How to troubleshoot quality problems in injection molded products?

(1) The shape and size of the product are incomplete

1 When the temperature of the melt plasticization is low, the temperature of the barrel should be increased.

2 If the holding pressure is insufficient or the holding time is relatively small, it should be adjusted appropriately to observe the effect.

3 Insufficient amount of injection melt, or it may be caused by severe wear of the outer diameter of the screw or failure of the check valve.

4 The nozzle is in poor contact with the die bushing port, resulting in more flash during injection.

5 The nozzle part temperature is low.

6 The injection speed is low, and the injection speed should be increased appropriately.

7 The screw back pressure is low, and the quality of raw material plasticization is not uniform.

8 The mold heating temperature is low or the temperature of each part is uneven, and the temperature difference is large. Check whether the heater is damaged or properly adjusted.

9 Melt flow path problem. Such as low flow path temperature, small cross-sectional size or rough surface.

10 The structural size of the product is unreasonable, and the wall thickness of some parts is too small.

(2) The shrinkage of the product's external dimensions is unstable

1 The injection melt pressure is small and should be increased appropriately.

2 Low holding pressure or insufficient holding time.

3 The temperature of the barrel is high, and the temperature of the melt is high when plasticizing. The temperature of the barrel should be lowered appropriately.

4 The back pressure of the screw is low, which causes the plasticization of the melt to be uneven. It is necessary to increase the back pressure of the screw.

5 mold temperature effects. The effect should be properly adjusted and observed, mainly because the mold temperature is high and the cooling time is increased.

6 The nozzle has a small aperture and should be appropriately enlarged.

7 The injection melt rate is slow and should be adjusted appropriately.

8 The amount of injected melt is insufficient.

9 The position of the mold gate is not reasonable.

10 The shape design of the product is unreasonable, resulting in uneven local stress.

(3) It is difficult to release the product

1 The melt injection pressure is high and the injection pressure should be reduced.

2 If the melt temperature is too high, the barrel temperature should be reduced or the screw speed should be reduced.

3 The raw material has a high moisture content and should be dried.

4 The mold temperature is low or the temperature difference between the parts is large.

5 The surface of the mold-formed product is rough and the draft is not enough. It should be repaired and modified.

6 The pressure holding and cooling time is short, and the cooling time should be extended appropriately.

7 The amount of release agent coating is insufficient or the coating is not uniform.

(4) Products have flash

1 The mold clamping of the two halves is not tight or the joint surface is rough, which should be repaired and improved.

2 The melt injection pressure is too high, and the injection pressure should be appropriately reduced.

3 The clamping force is insufficient, and the clamping force should be improved.

4 The melt temperature is too high and the temperature should be lowered.

5 If the amount of molten material injected is too much, it should be adjusted to reduce the injection time, the amount of material used or the injection speed.

6 The mold temperature is too high and the mold temperature should be lowered.

(5) The product is easily broken when demolded

1 The plasticization of raw materials is uneven, and the back pressure of the screw should be properly increased.

2 The mold temperature is low and the mold temperature should be increased.

3 If the ejector rod is not working properly or the ejection force is uneven, the rupture site should be found and the working position of the ejector rod should be properly adjusted.

4 The mold release angle of the product mold is not enough, the mold should be improved, and the draft angle should be increased.

5 When there is a vacuum phenomenon in the parts where the product is demoulded or the mold structure is unreasonable, local stress concentration of the product occurs, and the mold needs to be redesigned.

6 The side slider is not in harmony with the mold opening action or the ejection action. The mold should be modified.

7 The surface of the forming mold is rough and should be reground to reduce the roughness of the forming surface.

8 The release agent coating is uneven or insufficient.

(6) There is a weld mark on the surface of the product.

