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Mechanical Finishing

Mechanical Finishing & Polishing

Mechanical polishing is the process of improving a metallic surface with pressurized contact and rotating friction of abrasive material. Mechanical polishing is also – not entirely accurately – known as grinding, buffing, or simply polishing.

Mechanical finishing of this kind can range from a rough grinding to eliminate metal burrs and level ridges on a metal surface, to a mirror-like polished shine. These ranged finishes are achieved through a variation of abrasive material, pressure applied while polishing, and time spent polishing. In this way, specific roughness values (Ra) can be accomplished.

Mechanical finishing, such as polishing, is a perfect solution for things like:

  • Stainless Steel Components
  • Pharmaceutical & Medical Equipment
  • Food & Beverage Applications

Mechanical Finishing Image Examples


In some cases components may need to undergo electropolishing services to achieve an overall acceptable roughness value.

While electropolishing service is often used as a final step, and increases an item’s corrosion resistance and brightness, it is not a substitute for mechanical polishing. Electropolishing cannot remove and smooth out imperfections such as:

  • Weld Seams
  • Orange Peel
  • Machine Tool Inclusion
  • Deep Pitting

The overall cost of mechanical polishing may also vary slightly due to major or numerous imperfections in the item to be finished. One should also keep in mind that the dimensions of the finished part may be decreased slightly in the process – though usually by very minute levels.

Mechanical Finishing | Bead Blasting

Another form of mechanical finishing is bead blasting, in which fine glass beads are applied to a component’s surface. The beads help to eradicate unwanted surface material and deposits that may not be easily removed by other finishing methods.

Bead blasting usually uses an air-powered pump to apply the glass beads at low pressure to reduce the risk of damage and the unwanted removal of surface area.

Central Electropolishing Co. uses an 11 x 11 x 20 ft. blasting cabinet, which enables our team to bead blast components of various sizes and for many applications.

Mechanical Finishing Designations

Central Electropolishing Co. uses a standardized mechanical finishing designation system for many of our components and clients. Though we are flexible enough to meet nearly any demand or specification, our most commonly used finish designations are:

  • Polished Finished No.3 – An intermediate polish generally used where a semi-polished surface is required for subsequent finishing operations following fabrication. It is also used as a final finish with a 50- or 80- grit abrasive compound.
  • Polished Finish No.4 – A general purpose, bright polished finish obtained with a 100-180 mesh abrasive which follows initial grinding with coarser abrasives.
  • Buffed Finish No.6 – A soft, satin finish having a lower reflectivity than the No.4 finish. It is produced with a greaseless compound; #200 grit top dressed with white rouge or chromium green rouge.
  • Buffed Finish No.7 – A highly reflective finished produced by buffing a surface that has been previously refined to a No.6 finish (approximately). The surface is then buffed lightly with a white rouge and does not remove the satin finish lines.
  • Buffed Finish No.8 – The most reflective finish that we commonly produce, the No.8 finish is obtained by flexible polishing with successively finer abrasive compounds. The surface is then buffed extensively with a very fine chromium green rouge bar compound.

You can read more about our finishing designations here.

Central Electropolishing Company’s Services

Central Electropolishing Services has a well-earned reputation for taking great care when applying any mechanical finishing processes to our customer’s components. Our dedicated machinists are trained to apply the perfect finishes without damaging parts, and our quality control specialists ensure that all parts meet your specifications for roughness and dimensions. Contact us today to learn more about our mechanical finishing services.