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Why is there a molding defect and how to solve the common defects of moulding?

Oct 26, 2018



Surface blistering or internal bulging1. The volatile content in materials is too large
2. Mold curing incomplete
3. The mold temperature is too high to vaporize or decompose certain components in the material
4. Slow exhaust operation to solidify the surface.
1. Fully preheat the material
2. Moderately increase the mold temperature or extend the pressure keeping time
3. Mold temperature reduction
4. Vent at an appropriate rate.
Shortage of material1. Uneven weight of material
2. Poor material mobility
3. Too much mold release agent
4. Operating too fast.
1. Increase material weight appropriately
2. Generally take preheating and increase molding pressure
3. The mold shall be coated evenly with appropriate amount of demoulding agent
4. Properly adjust the mold closing temperature and pressure timing
Crack1.The concentration of resins results in uneven stress distribution and cracks
2.Too much pressure on the mould
1.Distribute the material evenly
2.Reduce pressure appropriately
Fissures1.Improper mold design or processing resulting in stuck mold phenomenon
2.Metal insert and mold plastic shrinkage factor is different, resulting in stress failure
3.The content of moisture and volatile matter in materials is too large
4.Solidified spent ambassador material shrinkage rate increases
Improper die design or poor ejection device
5.The thickness of each part of the workpiece varies too much.
1.Modification of die design, reasonable design of demoulding structure, to ensure the average ejection force
2.Select suitable insert material, and increase the thickness of moulded products
3.Preformed molding compound
4.Lower mold temperature or shorten the holding time
5.Correct die design, adjust the size and position of ejector bar
Alter design




Warp1.Undercuring of presswork
2.The product design is unreasonable, such as the thickness of the wall is not symmetrical, the difference is too large
3.The parts are too soft to mold
4.Material shrinkage is too high
1.Improve curing conditions
2.Improved product design
3.Improve materials and speed of molding
4.Using low shrinkage materials or improved process methods
The surface of the product is dull1.Cavity surface finish is not enough
2.Mold temperature is too low
3.Mold plastic to damp or low molecular volatile content too much
4.Closed mold too fast.
1.Polish or polish the surface of the cavity
2.Adjust die temperature
3.Preheat molding powder to improve exhaust conditions
4.Slow down the mold so that the volatility is clear.
Sticking the mold1.Cavity surface finish is poor
2.Short pressure holding time and low molding temperature
1.Polish or polish the surface of the cavity
2.Properly adjust the molding process parameters
Poor electrical performance1.Incomplete curing
2.Mold plastic is too big with water and volatiles
1.Improve curing conditions
2.Preheat remove moisture and volatiles, prepressing
Poor mechanical properties1.Incomplete curing
2.Capacity is insufficient
3.Insufficient molding pressure
4.Insufficient deflation
1.Take reasonable curing conditions
2.Increase the quantity of material appropriately
3.Increase the pressure
4.Improve venting conditions
Uneven surface color1.The mold temperature is uneven and local too high
2.The mold temperature is too high to decompose or age the material
3.Uneven mixture
1.Adjust mold temperature uniformity
2.Reduce the die temperature
3.Enhanced blending
Rough surface1.Incomplete curing
2.Material mobility
3.Mold temperature is too high or mold closing is too slow, so that part of the 4.material solidify in advance
5.Improper molding operation, too fast
6.Moulded plastics absorb moisture
1.Improve curing conditions
2.Regulate fluidity, high frequency preheating 3.appearance is better
4.Lower the mold temperature and close the mold quickly
5.Generally use low pressure slow - closing die, pre - pressure a few seconds after pressure
6.Mold plastic heating and drying
Surface white spot1.Too much low shrinkage
2.The low shrinkage agent is not suitable
3.Color lake is not applicable
1.Adjust the dosage of low shrink agent
2.Select suitable low shrinkage agent
3.Change to pigment that is suitable for moulding