1 The plasticization of raw materials is uneven, and the back pressure of the screw should be increased.

2 The mold temperature is low, and the mold temperature should be increased appropriately.

3 The injection pressure and speed are low and should be appropriately increased.

4 The nozzle has a small aperture and should be enlarged to increase the amount of melt injected per unit time.

5 The cross section of the melt flow channel is small, affecting the flow rate, and the pore size of the melt flow channel should be increased.

6 The water content in the raw material is too high, and the raw material should be dried to make the water content smaller than the allowable water content of the raw material.

(7) The surface of the product has ripples

1 The raw material plasticizing and melting is not uniform, and the barrel temperature should be increased or the screw back pressure should be increased.

2 The mold temperature is low, and the mold temperature should be increased or the temperature of each part should be balanced.

3 Adjust the melt injection pressure, the injection pressure is insufficient or high will affect the apparent quality of the product.

4 The pressure-holding and cooling-curing time is short and should be extended appropriately.

5 The moisture content of the raw materials is too high and the raw materials should be dried.

6 The injection speed of the melt is unreasonable. Note that the injection speed is too fast or too slow to affect the apparent quality of the product.

7 The molding surface of the mold is rough and should be ground to reduce its roughness.

(8) The product has bubbles or silver

1 The raw material has a high water content, and the raw material should be dried to make the water content of the raw material less than the allowable water content.

2 Additives in raw materials are not resistant to high temperatures and should be replaced.

3 If the temperature of the barrel is high or the residence time of the raw material in the barrel is too long, the temperature of the front section of the barrel should be lowered or the injection molding machine of smaller size should be used instead.

4 The screw back pressure is small, and the screw back pressure should be properly increased.

5 Low holding pressure or short holding pressure and cooling time. The holding pressure should be increased to extend the pressure holding and cooling time.

6 The mold temperature is low, and the mold temperature should be increased appropriately.

7 The injection pressure is too high and the injection pressure should be reduced.

8 The injection speed is too fast and the injection speed should be reduced.

(9) The surface gloss of the product is not good

1 The quality of plasticizing and melting of raw materials is uneven, and the barrel temperature or screw back pressure should be appropriately increased.

2 The water content in the raw material is too high, and the raw material should be dried and treated so that the water content in the raw material does not exceed the allowable water content of the raw material.

3 The surface of the cavity of the forming mold is rough or has water droplets, which should be polished to improve the surface brightness of the cavity.

4 If the additive in the raw material is improperly added, it should be adjusted and replaced.

5 The raw materials are not clean and have impurities.

6 The mold temperature is low, and the mold temperature should be increased appropriately.

7 The melting channel and gate diameter of the molding die are small, the flow resistance of the melt is large, and the mold is poorly exhausted, and the mold should be modified.

(10) Deformation of injection molded products

1 The structural design of the product is unreasonable, the shape and thickness are asymmetrical, and the design should be improved.

2 The pressure holding and cooling time is short, and the cooling time should be extended.

3 The temperature between the parts of the forming mold is uneven, and the temperature difference is too large. The temperature control balance should be improved to make the temperature of each part uniform.

4 The ejection force is not uniform, and the working position of the ejector rod should be adjusted.

5 The position of the gate is not reasonable. The gate position should be changed appropriately.

6 The injection melt pressure and speed are high and should be reduced appropriately.

(11) Products have black spots or black stripes

1 The barrel cleaning is not clean, there is decomposition of residual material, the barrel should be disassembled, and the barrel and screw residue on the screw should be thoroughly cleaned.

2 There are impurities in the raw materials, and the replacement of raw materials should be checked.

3 The nozzle aperture is small, the gate aperture is small, the melt temperature is high, the injection pressure is high, and the speed is fast. The melt is likely to cause yellowing or decomposition due to high temperature. The quality of the melt should be adjusted and observed. cause of issue.

4 There is a stagnation area in the barrel or at the nozzle part, which causes the melt to decompose and black spots or streaks appear. The barrel and nozzle should be disassembled, the stagnation area should be found, and the grinding should be carried out.