​Sphere. Circle. Cylinder. Spin. Rotation. What do all of these words have in common? They are all moving around and/or are round, in some fashion. They are also related to mechanical milling. Here is how each of those words relates to this process and how their connections explain milling in the simplest of terms. 

The Spheres

​In mechanical milling there are dozens to hundreds of spheres made up of many different materials. Depending on what has to be beaten, ground, pulverized, etc. in the milling machine, different spheres in shape, size, number, and material type are added right before the milling begins. For example, say that you want to pulverize dried corn into corn flour. You would empty the milling machine, add dozens of metal spheres of a particular size to the machine, and then add your dried corn before shutting the door and flipping the on-switch. Different-sized spheres produce granules of different sizes, so the miller has to choose the correct size of milling sphere to get the right size granules of corn flour. In other milled products, the miller might use plastic, glass, ceramic, carbide, aluminum, etc., as the milling sphere material. 

Circles and Cylinders

​Milling spheres are circles, or at least circular. The milling machine is two cylinders, one cylinder inside the other. Cylinders also have a circular shape in that they are round on both ends and through the middle. It is this circular/cylindrical shape of the machine itself, and the spinning and rotation action (again, in a circle!), that causes the milling spheres to whip around inside and grind the material. There is no way that the milling process would work if the spheres were tossed about inside a square or cube shape machine, nor would such a machine spin and rotate effectively. 

​Spin and Rotation

The inner cylinder in a milling machine spins very rapidly. It has to, since the spinning and speed at which it spins is what provides the machine with the necessary centrifugal force to rotate the milling spheres against the substance that is to be ground or pulverized. The outer cylinder, or hull​, of the machine remains completely motionless, except for a steady shaking and rumbling of the interior cylinder in rotation. Unless the miller has to stop the machine very early or very quickly, the inner rotation continues until all of the material is fully ground into the desired form.

For more information, reach out to companies that supply mechanical milling equipment.

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