Analysis and solution of plastic mold forming flash
Analysis and solution of plastic mold forming flash is following:
The burrs of the product mostly occur on the split surface of the mold, that is, between the movable mold and the static mold, the sliding portion of the slider, the gap of the insert, the pore of the ejector rod, etc., and the excess burrs are formed on the workpiece. .
Such a flashing edge not only fails the product, but also easily causes local depression of the mold to form a vicious cycle in which the flash edge is increased. Therefore, if you first find that a flash has been produced, you must trim the mold as soon as possible.
There are several reasons for the production of burrs.
Insufficient clamping force
Compared with the projected area of the molded part, if the clamping force is small, a gap will occur between the moving and static modes due to the action of the injection pressure, so that flash burrs are bound to occur. In particular, when the side gate is placed on the hole near the center of the workpiece, since the molded gate requires a large injection pressure, burrs are highly likely to occur.
Reducing the injection pressure or increasing the clamping force can eliminate this kind of defect. If the plasticity is changed to low pressure molding according to the specific situation, it is sometimes very effective.
2. The mold is not tightly fitted
Firstly, the injection molding machine is not tightly clamped. Although the mold itself is tightly clamped, when the injection molding machine using the toggle-type clamping mechanism is formed, it is often caused by poor parallelism of the mold or poor adjustment of the clamping device. The phenomenon of unbalanced clamping on both sides, that is, only the left and right sides are locked, and the other sides are not closely attached. At this time, the tie rods (two or four pull tabs) must be adjusted to balance the mid-expansion.
Secondly, the mold itself is poorly assembled. Such as inserting through the wearing position, inserts, slanting tops, thimbles and cylinders, etc., the gap exceeds the overflow value of the plastic material, forming a flash.
In addition, it is a slanted top and a row position. Because they are motion mechanisms, they are often prone to burrs, so the coordination of the slanted top rows is important. It is necessary to ensure smooth operation and no flashing. It is recommended to machine the oil groove in place and ensure lubrication in place, or nitriding treatment.
3. Mold deformation caused
If the strength of the mold is not enough, the deformation will occur due to the injection pressure, and the burrs will be caused by the poor mold making. It can be improved by thickening the thickness of the stencil and increasing the reinforcing dies such as the struts.
4. Exhaust groove depth is not reasonable
5. Injecting too much melt
This is not the direct cause of the burrs. In order to prevent the shrinkage of the hole, it is wrong to inject too much melt, and it is necessary to increase the injection time or the holding time to form (refer to the shrinkage hole).
6. There are foreign objects on the mold surface
There are foreign objects on the mold clamping surface, which will inevitably produce burrs. To solve this problem, it is obvious that it should be cleaned on the surface of the net mold so that the mold surface can be closely attached.
These are analysis and solution of plastic mold forming flash,must be improved during the plastic mold and plastic injection molding process.