• 2023-08-28
• 575
• 5 Comments

Standard for mirror polishing of die molding

Standard for mirror polishing of die molding -- die molding polishing method and precautions

Polishing is a very important process in the process of making plastic molds. It is generally the process of polishing the surface of the mold cavity by using a whetstone, sandpaper, polishing paste, etc., so that the working surface of the mold can be bright as a mirror.

Mold polishing can make the surface of the product smooth and beautiful, in addition, it can make the product easier to release on the mold.

Mold mirror polishing processing standards are divided into four levels:

A0 = Ra0.008 microns

A1 = Ra0.016 microns

A3 = Ra0.032 microns

A4 = Ra0.063 microns

1. Method of mold polishing

die molding polishing, do not use the most fine stone, sandpaper, grinding and polishing paste at the beginning, that is not to throw off the rough lines, so the polished surface looks very bright, but a side light, the rough lines appear. Therefore, it is necessary to first polish from a coarse whitetstone, sandpaper or abrasive polishing paste, then change to a finer whitetstone, sandpaper or abrasive polishing paste for polishing, and finally polish with the finest abrasive polishing paste.

This looks like more trouble, more procedures. In fact, it is not slow, one process after another, the front rough processing lines are polished off, and then the following process, no rework, a walk down can make the mold finish meet the requirements.

Generally, the surface of the machined mold cavity is roughed with a coarse whetstone first, and the cut marks of the machine and tool are polished away, and then the coarse whetstone is polished to reach the marks, and then the surface of the fine whetstone is polished with fine sandpaper, and finally the surface of the mold cavity is polished with polishing paste or grinding paste. Finally, the effect is as bright as a mirror. This is the general process of polishing the mold.

Of course, if possible, you can use the ultrasonic polishing machine to polish the mold, which is more efficient and less laborious.

2. Polishing with sandpaper should pay attention to the following points

(1) Polishing with sandpaper requires the use of soft wooden or bamboo sticks. When polishing a round or spherical surface, the use of cork rod can better match the curvature of the round surface and the spherical surface. The harder wood strips, like cherry wood, are more suitable for polishing the flat surface. Trim the end of the strip to keep it in line with the surface shape of the steel, which can avoid deep scratches caused by sharp angles of the strip (or bamboo strip) touching the steel surface.

(2) When changing to different types of sandpaper, the polishing direction should be changed by 45°-90°, so that the stripe shadow left after polishing of the previous type of sandpaper can be distinguished. Before changing different types of sandpaper, the polished surface must be carefully wiped with a cleaning liquid such as 100% pure cotton dipped in alcohol, because a small gravel left on the surface will destroy the entire polishing work. This cleaning process is equally important when switching from sandpaper polishing to diamond abrasive paste polishing. All particles and kerosene must be completely cleaned before polishing can proceed.

(3) In order to avoid chafing and burning the surface of the workpiece, special care must be taken when polishing with #1200 and #1500 sandpaper. It is therefore necessary to load a light load and to polish the surface using a two-step polishing method. When polishing with each type of sandpaper, it should be polished twice in two different directions, turning 45°-90° each time between the two directions.