Finishing Operations in Metalworking

Finishing Operations

• Finishing operations can modify the surface of metals for a variety of reasons
• The purpose may be to enhance surface properties, achieve desired aesthetics, or apply decorative elements.
• These operations include surface preparation through cleaning and contaminant removal, as well as applying coatings like paints and platings.

Mechanical Cleaning

• Mechanical cleaning relies on physical methods to remove surface contaminants.
• Common contaminants include:
  • Sand from molds and cores used in casting
  • Scale from hot-working processes
  • Oxides like rust

Types of Mechanical Cleaning

• Blast cleaning
  • Uses an abrasive propelled against the surface using air, water, or a wheel.
  • Abrasives include steel grit, metal shot, glass shot, plastic beads, and CO2.
• Barrel finishing or tumbling
  • Used for finishing large quantities of small parts.
  • Parts are loaded into a barrel; additional media, such as metal slugs or abrasives (sand, granite chips, slag, or ceramic pellets), are added.
• Vibratory finishing
  • Versatile for deburring, radiusing, descaling, burnishing, cleaning, brightening, and fine finishing.
  • Performed in open containers.
  • Workpieces and media are loaded into tubs or bowls and vibrated at frequencies ranging from 900 to 3600 cycles per minute.
• Belt sanding
  • Uses a rotating abrasive belt that is driven by a motor.
  • The belt can be made of paper, cloth, or other materials with varying grit sizes.
  • Used for removing material, smoothing surfaces, and creating desired contours.
• Wire brushing
  • Uses rotating wire brushes to remove oxides, rust, and other surface contaminants.
  • Wires are made from different materials, including steel, brass, and nylon, based on the application.
• Buffing
  • Employs rotating wheels covered with cloth or felt.
  • Also uses a buffing compound containing abrasives to polish and shine surfaces, creating a smooth finish.
• Electropolishing
  • Electrochemical process that uses an electric current to remove metal from the surface.
  • Removes burrs, improves smoothness, and enhances corrosion resistance.

Explore the various finishing operations used to modify the surface of metals through techniques such as mechanical cleaning and coating application. This quiz covers the types of mechanical cleaning methods and their purposes, alongside the importance of surface preparation in metalworking. Test your knowledge on this critical aspect of metal fabrication.