A centreless grinding process is an outside-diameter grinding process. The procedure entails removing material from components or items using abrasive cutting or grinding. It differs from centred grinding. In that, the material on which the work is being done is not held in place by a spindle. Instead, it’s held in place by a pair of rotating grinding wheels that spin at predetermined speeds.
A centreless grinding machine can achieve precision in cylindrical surfaces, roundness, and exceptional accuracy when processing high-volume automotive components and hydraulic and fluid control parts.
Fundamentals of centreless grinding
The centreless grinding process requires a thorough understanding of the fundamentals to get consistent and high quality outcomes. The workpiece is fastened between two grinding wheels in centreless grinding, wherein the rotatory grinding wheel’s speed is determined by the rate at which material is removed from the workpiece.
Compared to the workpiece, the grinding wheel rotates along a fixed axis and has a higher angular velocity. The regulating wheel just applies external pressure for correct grinding and provides linear feed to the workpiece. The grinding wheel is solely responsible for machining.
The regulating wheel is not fixed at its axis; it can move in order to maintain proper contact between the workpiece and the grinding wheel. The workpiece is positioned over a stationary work-rest plate. The grinding wheel coupled with the regulating wheel, is used to modify the workpiece’s position. Grinding wheel materials are mostly made from a solid steel or aluminium disc with particles bonded to the surface.
Grinding wheel consists of a composite material. Coarse particle presses and bonds together. This results in the formation of solid circular shape of the various types of grinding wheels. Grinding wheels are made up of abrasives that acts as a tooth in the saw. These grinding wheels act as a regulating agent controlling the material removal state, surface finishing, polishing and geometrical accuracy.
What are abrasive materials in grinding machines?
Abrasives are grain-like material substances used in the grinding wheels of the centerless grinding or any grinding machine for that matter. Each of these abrasive grains are bonded together into a cylindrical grinding shape.
Specifications of centreless grinding machines
Most of the centreless grinding machines feature hydrodynamic and anti-friction bearings equipped with grinding and regulating wheel spindles. They have centralised lubrication systems and pressure switches. A lubrication system lubricates continuously while the machine is working. It lubricates the workpiece while bearings are rotating and improves the distribution of lubricants. Whereas the pressure switch regulates the grinding wheel and regulating wheel spindles allowing only when oil enters into beanings thereby providing safety protection for the spindle bearings. Palmary centreless grinding machines are known for its accuracy and efficiency. They are equipped with CNC controls and operator friendly.
Types of centreless grinding
In-feed centreless grinding
When one part has a bigger section than another, in-feed centreless grinding, also known as plunge grinding, is utilised. With in-feed centreless grinding, you lay your part on the work rest and use the regulating wheel to feed it into the grinding wheel progressively. In-feed centreless grinding is frequently used to make complex pieces with different diameters. Small parts with tight tolerances benefit greatly from this type of grinding.
Through-feed grinding is the most common type of centreless grinding. Through-feed grinding is known for its productivity since it grinds from one side of the machine to the other without stopping. The workpiece is dragged between the grinding and regulating wheels, allowing for faster & efficient manufacturing. This method is used by grinding companies that create high-volume orders of components with minimal characteristics.
Applications of centreless grinding
Centreless grinding machines has a wide range of applications & techniques, just like other types of grinding. Few of them are -
When a large number of pieces must be processed in a short amount of time, centreless grinding is the best option
In the production of numerous high-volume automotive components, centreless grinding is essential
Centreless grinding is also used to make parts for the hydraulics and fluid control, medical, and aerospace industries
Centreless grinding is an exciting method that removes the right amount of materials precisely, to produce a perfectly finished workpiece. It’s a technology that’s used in a lot of manufacturing operations and it’s really efficient. Centreless grinding is a suitable choice for manufacturers who demand high volume production with rapid rounding and accuracy. It may be used to quickly and precisely make a wide range of parts.
Courtesy: Phillips Machine Tools India