At the object level . Permissions allowed or denied at the object level apply to the entire object. For example, you can set an object-level permission on an OU object that allows a particular group, such as Account Operators, to create child objects in the OU. At the property level .
Ball mills are used in chemistry and in industry to grind hard solids to a very fine powder. They are very similar to rock tumblers. Basically, the idea is to rotate a container filled with heavy metal balls that crush the substance that you want to grind.
1 Grinding (abrasive cutting) , an abrasive machining process that uses a grinding wheel as the cutting tool. 2  Grinding machine, used in a machining operation to refine the surface of materials. 3  Angle grinder, a handheld power tool. 4  Coffee grinder, a machine used for grinding coffee.