Common defects in thermoplastic injection molding and their causes?
1. Insufficient product filling
1) the temperature of the material barrel, nozzle and mold is low
2) insufficient feeding amount
3) too much material remains in the barrel
4) the injection pressure is too low
5) the infusion speed is too slow
6) the size of runner and gate is too small, the number of gate is not enough, and the position of cut gate is not appropriate
7) bad exhaust in the cavity
8) the injection time is too short
9) the pouring system is blocked
10) poor mobility of plastics
2. Products have overflow edges
1) high temperature of material barrel, nozzle and mold
2) too much injection pressure and too little clamping force
3) the mold is not tightly closed, and there are sundries or molds
4) bad exhaust in the cavity
5) plastic is too mobile
6) excessive amount of feeding
The product has bubbles
1) the plastic is not dry enough and contains moisture
2) plastic decomposes
3) the injection speed is too fast
4) the injection pressure is too low
5) please keep the temperature too low and the mold filling is not complete
6) bad exhaust of mold
7) take air from the feeding end
4. Product depression
1) insufficient feeding amount
2) the material temperature is too high
3) the difference between wall thickness and wall thickness of products is too large
4) too short time for injection and pressure protection
5) the injection pressure is too low
6) the injection speed is too fast
7) improper location of gate
5. The products have obvious fusion lines
1) the material temperature is too low and the plastic has poor fluidity
2) the injection pressure is too low
3) the infusion speed is too slow
4) the mold temperature is too low
5) bad exhaust in the cavity
6) plastics are contaminated
6. The surface of the product is silvery and corrugated
1) plastics contain water and volatile matter
2) the material temperature is too high or too low
3) the injection pressure is too low
4) the size of runner and gate is too large
5) the temperature of the insert before preheating is too low
6) too much internal stress
There are black spots and stripes on the surface of the product
1) plastic decomposes
2) the speed of the screw is too fast and the back pressure is too high
3) the nozzle does not fit well with the main channel, resulting in material accumulation
4) bad exhaust of mold
5) the plastic is polluted or brought into the sundries
6) uneven particle size of plastic
8. Warping deformation of products
1) the mold temperature is too high and the cooling time is not enough
2) the thickness of products varies greatly
3) improper location of gate and inappropriate number of gate
4) improper position and uneven force
5) the orientation of plastic molecules is too great
9. The dimensions of products are unstable
1) unstable feeding amount
2) it is true that the size of plastic particles is not uniform
3) the temperature of the material barrel and nozzle is too high
4) the injection pressure is too low
5) insufficient time for mold filling and pressure protection
6) improper size of gate and runner
7) improper mold design size
8) the mold design size is not accurate
9) deformation or wear of push rod
10) the electrical and hydraulic systems of the injection machine are unstable
10. Product adhesives
1) the injection pressure is too high and the injection time is too long
2) the mold temperature is too high
3) the size of gate is too large and the location of gate is not appropriate