Page 68 - Injection Molding Advanced Troubleshooting Guide

6.2 Mold Polish 51

Note that as the polish of a mold becomes finer the cost increases significantly as
does the effort required to maintain the high polish. When dealing with diamond
polished surfaces contact with the mold surface and any foreign objects including
mold wipes should be minimized to avoid scratching the surface. If there is any
contamination on the mold wipe or the mold surface the chances of damaging the
diamond polished surface are very high. For lens molding often times the way to
clean a mold is spraying with a can of mold cleaner and blowing the mold cleaner
from the surface with an airline.
Maintenance of a diamond polished surface should be conducted by trained per-
sonnel who can determine the proper polishing media and techniques. Diamond
polishing may require wood or felt for application and the wrong choice of paste or
technique may cause substantial damage to the mold.
A draw polish is a polish method where the final step of polish is in the line of
draw. Using a draw polish will normally provide better release of a molded part.
There are many cases where a rougher draw polish provides a much better release
than a finer polish, so do not assume that polishing to a finer level will eliminate
sticking. Remember that even an A1 diamond polish has microscopic scratches
from the act of polishing, and these scratches may inhibit release of the part.

References
[1] First appeared in Plastics Technology Magazine 3/31/15 “Tooling: Clearing Up the Mysteries Of
Mold Texture”, Kerkstra, Randy