The Purpose of Injection Mold Polishing-perfect plastic parts

2026,01,07

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Injection mold polishing has two purposes: one is to increase the surface finish of the mold, resulting in a smooth, beautiful, and aesthetically pleasing surface on the molded product; the other is to facilitate easy demolding, preventing the plastic from sticking to the mold and making it difficult to remove.

The following points should be noted during injection mold polishing:

(1) When a new mold cavity begins processing, the workpiece surface should be inspected first. Clean the surface with kerosene to prevent dirt from adhering to the oilstone surface and causing it to lose its cutting function.

(2) When grinding rough textures, proceed from difficult to easy areas, especially difficult-to-reach corners and deep bottoms, which should be ground first.

(3) Some workpieces may be assembled from multiple pieces for polishing. First, grind the rough textures or spark marks on each individual workpiece, then assemble all the workpieces and grind them until smooth.

(4) For large flat or side surfaces, after grinding away the rough textures with an oilstone, use a straight steel plate for light transmission testing to check for unevenness or undercuts. Undercuts can lead to difficult demolding or damage to the molded part.

(5) To prevent undercuts on mold workpieces or to protect certain mating surfaces, use saw blades or sandpaper attached to the edges for ideal protection.

(6) When grinding flat surfaces of the mold, use a back-and-forth motion, keeping the handle of the oilstone as flat as possible, not exceeding 25°. Too much angle will cause the force to be directed downwards, easily resulting in many rough textures on the workpiece.

(7) If the flat surface of the workpiece is polished with sandpaper pressed by a copper or bamboo piece, the sandpaper should not be larger than the tool area; otherwise, it will grind areas that should not be ground.

(8) The shape of the grinding tool should closely match the surface shape of the mold to ensure that the workpiece is not deformed during grinding.

If the above points are followed, the polished injection mold will have a beautiful appearance.

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Author:

Mr. Kama Liu

E-mail:

sale@hwplasticparts.com

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+86 15069372818