When most people think of milling machines, they envision a vertically oriented machine that contains rotary cutters. Traditional milling machines such as this are used extensively in the manufacturing industry to reshape workpieces. However, there are many other types of milling machines, one of which is a ball mill. What is a ball mill exactly, and how does it differ from traditional milling machines?
Overview of Ball Mills
Ball mills are a type of grinding machine that uses balls to grind and remove material. It consists of a hollow compartment that rotates along a horizontal or vertical axis. It’s called a “ball mill” because it’s literally filled with balls. Materials are added to the ball mill, at which point the balls knock around inside the mill.
How a Ball Mill Works
Ball mills work by using balls to grind materials. Materials such as iron ore, paint and ceramics are added to the ball mill. Next, the ball mill is activated so that it rotates — either on its vertical or horizontal axis. As the ball mill rotates, the balls bounce around while striking the enclosed material. The force of these strikes helps to grind the material into a finer, less-coarse medium.
For a ball mill to work, critical speed must be achieved. Critical speed refers to the speed at which the enclosed balls begin to rotate along the inner walls of the ball mill. If a ball mill fails to reach critical speed, the balls will remain stationary at the bottom where they have little or no impact on the material.
High Energy Ball Mill
A Ball Mill is a type grinder that blends or grinds materials for various applications. Impact force enables size reduction in feed material. The cylindrical shell rotates around its horizontal axis. The main element enabling grinding are the hard and small balls in the ball mill. These balls are usually made of steel. The inner surface of the hollow shell is coated with an abrasion resistant material. The balls are lifted up as the shell rotates and after an angle of 60° they drop down. This free falling movement create an impact where particles are reduced in size. Metal ores can be ground with ball grinder as well.
Planetary ball mills may be used for mixing, homogenizing, fine grinding, mechanical alloying, cell disruption, small volume high-tech material production, and even colloidal grinding. They are the ideal wet/dry milling tools for acquiring research samples with high efficiency and low noise. Vacuum jars may be used to process sample within a vacuum environment.