Improve the clamping force.

Mold deformation

Repair Molds

The mobility of materials is too high.

Select materials with low mobility.

Improper injection pressure and other processes.

Adjust the injection pressure and other processes.

Weld mark

Improper setting of injection molding process.

Improve the material temperature, mold temperature, and adjust the injection speed and 


Poor ventilation

Improve the injection pressure, add or expand the exhaust passage.

There is foreign body in the cavity.

Clean the cavity surface.

Insufficient material liquidity.

Select materials with high mobility.

Big molding shrinkage

Insufficient injection quantity and cavity filling.

Increase the injection quantity

The gate size is too small to be filled.

Increase the gate size.

Insufficient injection pressure and material entry.

Improve injection pressure

Excessive material temperature or mold temperature.

Reduce the temperature of material barrel and mold.

Unreasonable design of mold or parts.

Modify the design

Rough floating fiber on surface

The surface of mold is rough and scaling. 

Improve the cleanness of mold.

There are volatile substances in the raw materials

Sufficient dry ingredients.

Poor ventilatio

Add exhaust channels.

The mold temperature is too low

Improve mold temperature.

Improper setting of injection molding process.

Adjust the injection speed, pressure and prolong the pressure time.

The thick wall is cracked

Excessive internal stress.

Adjust molding process and post-treatment process

Improper setting of mold temperature and injection 


Reasonable adjustment of mold temperature and temperature

Improper use of lubricants and molds.

Reduce the dosage of mold release agent.

Improper positioning or unpreheating of embedded parts.

Optimize the design and preheat the embedded parts.

Improper selection of materials.

Select the material suitable for thick wall forming.

Injection molding is insufficient

The temperature of material barrel or nozzle is too low or 

too high.

Adjust the nozzle temperature.

The mold temperature is too low or too high.

Adjust the mold temperature.

The product volume exceeds the maximum injection 

amount of injection molding machine.

Check the relationship between injection volume and product volume.

Insufficient injection or slow injection.

Increase the injection pressure.

The runner gate is too small

Expand the gate

The injection time is too short.

Extend the molding cycle

The exhaust is not good enough to prevent boring 

mold filling.

Remove blocking materials or modify molds.

Air bubbles

Excessive moisture or volatiles in raw materials.

Ensure the raw materials are fully dried.

The mold temperature is too high or too low.

Adjust the mold temperature.

The injection pressure is too light or the injection speed is too fast, and the material is mixed into the gas.

Improve injection pressure and adjust infusion speed.

Pressure release too early

Increase the pressure holding time

Flowing marks on the 

surface of materials

The temperature of material or mold is too low.

Raise the temperature of the drum or mold.

Low injection pressure and slow speed.

Increase injection pressure and speed.

Poor exhaust of the mold.The gate is too small.

Modify the mold vent tank.

Reduce or increase the gate.

Dimensional instability

The pressure transmission system of machine is unstable.

Maintain the equipment.

The molding cycle is inconsistent.

Strictly control the molding cycle.

Bending or wearing of mold positioning bar.

Repair the mold to make clamping closed.

Uneven loading of materials

Mandatory quantitative feeding.

Uneven mixing of recycled materials and new materials

Ensure uniform mixing.

Demolding difficulty

The mold is not clean enough, with scratches or marks.

Improve the precision of mold machining.

There is not enough inclination of the mold, and the 

inlaid seams are too large.

Improve the mold design.

No air inlet of the core mold.

Increase the exhaust gap.

Poor structure of ejection device.

Overhaul the ejection mechanism.

The injection pressure is too high, the time is too long.

Reduce the injection pressure and shorten time.

The mold temperature is not suitable.

Improve mold temperature or shorten cooling time when die core surface is difficult to remove.

Sticky mold, difficult to remove,unevenly or invalidated.

Select effective release agent and apply all.

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