Centerless Grinding Technology
Centerless grinder is a type of milling machine that utilizes an electric current to cut materials from a workpiece without cutting the material into the surface. This is different from the usual grinding where the workpiece is fed through a wheel and the grinding wheel passes over the work. This type of milling machine is similar to the grinder wheel used in grinding but with the current running through a larger area.
Centerless Grinder: The two wheels of the centerless grinder are the work wheel and the work surface. The work wheel contains a number of holes and the holes are lined up along the work piece while the work surface has a mandrel that fits into the holes and holds the work in place. When turning the rotary tool, the rotation of the spindle allows the abrasives to be deposited through the holes in the workpiece. The abrasives are then removed from the work piece by the in-feed grinding movement. These two grinding systems are commonly used together to produce a rough metallic finish.
Similar in concept to the centerless grinders are the radial grinders. These grinders do not have two wheels but a single, wide-spaced disc. The main advantage of using these types of grinders is their ability to quickly grind small irregular shaped parts. Unlike the centerless grinders, these machines use a direct current to operate. These machines are suitable to grind small items such as screws and bolts in small dimensions. Because they have no outer edges, they do not catch rust easily.
A number of designs were designed to improve the performance of these grinding machines. These improvements include increasing the cutting speed and reducing the wear on the motor, adjusting the workpiece to match the diameter of the grinding wheel, and developing a centerline that allows the workpiece to be gripped more precisely. The centerline permits the use of a fine and shallow cutting wheel with little restriction. The need for a fine cutting wheel is eliminated because the workpiece will be ground to the same diameter as the grinding wheel, resulting in increased accuracy and less chatter.
Another improvement found in centerless grinders involves the use of universal joints. Universal joints allow for the use of interchangeable parts in a variety of applications such as switching a centerline or adjusting workholding angles. The universal joints also provide for the transfer of data for multiple workholding components. The transfer of data is accomplished by utilizing a common carrier that carries both the data and the workpiece so that the change in one part does not affect the other parts. With this type of system the need for expensive and complex parts is eliminated, saving both time and money.
A new type of technology known as a computer numerical control (CNC) machines offer benefits to users when cutting edge work pieces. Using a CNC computer software, the operator can program the cutting movements of the CNC machine to create a succession of cutting actions to achieve precise machined ends. The program operates the CNC machinery while the operator works in a remote location and is not limited by mechanical problems or operator error. When CNC guided centerless grinders are used, they are able to create machined holes at rates much greater than those of the conventional milling machines, as well as, providing users greater accuracy with less operator intervention required.