common questions in plastic injection 3

common questions in plastic injection 3

21. Setting of release.

 Correct loosening position = moving position of rubber ring + offside distance of screw.

22. Importance of setting the release position

 Too large setting of the release position will cause oxygen absorption of the returned material, which will oxidize the rubber material and generate bubbles. The position setting is too small, so that the pressure in the barrel is large, the shear force is too high, so that the rubber material decomposes, and the nozzle salivates. The position error shall not exceed 0.4mm.

23. Setting of glue position

 Glue position = product weight / (maximum stroke / maximum glue amount)

24. Main advantages of gas assisted injection molding (GAM)

 It can empty the core of thick material and make hollow pipe fitting, which can save material and shorten cycle time.

 When the plastic is cooled and solidified, the gas can compensate the volume shrinkage of the plastic by expansion.

 Reduce the internal stress of molding products, improve the stability of shape, eliminate deformation and warpage.

25. The outer diameter of the piston rod is small in the middle and the two ends are big problems?

  Due to the uneven shrinkage of the overheated products of the middle hole needle, the piston rod has a small outer diameter in the middle and two big ends. The middle hole needle cocoa is made of phosphor copper material with fast heat dissipation, and the mold exhausts air in the middle part of the product.

26. Cracking after silk screen printing on spherical surface

 Due to the stress on the surface of the product, the cracks are caused after screen printing. The stress can be eliminated by annealing.

27. The edge of the water port of the spectacle frame is easy to break

 The residual internal stress at the water port with large injection pressure and holding pressure causes the product to break easily. Try to reduce the injection pressure and holding pressure, and properly increase the mold temperature to solve the problem.

28. It is easy to crack when the four columns of the electrical shell are screwed

 Due to the water line in the column, the assembly column of the product is easy to crack, the mold increases the exhaust, increases the mold temperature appropriately, and speeds up the glue injection speed to reduce the water line.

29. Product deformation

The product deformation is mainly caused by the imbalance of heat shrinkage, or by the internal stress of the product itself.

30. Bubbles in transparent PC shell

If the raw material is not dry enough, the product is uneven in thickness, the mold exhaust is poor, and the raw material is easy to decompose, it may cause product bubbles. Fully dry, increase the mold exhaust, and minimize the uneven rubber thickness.