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Coating to stop erosion of mold texture

Q. I am currently using a filled plastic resin fro injection molding that is eroding the texture on our tooling. Can you suggest a finish or coating that will help to increase the life of the texturing? Thanks.

Jill Miller
Engineering plastics - Chicago, Illinois , USA

A. That would depend on what you are currently using for your molds and what they might be currently coated with. Intricate patterns and depth of tiny areas will also make a difference.

James Watts
- Navarre, Florida

simultaneous replies

Hard chrome will likely stop your problem if due to mechanical wear. If due to chemical attack (molding PVC), then electroless nickel is a better solution.

jeffrey holmes
Jeffrey Holmes, CEF
Spartanburg, South Carolina


Electroless nickel coatings are commonly used to protect textured molds. Because of its uniformity, the coating can be applied after texturing. It will replicate the surface. The coating has a microhardness of about 500 HV, which will withstand quite a lot of wear.

Ron Duncan
Ron Duncan [deceased]
- LaVergne, Tennessee
It is our sad duty to note Ron's passing on Dec. 15, 2006. A brief obituary opens Episode 13 of our Podcast.

A. Either chrome or electroless nickel could protect your mold texture. We do both coatings and textures too. Now, to decide which one to apply, several things must be considered: 1-mold base material (some mold steels like H-13, S-7 and the like tend to accept chrome better), 2-mold size (large molds are risky to heat treat, so untreated EN is limited in hardness and chrome has the advantage for it comes out fully hard at 70Rc), 3-mold geometry or shape and depth of texture (deep patterns, cavities, sharp internal angles and ribs will not be properly coated by chrome, so EN will be a better choice). Finally, in our experience, the coating has to be easy to strip and re-coat in case of mold repair or engineering changes. We've seen dismal failures of Titanium nitrided molds due to this.

Guillermo Marrufo
Monterrey, NL, Mexico

A. Contact Bales Metal Surface Solutions [a supporting advertiser], Downers Grove, IL. They do work for us in terms of coating rolls and tools to protect the textures we apply.

Pete Kambouris
- New Berlin, Wisconsin

Ed. note June 2020: The internet changed enormously since 2004, with time proving that we must no longer post suggestions of brands or sources (why?). However, since Bales Metal Surface Solutions is a supporting advertiser, consider this a paid advertisement.

A. Chrome Nitride (CrN) by PVD can be a good choice depending on the geometry of the mold. The hardness is usually twice that of electrodeposited chrome, and the fine grain structure of the CrN wears very well against glass filled materials. There are also variations of CrN that can be tried as well.

Joe Kubinski
- Woonsocket, Rhode Island, USA

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