History From a revolutionary idea proposed and developed by Dr. Andrew Szegvari in 1945, Attritor technology grew to become the basis for Union Process, Inc., an independent, family-owned American company founded in Akron, Ohio. Today, Attritors are considered to be the most efficient grinding/dispersing systems and are used in scores of industries and research laboratories worldwide. More recently, Union Process has developed Attritors specifically designed for the dry grinding process. Continuous or Batch Operation SD Series The SD Dry Grinding Attritors can be operated in both continuous and batch processing applications. In the continuous operation, the material is fed into the vessel at the top. It then migrates through the agitating media bed where it is processed to a desired particle size and is discharged through metering bar grids at the bottom of the tank. In the batch mode, material is charged into the mill at the top, ground for a predetermined time, then discharged through grids at the bottom. The system can easily be sealed for grinding under inert gases such as nitrogen or argon. The SD Attritor is also used to make dispersion- strengthened metal (DSM). In this process (known as mechanical alloying or cold welding), the kinematic porosity results in the grinding media breaking the metals into small particles and beating them together to form agglomerates. By repeating the process, the various metals are evenly mixed and dispersed to form a new composition of alloy (DSM). HSA Series The HSA High Speed Attritor is generally used in a continuous mode. The material is charged into the mill at the top and is discharged out the bottom side, making use of centrifugal force. The HSA is used when smaller particle size (generally 40 mesh) materials are fed into the machine and micron size end product is desired. Also, it is often used for fibrous and polymer types of materials. Dry Grinding Attritors SD, HSA, and Lab Series The Dry Grinding Process The Attritor dry grinding process is achieved in a stationary tank by means of a rotating shaft and arms that agitate the media into a random state of motion of internal porosity called kinematic porosity. In this expanded condition, the media and particles are free to move, collide and impinge upon each other. KINEMATIC POROSITY EXPANDED MEDIA MEDIA AT REST EXPANDED MEDIA Revolving arm hits grinding media Media moves forward rapidly Media collides with media, breaking up product particle Stationary Shaft Rotating Shaft 2