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Chapter 34

Chapter 34. Processes Used to Finish Metallic Materials. Objectives. Detergent washing to apply decorative or protective finish Removing burrs prior to finishing Electroplating protective metallic coating. Painting for finishing metallic parts. Washing systems.

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Chapter 34

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  1. Chapter 34 Processes Used to Finish Metallic Materials

  2. Objectives • Detergent washing to apply decorative or protective finish • Removing burrs prior to finishing • Electroplating protective metallic coating. • Painting for finishing metallic parts

  3. Washing systems • Cleaning is frequently carried out by washing the part in a detergent and in some cases a solvent degreaser. • Once the parts have been cleaned, they are rinsed thoroughly and dried. • Ferrous materials require rust inhibitors to prevent the newly cleaned parts from tarnishing. • Machined parts may require abrasive cleaning, tumbling, blasting, or brushing. • Companies are responsible for trapping and properly disposing off contaminates that are removed from the parts.

  4. Deburring • Burrs are sharp edges that are produced when metal is deformed by shearing, trimming, stamping, or machining. • Deburring is the process of removing burrs by filing, wire brushing, polishing, or abrasive machining. • Abrasives: Some abrasives are used for mechanical hand polishing while others are used with hand grinders to clean up welds and castings.

  5. Finishing Processes • Electroplating: careful cleaning and surface preparation of the work piece is critical to successful plating. • Common coating materials are chromium, copper, nickel, zinc, and tin. • In electroplating the work piece serves as the cathode. • The material that will plate the work piece makes up the anode.

  6. Finishing Processes • Anodizing: Anodizing is a electrochemical process that turns the surface of the work piece resistant to corrosion. • The aircraft industry is a major user of anodized parts. • Typical anodized products include aluminum utensils, furniture, automobile trims, and keys.

  7. Finishing Processes • Metallizing: Metallizing is the process of spraying or vacuum impregnating metallic coatings on metals and non metals. • Metallizing can be used on paper, wood, plastics, and metals. • Before the base material can be coated, it is necessary to roughen and clean the spray surface. This produces a better bond.

  8. Finishing Processes • Powder Coating: Normally the part is heated, the powder is applied, and additional heat is supplied to melt the powder, fusing it into a seamless coating on the surface of the metal. • Spray painting: Speed and finish quality made spray painting one of the most widely used processes in manufacturing. • Electrostatic paint systems: The spray gun charges atomized paint particles so that they are attracted to the grounded work piece. This minimizes overspray.

  9. Finishing Processes • HVLP (High volume low pressure) paint systems: HPLV spray systems deliver paint at 10 psi or less with transfer efficiency of 65 to 85 percent. • Electro coating: E-coating is used mostly in the automotive industry for body, suspension and brake components that need to be protected from corrosion but do not require a cosmetic finish. • It uses an electric current to deposit paint on the part.

  10. Summary • Machined parts may require abrasive cleaning, tumbling, blasting, or brushing. • Companies are responsible for trapping and properly disposing off contaminates that are removed from the parts. • Burrs are sharp edges that are produced when metal is deformed by shearing, trimming, stamping, or machining. • Deburring is the process of removing burrs by filing, wire brushing, polishing, or abrasive machining. • Electroplating: careful cleaning and surface preparation of the work piece is critical to successful plating. Common coating materials are chromium, copper, nickel, zinc, and tin. • Anodizing: Anodizing is a electrochemical process that turns the surface of the work piece resistant to corrosion.

  11. Home Work • 1. What are burrs? • 2. What is the advantage of anodizing?

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