Release time：2022-04-18
Most of the burrs on the plastic shell of the power supply occur on the parting surface, that is, where the molten material flows into the place between the moving mold and the static mold, the sliding part of the slider, the gap of the insert, the hole of the ejector rod, etc., and redundant flash burrs are formed on the plastic shell of the power supply.
This kind of flash and burr acts as a lever during forming, which will further increase the flash and burr, resulting in local depression of the mold, and the formation of flash and burr will enter the vicious circle of increase. Therefore, if the plastic shell of the power supply is found to have flash burrs at the beginning, the mold must be repaired as soon as possible.
Plastic shell of power supplyThere are several reasons for burrs:
1. Insufficient clamping force
Compared with the projected area of the plastic shell of the molding power supply, if the mold locking force is small, there will be a gap between the moving mold and the static mold due to the injection pressure, which will inevitably produce flash burrs. Especially when the side gate is placed on the hole near the center of the plastic shell of the power supply, because this molding gate requires a large injection pressure, it is prone to burrs.
Reducing the injection pressure or increasing the clamping force can eliminate this defect. Sometimes it is also very effective to use plastic raw materials with good fluidity for low-pressure molding according to the specific situation.
2. The mold part of the plastic shell of the power supply is not closely matched
First of all, we will discuss the problem of loose clamping between the moving mold and the static mold. Although the mold of the plastic shell of the power supply itself is tightly closed, when the injection machine adopts the elbow bar type mold locking mechanism for molding, the mold locking on the left and right sides is often uneven, that is, only one side of the left and right sides is locked, while the other side is not tightly attached, which is caused by the poor parallelism of the mold or the poor adjustment of the mold locking device, At this time, the pull rod (two or four pull rods) must be adjusted to expand evenly.
Secondly, there is the power supply plastic shell mold itself research and matching is not in place, resulting in poor sealing. Especially when there is a forming hole in the center of the plastic shell of the power supply, burrs are easy to appear when the clamping force is insufficient due to the support of this part.
In addition, it is a sliding core. Because the moving core is an action mechanism, burrs often occur, so the cooperation of sliding core is very important. In particular, the projection area of the side of the left and right split Haff mold is also affected by the forming pressure. If the design cannot fully withstand this pressure, burrs often appear. The clearance of the insert and the pores of the ejector rod will not only increase the vicious cycle of burrs, but also increase the ejection resistance.
3. Caused by mold deflection of plastic shell of power supply
If the power supply plastic shell mold is not original enough, it will be flexed by the injection pressure. At this time, if there is a hole near the center, burrs will appear around the hole; Burrs will also appear around the hole and sprue when the side gate is opened with the center hole. The burr caused by this reason is caused by poor mold making, which is difficult to repair. Burr can be reduced by strengthening the mold.
4. The fluidity of plastic is too good
It is only because the fluidity of plastic is too good that it is not the cause of burr in theory. But when the fluidity of plastic is too good, even tiny cracks can be drilled into plastic, so burrs are easy to appear. In order to eliminate such burrs, the melt temperature or injection pressure can be reduced, and the mold temperature or injection speed can also be reduced.
5. Too much molten material is injected
This is not the direct cause of burrs. In order to prevent shrinkage, it is wrong to inject too much molten material. It is necessary to increase the injection time or pressure holding time for molding.
6. There are foreign matters on the surface of the plastic shell mold of the power supply
There are foreign matters on the clamping surface of the mold, which will inevitably produce burrs. To solve this problem, it is obvious that the clean mold surface should be cleaned to make the clamping surface close.
