What are the types of gaps and stamping materials in mold injection molding?

Author: MULAN - Plastic Molding Manufacturer

Scrap is essentially the reverse image of a shape hole. That is, the same position in the opposite position. By checking the scrap, you can judge whether the gap between the upper and lower dies is correct.

If the gap is too large, the scrap will show a rough, undulating fractured surface and narrow bright banded areas. The larger the gap, the larger the angle formed by the fracture, and the larger the area of ​​the bright band. If the gap is too small, the scrap will show small angled fractured surfaces and wide bright banded areas.

Excessive gaps create holes with large curls and torn edges, making the silhouette stand out slightly with thin edges. A gap that is too small will produce ribbons that are slightly curled and torn at high angles, resulting in sections that are more or less perpendicular to the surface of the material. The ideal scrap should have a reasonable breaking angle and a uniform bright band.

This keeps punching pressure to a minimum and creates a clean round hole with minimal burrs. From this point of view, increasing the clearance to extend the life of the injection mold is at the expense of the quality of the finished hole. The choice of plastic mold clearance, the clearance of the mold is related to the type and thickness of the stamping material.

The unreasonable clearance will cause the following problems: (1) If the clearance is too large, the burrs of the parts to be stamped will be relatively large, and the stamping quality will be poor. If the gap is too small, although the punching quality is good, the stamping die will be severely worn, which will greatly reduce the service life of the die and easily cause the punch to break. (2) If the gap is too large or too small, it is easy to cause adhesion on the punching material, resulting in strips during the punching process.

If the gap is too small, it is easy to form a vacuum between the bottom surface of the punch and the plate, and the scrap will rebound. (3) Reasonable clearance can prolong the service life of the mold, has a good discharge effect, reduces burrs and flanging, keeps the board clean, the hole diameter will not scratch the board, reduces the number of sharpening times, keeps the board straight, and Precise stamping positioning.