Grinding media comprise a wide range of objects such as grinding balls, beads and satellites, as well as more rare shapes like cylinders, diagonals and balcones. The media itself can be composed of a variety of materials, including carbon steel, stainless steel, chrome steel and non-metallics like steatite or ceramics. Selecting the right grinding media for a specific application depends upon several factors, some of which are interrelated: INITIAL FEEDSIZE: Smaller media cannot easily break up large particles. FINAL PARTICLE SIZE: Smaller media are more efficient when ultrafine particles are desired. SPECIFIC GRAVITY: In general, high-density media give better results. The media should be more dense than the material to be ground. Also, highly viscous materials require media with a higher density to prevent floating. HARDNESS: The harder the media, the better the grinding efficiency and, consequently, the longer the wear. DISCOLORATION: Some media may cause light-colored slurry to turn gray. pH: Some strong acid or basic slurriesmay react with certainmetallicmedia. THROUGH-HARDENED CARBON STEEL BALLS TYPE 1065 Through-Hardened Carbon Steel Balls are magnetic and can be used in the food industry along with 440C stainless steel media. They are a low- cost media that are superior and recommended over case-hardened carbon steel media which have a soft core. They are packaged with no oil finish—always dry packed—as they will rust in water. CHROME STEEL BALLS TYPE 52100 Chrome Balls (steel type 52100) are through-hardened and tempered steel balls designed to achieve maximum strength and quality. Ball hardness is in the 60–67 HRC range. They wear better than 440C stainless steel and through-hardened carbon steel. They are also recommended for applications where a through-hardened steel ball is needed in larger sizes (½" and larger). They are sometimes packaged with a very light oil finish to reduce rust due to humidity. 440C STAINLESS STEEL BALLS 440C Stainless Steel Balls are through-hardened and tempered throughout for maximum strength and quality. They are magnetic, and corrosion-resistant (generally rust-resistant). They are recommended for food applications and lighter colored slurries. CARBON STEEL SHOT Carbon Steel Shot media is through-hardened and very lowcost. As such, they are not uniformly spherical and often can leave a gritty black residue. FORGED STEEL BALLS — LARGE DIAMETER Forged Steel Balls are used for gold mining, cement factories, oil processing and large scale industrial applications. They are made by machine (standard) sizes 20mm–75mm. They are manually made (hit by air hammer) sizes 75mm–125mm. They have hardness 55–63 HRC. All forged balls are through-hardened, and shipped in 55-gallon steel drums. They range in sizes from 20mm–125mm.Standard lead time is 6–8 weeks FOB Akron, Ohio USA. HIGH CHROME CAST STEEL BALLS High Chrome Steel Balls can be used for many different applications. They are available in two grades—10–13%chrome (surface hardness ≥ 60 HRC, core hardness ≥ 58 HRC), and 14–18%chrome (surface hardness ≥ 62 HRC, core hardness ≥ 60 HRC). They have a very rough black finishwhich quickly wears off during initial milling. After that, they have an excellent wear rate. They are available in sizes 6mm–120mm. They are shipped in 55-gallon steel drums with standard lead time of 6–8 weeks FOB Akron, Ohio USA. CONTAMINATION: Material resulting from the wear of the media may affect the product and may need to be removed by a magnetic separator, chemicals, or a sintering process. CONSISTENCY IN SIZE: Although more important with mini media, ideally onewants all the same size. In these small sizes, there are ranges because, duetothemanufacturingprocess,themediamustbeclassifiedorscreened. COSTS: Media that may be 2–3 timesmore expensivemay last considerably longer, and therefore, be well worth the extra cost over the long run. The type of mill also can affect the selection of grinding media. Ball Mills use very largemediawhile Attritors employ media ranging in size from 1 ⁄ 8 " to 3 ⁄ 8 ". Horizontal mills requiremuch smaller media, as small as 0.3mm to 2mm.