centreless grinding is defined as the machining process in which materials are removed from a workpiece with the help of the abrasive cutting method. This is the exact opposite of centered grinding processes wherein the workpiece is secured and located using a fixture or a spindle. Basically, machineries offering centreless grinding has a work rest on which the workpiece is placed. On both the sides of this work rest would be the rotary grinding wheels, while one is a grinding wheel, the other is a regulating wheel.The regulating wheel is usually made out of soft materials like rubber with hard grain materials added in order to facilitate a decent traction between itself and the workpiece.
The speed of the rotation of these two wheels (relative to one another) can be adjusted depending upon the rate at which the material is required to be removed or shaved off from the workpiece. In case of this kind of machine, the workpiece is not mechanically constrained during the grinding process. Therefore, the grinder does not need workhead fixtures, drivers or center holes, this explains how the term 'centreless grinding' originated. High-tech or modern machines also offer computer numerical control feature in order to facilitate automation and improve precision of the end results.
Machines used for centreless grinding are usually employed in manufacturing units or factories wherein a large quantity of parts have to be processed within a short span of time. These machines are capable of providing grinding diameters of varying measurements, from something as small as 0.1 mm to as large as 125 mm. Thus, these machineries are suitable for processing workpieces or parts with high precision demands. Some of these also come with suction systems and can be used in conjunction with sanding sheets in the end for a smoother finish!
Now, centreless grinding machines are proper commercial machines, therefore on an average they weigh about 5 tons and are also on the expensive side of the price spectrum. Individuals who find it difficult to shell out a lump sum for investing in these kind of machinery can opt for used or second hand machine. You just need to ensure that they are in good condition before taking them under your wing!
A useful tip to keep in mind here would be to select machines which are in compliance with the set industry norms and guidelines. Sophisticated machineries would offer the microfeed-fine adjustment feature with the help of which one can adjust the depth of the cut. Some machines serve a dual purpose, i.e. they offer through-feed and in-feed centreless grinding. Depending upon what your preferences are and the type of products you need to manufacture you can go about taking your pick from these myriad options.
You can also purchase different types of grinding wheels and interchange them in order to produce different types of grits and shapes of the workpiece. Make sure you conduct your research well before purchasing this type of machinery because it is a big investment.