Grinding machines use friction, attrition, or compression to smooth out a metal product’s surface. There are several types of grinding machines designed to deliver different levels of finite smoothness. For example, a ball-grinding mill is an excellent fine grinder for cement products, but may not work for more extensive smoothing projects.
Most metal grinding machines consist of a substrate within a rotating drum. Rod mills are used to make metal rods, while semi-autogenous grinding (SAG) mills and autogenous grinding mills smooth copper, gold, platinum, and silver.
Vibratory finishing machines deburr products and remove sharp edges. They position material inside a drum filled with abrasive pellets and a substrate, then apply a tumbling vibration to create a uniform random texture. The machine’s cycle speed and magnitude of vibration are usually variable, allowing effective treatment for a range of small- to large-sized parts.
An essential part of the grinding process is choosing the correct grinding media. This article will help you decide what type of grinding media is best for your application.
What to Consider When Choosing Grinding Media
Grinding media comprises a range of objects. Grinding balls, beads, satellites, cylinders, diagonals, and ball-cones are all different shapes of abrasives. The media itself can be made up of a variety of materials, such as carbon steel, stainless steel, chrome steel, and non-metallics like ceramics or steatite.
Selecting the right grinding media for your application depends on some interrelated factors.
The initial feed size matters because smaller media cannot easily break up large particles, so it shouldn’t be used for large particle applications. Similarly, the final particle size should be considered, as smaller media is more efficient when ultrafine particles are anticipated.
In general, high-density media give better results. The media should be denser than the material that is being ground. Also, highly viscous materials need media with a higher density to prevent floating. The specific gravity of grinding media is therefore essential to consider.
The harder the media, the higher the grinding competence and the longer the wear. Some of the harder grinding medias are made of hardened steel, tungsten carbide, agate, and zirconia. The overall abrasiveness should also be taken into account. If a highly-abrasive media is put into a grinding chamber that isn’t equally abrasive, not only will the media not be adequately ground, there is a risk of lasting damage to the chamber.