Tube and Bar Grinding

Turned, Ground, and Polished (TGP) is a classification of finishing processes often used for metal shafting. Turning (on a lathe) creates straight round bars without the strain induced by cold drawing, while grinding and polishing improves the surface finish and roundness for high dimensional accuracy. Extreme straightness is critical in high-speed applications to prevent vibration and reduce wear on bearings.

Drawn, Ground, and Polished (DGP) is a classification of finishing processes often used for metal shafting. Cold drawing increases the metal’s strength, while grinding and polishing improves the surface finish and roundness for high dimensional accuracy.

Polishing & Buffing

Polishing and buffing are finishing processes for smoothing a work-piece’s surface using an abrasive and a work wheel or a leather strop. Technically polishing refers to processes that use an abrasive that is glued to the work wheel, while buffing uses a loose abrasive applied to the work wheel. Polishing is a more aggressive process while buffing is less harsh, which leads to a smoother, brighter finish. A common misconception is that a polished surface has a mirror bright finish, however most mirror bright finishes are actually buffed.

Polishing is often used to enhance the appearance of an item, prevent contamination of instruments, remove oxidation, create a reflective surface, or prevent corrosion in pipes. In metallography and metallurgy, polishing is used to create a flat, defect-free surface for examination of a metal’s micro-structure under a microscope. Silicon-based polishing pads or a diamond solution can be used in the polishing process. Polishing stainless steel can also increase the sanitary benefits of it.

The removal of oxidization (tarnish) from metal objects is accomplished using a metal polish or tarnish remover; this is also called polishing. To prevent further unwanted oxidization, polished metal surfaces may be coated with wax, oil, or lacquer. This is of particular concern for copper alloy products such as brass and bronze.

While used less extensively than traditional mechanical polishing, electropolishing is an alternative form of polishing that uses the principles of electrochemistry to remove microscopic layers of metal from a base surface. This method of polishing can be fine tuned to give a wide range of finishes, from matte to mirror-bright. Electropolishing also has an advantage over traditional manual polishing in that the finished product will not experience the compression and deformation traditionally associated with the polishing process.