1. Can I send in parts for re-finishing?
We can and do re-finish parts, but there are reasons that this is not a good idea:
- It always involves more work than finishing the part, as the old coating has to be removed first, and the surface reworked.
- If the part has been used, the metal might be contaminated, such as oil, grease, and mineral deposits.
- These contaminants will adversely affect that finish. In PVD deposition, not only can they ruin the coating on the parts with the contaminants, but they can also ruin the coating on adjacent parts.
- Some finishes cannot be stripped without seriously damaging the parts. Again, this may not be known until it is too late.
- Re-finishing may require disassembling the parts and then reassembling them. If, for example, the parts are press-fit, this may not be possible.
- Some parts cannot be refinished.
2. Is there a minimum lot charge?
Yes. Our minimum lot charge is $150.
3. What is the difference between (electro)plating and PVD?
Plating is a wet chemical process that involves dipping the part in a heated chemical solution for a fixed time. AMP&P electroplates, wherein an electrical current is used to break down the chemicals on the part surface and produce an enhanced coating with better adhesion. PVD, or physical vapor deposition, on the other hand, is an entirely dry deposition process conducted in a vacuum chamber. In lieu of a liquid, the metal in the coating comes from a solid target. It is vaporized in the chamber (as per the name) and, with the assist of electric and magnetic fields, drawn to the part surface, where it reacts with nitrogen and/or other reactive gases to form a coating that is at least twice as hard as the hardest plating, with better adhesion and wear resistance.
4. What’s the difference between hexavalent chromium and trivalent chromium?
Hexavalent and trivalent are terms relating to the number of oxidation state of chromium metal. Hexavalent chromium forms chemical compounds with an oxidation state of six (hexa is a prefix for six), while trivalent chromium forms chemical compounds with an oxidation state of three. In electroplating, depending on the bath, either form can be created, leading to formation of hexavalent chromium oxide, a compound consisting of one chromium atom and three oxygen atoms, or trivalent chromium oxide, a compound consisting of two chromium atoms and three oxygen atoms, a much larger molecule. The size difference is significant. Trivalent chromium oxide molecules are too large to get through cell walls, so do not represent a significant health hazard. The smaller hexavalent chromium oxide molecules, on the other hand, can penetrate cell walls, where they cause enough damage that the chemical is considered a class one carcinogen. For this reason, AMP&P refuses to work with hexavalent chromium, even though we have a zero-emission plating system.
5. What is meant by a “satin” finish?
A satin finish is meant to have a texture much like, well, satin cloth, hence the name. It entails grinding light lines in the metal surface. For some parts, this is a relatively easy process. For others, it is not. The surface has to be readily accessible, without any abrupt projections. When done the right way, and at AMP&P we always to it the right way, it is a very desirable appearance.