Views:6 Author:Site Editor Publish Time: 2019-10-19 Origin:Site
Warpage and deformation of injection products are very difficult problems. It should be solved mainly from the aspect of die design, but the effect of adjusting forming conditions is very limited. The causes and solutions of warpage and deformation can refer to the following items:
1) When the residual stress caused by the forming conditions causes the deformation, the stress can be eliminated by reducing the injection pressure, increasing the mould temperature and increasing the resin temperature uniformly or by annealing.
2) Stress and deformation caused by poor demoulding can be solved by increasing the number or area of push rod and setting demoulding slope.
3) When the cooling method is not suitable and the cooling time is not uniform or insufficient, the cooling method can be adjusted and the cooling time can be prolonged. For example, the cooling circuit can be set as close as possible to the deformation.
4) For the deformation caused by forming shrinkage, it is necessary to modify the design of the die. Among them, the most important thing is to make the wall thickness of products consistent. Sometimes, in the case of necessity, we have to measure the deformation of the product, repair the die in the opposite direction and correct it. The resins with larger shrinkage are usually crystalline resins (such as polyformaldehyde, nylon, polypropylene, polyethylene and PET resins) which have larger deformation than non-crystalline resins (such as PMMA resins, polyvinyl chloride, polystyrene, ABS resins and AS resins). In addition, due to the fibre orientation of glass fiber reinforced resin, the deformation is also large.