Causes of plastic injection molding failure

Insufficient filling

[1] The volume of the molded product is too large 

[2] Flow channel and gate are too small

[3] Low nozzle temperature 

[4] Low material temperature or ejection pressure

[5] The fluid flow distance in the cavity is too long

[6] Mold temperature is low

[7] Injection speed is slow

[8] Low material supply

[9] Poor air venting

Overflow of material

[1] Insufficient clamping force

[2] Bad mold

[3] Impurities on the mold surface

[4] Excessive projection area of molded products

[5] Excessive temperature of the material

[6] Excessive material supply

[7] High injection pressure

Pore

Cause: When the material is sufficiently dry, it is caused by volatiles or air; most of the time, it occurs at the position of the product glue thickness, which is actually a vacuum bubble caused by the shrinkage of the material

[1] The runner or gate is too small

[2] The wall thickness difference of the finished product is large

[3] High temperature of the material

[4] Long flow distance from the gate

[5] Premature release

[6] Low injection pressure

[7] Short cooling time

[8] Insufficient pressure retention

Ripple

[1] Poor material flow

[2] Low mold temperature

[3] Inlet gate too small

Silver streaks

[1] Moisture or volatile components

[2] Excessive temperature of material

[3] Low mold temperature

[4] Poor exhaust

[5] Poor design of molded products or molds

[6] Moisture or volatile components on the mold surface

[8] Mixing of entrained materials

[9] Improper operation of the propeller

Darkening of the surface

[1] Excessive lubrication or volatile components

[2] Excessive release material

Fusion line

[1] Temperature of material

[2] Improper design of gate

[3] Too many volatile components or release agents in the material

[4] Rapid solidification of the material 

[5] Poor design of molded parts

Air bubbles

[1] Gate or runner is too small 

[2] Low injection pressure

[3] Excess moisture

[4] Poor design of molded products

[5] Poor venting

Black streaks and burn marks

The actual phenomenon is the decomposition and scorching of the material by the action of high temperature and pressure.

[1] Overheating of the material

[2] Defective molding machine

[3] Poor design of mold Small gate Poor venting

Cracking

It is actually caused by the internal stress generated by the molecular structure inside the material when it is injection molded into a specific shape from an irregular state.

[1] Excessive injection pressure

[2] Poor flow of material

[3] Push tappet nail in the thick layer part

[4] No trace of exhaust

[5] Poor adjustment of holding pressure

[6] Large thermal cracks

[7] Chemical erosion

Overflow of material from mold

[1] Improper design of gate

[2] Fast ejection speed

[3] Low temperature of material

[4] Low temperature of mold

Bending

[1] Inadequate cooling

[2] Poor release of straight sprue

[3] Uneven cooling 

[4] Inappropriate injection pressure

[5] Improper gate position

[6] Mold core bias

[7] Uneven flow distance from the gate

Poor mold release

[1] High injection pressure

[2] Poor adjustment of mold temperature

[3] Poor mold design, poor ventilation from the core, insufficient strength of the mold　

Poor release of the straight sprue

[1] Poor installation of the mold

[2] Bad shape of straight gate

Bad edge stacking of material

[1] Poor drop of hopper 

[2] Excessive amount of crushed recycled material mixed in

[3] Excessive external lubricant