1. Metal Finishing and Painting TSM 233 Unit 16

2. TSM 233 Metallurgy and Welding Processes Metal Finishing – No Applied Finish  No finish is applied as some metals do not corrode, or are allowed to corrode  Gold does not corrode (gets dirty)  Stainless steel, corrodes very slowly, will corrode more quickly if overheated, stressed.  Copper, does corrode to a green color, but is often allowed to corrode for its appearance.

3. TSM 233 Metallurgy and Welding Processes Metal Finish – Polishing and Sanding  Varying degrees of polish finishes.  Sanding, wire brushing, sandblasting, grinding.  Most metals will need to be protected from corrosion after polishing.  Can be coated with a wax, oil, polish, or clear spray.  Pork fat rules!! For coating cast iron skillets.

4. TSM 233 Metallurgy and Welding Processes Metal Finishing- Spray Painting  Most metals can be spray painted.  Surface needs to have some texture, light sanding.  Cleaned with solvent.  Use matched spray primer, required for new metal.  Spray paint coating, allow to dry (the paint solvent is allowed to evaporate).  Be careful with the type of paint. Paints from home improvement centers are ok, enamel and latex paints.  But some automotive paints and finishes are very toxic.  Finishes can be varied: smooth, textured, glossy, satin, dull.

5. TSM 233 Metallurgy and Welding Processes Metal Finishing- Powder Coating A combination of electrostatic plating and painting. A dry paint “plastic” dry powder is sprayed on the metal. The metal object is electrically charged, and the paint particles are opposite charged. The metal attracts the paint powder. The metal objects are baked in an oven. Produces a very durable paint finish.

6. TSM 233 Metallurgy and Welding Processes Metal Finishing- Plating  Metal type coating is applied as electrically charged particles.  Galvanized metal is an electro-plated zinc coating.  Tin plating is produced by electro-plating a thin coating of tin on the surface.  Chrome plating is another example.  Requires specialized equipment, to electrically charge the metal components.  Components are dipped or sprayed with the metal coatings.

7. TSM 233 Metallurgy and Welding Processes Metal Finishes - Anodizing  A dense oxide coating is produced on the metal surface.  Aluminum and titanium are often anodized.  Similar to electro-plating.  Use an acid solution, sulfuric acid is an example.  Color dyes are used to produce a variety of colored parts.