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  for Metal Finishing since 1989
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Fine Scratches and drag mark on my Gloss ABS product

2005

Hi, any opinion and suggestion what should I do for my case?

Right now I having a problem on my goods. I am try to produce HIGH GLOSS ABS. My mould is a mirror finish mould. Material we use is HIGH GLOSS ABS brand Toray 700 from Japan.
Problems occur where all my goods have fine scratches (all around and same spot), drag mark. Injection machine is 350 tonnage. The mould has a lot of pin holes on the mirror finish surface might be due to hand polishing. Any suggestion. Is it due to my mould condition (where the mis-process during the hard chrome or ..) or resin/material selection or machine injection properties.

AD lim
Employee - Ames, IA, USA

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2005

Consider electroless nickel plating the mold cavity; then polish the EN plating.
Pin holes are most often present in the basis metal. careful cleaning, and rinsing in alternate hot and cold water is necessary to remove cleaning solution form pin holes. Use about 6 oz/gallon sulfamic acid ⇦this on eBay or Amazon [affil links] for the acid dip after the hot/cold back and forth rinsing, then repeat the rinsing in a separate rinse system, then electroless nickel plate and polish.

Don Baudrand
Consultant - Poulsbo, Washington
(Don is co-author of "Plating on Plastics" [on Amazon or AbeBooks affil links]
           and "Plating ABS Plastics" [on Amazon or eBay or AbeBooks affil links])

I will always agree to the previous response because that's one of our specialties. But I think it would be better for you to identify the problem first rather than sorting it out. Normally parts molded in pitted cavities will replicate its surface. In other words, pits will become raised bumps, not scratches. Sometimes, depending on your process parameters, during the flow of the resin, superficial defects are formed that tend to elongate leaving welded lines that resemble scratches. In this case the lines will be aligned to the resin flow direction.

Guillermo Marrufo
Monterrey, NL, Mexico
2005