The common problems with injection moulds

The injection mold is a tool for producing plastic products.It is also a tool to give plastic products complete structure and precise size.The structural form of injection mould and the quality of mould processing directly affect the quality and production efficiency of plastic products.The most common causes and troubleshooting methods of injection mold production and plastic products production are detailed as follows:

1.The gate stripping is difficult

In the process of injection molding, the gate is stuck in the gate sleeve, not easy to come out. When the mold is made, the product appears crack damage. In addition, the operator must use the tip of the copper rod to knock out from the nozzle, making it loose before stripping, which seriously affects the production efficiency. The main reason for this failure is the poor finish of the sprue cone hole and the circular direction of the inner hole with a knife mark. Secondly, the material is too soft, the small end of the cone hole is deformed or damaged after being used for a period of time, and the spherical arc of the nozzle is too small, resulting in the production of the rivet head of the gate material at this point. The taper hole of gate sleeve is more difficult to process, should adopt standard part as far as possible, if need to process by oneself, also should make oneself or buy special reamer. Taper holes shall be ground to above Ra0.4.In addition, the sprue drawing rod or sprue ejection mechanism must be installed.

2.The  leader pin is damaged

The leader pinmainly plays a guiding role in the mold to ensure that the molding surface of the mold core and the mold cavity do not touch each other under any circumstances. In the following cases, the fixed mold will produce a huge lateral migration force during injection :(1). When the wall thickness of the plastic parts is not uniform, the material flow rate is large at the thick wall, and a large pressure is generated here;(2). The plastic parts side asymmetry, such as the two opposite sides of the mold of the echelon parting face are not equal to the back pressure.

3.The movable platen appears bending

The mold makers sometimes do not pay attention to this problem and often change the original design size, or the movable platen with low strength steel plate instead, in the mold with the rod top material, because the two sides of the seat span is large, resulting in the injection template bending. Therefore, the moving template must be selected high quality steel, to have enough thickness, must not use A3 and other low strength steel plate, when necessary, should be set in the lower part of the moving template support column or support block, in order to reduce the thickness of the template, improve the bearing capacity.

4.The poor cooling or water leakage

The die cooling effect directly affects the quality and production efficiency of products, such as poor cooling, product shrinkage, or uneven shrinkage and warped surface deformation defects. On the other hand, the whole mold or local overheating, so that the mold can not form normally and stop production, serious so that the rod and other moving parts of the hot expansion and damage. The design of the cooling system, processing to the product shape, do not because the mold structure is complex or processing difficulties and omit this system, especially large and medium-sized mold must fully consider the cooling problem.

 


Post time: Apr-17-2020
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