A grinding machine is a machine tool equipped with an abrasive wheel used for producing fine finishes or making light cuts on metals and other materials. There are various types of grinding machines. