Surface Finishing

After machining, there are always some scratch marks left behind. These parts are polished to attain a certain look and feel, and this is called surface finishing.

From Wikipedia: Finishing processes may be employed to: improve appearance, adhesion or wettability, solderability, corrosion resistance, tarnish resistance, chemical resistance, wear resistance, hardness, modify electrical conductivity,

Types of finishing

Generallly, they are of two types:
1. Removing or reshaping
2. Adding or altering

Examples

They vary by the material in context (e.g. Textiles, Wood, Metal, Wood, Cement, Jewellery, etc.)

• Mirror Finish
• Shiny finish
• Matte Finish
• Coarsely Grained Finished
• Anti-microbial finish (Textiles)

Methods of finishing

• Sanding and Polishing
  • Can be done by hand, or by other techniques for hard to reach areas
• Electric Discharge Machine (EDM) Spark Erosion
  • Largely Replaced by Chemical Etching
• Media Blasting
  • Example: Silica, Glass, Aluminium Oxide, Dry Ice, Plastic Beads, etc.
• Chemical Etching
• Laser Etching

Some facts

• Material Removal is about 0.0003" - 0.0007" for most polishing applications after machining

Examples

Common Examples

Leather

Somehow shoe polish makes leather shoes shine, when applied with polish brush. The type of brush fibers also play a role.

Metal

In school we used to use Brasso for polishing school emblem and belt. Brasso is an inflammable material.

Industrial

Plastic

An example I saw on shorts:

This seems to be an example of shiny finish.

• Take the plastic trim, sand it in the sun
• Rub it with an 800 Wetordry paper
• Clean it up with alcohol wipes
• Prime it with a plastic primer (was Plastic Spray PS 12)
  • Add at least 3 coats of a normal primer
• When it is done, rub it with a 1500 wetordry paper
• Now apply the base coat, one that also contains a lacquer (was MOTIP Car Paint Acryl | Autolak / Autolack)
• When it is dry, again rub it with a 1500 wetordry paper
• Rub with a cretin compound (?) (was Menzerna MEDIUM CUT POLISH)
• After plenty of rubbing, it should start to look good
• Then add wax on to protect the painting (was Brillo Cera | Cera Briiho)