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Tiny spots on surface of white gold

2003

Dear Sir, Greetings to you,

My Production is in 18 K white gold and casted on yasui VPC machine. After casting surface is quiet fine but when I start my pre-treatment for barreling, that constitutes magnetic polisher for 15 minutes in 0.2 mm needle and then to grinding with white plastic chips (polyurethane -medium cutter mixture of 50% each comprising of pyramids and cones of 10 mm) in centrifugal disc finisher from otec-germany. Now as per grinding time of 2.5 hrs, it is observed that tiny spots are visible on the surface which adds more of rework for bench person ahead. My observation states that it is due to magnetic polisher. I tried it the other way i.e. without magnetic polisher but still there are tiny spots but lesser in quantity than what we get with magnetic polisher. Kindly suggest us to improve our production.

Thanx,

Sayed Salim Ali
- Mumbai, India

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Difficult to determine problem based upon inf. #1 I'd first check purity of raw material and casting procedure. #2 I'd definitely do you plastic cut down process first. I'm not sure what plastic media you are using, but if you are getting the surface finish you require, I wouldn't worry about it. #3 All S.S. media in the magnetic system seem to leach out the carbon particles in the stainless; therefore, that would be the only other thing to look at. As an alternate polishing method, you might want to try using treated dry organic materials instead of the magnetic system.

AF Kenton
retired business owner - Hatboro, Pennsylvania
2003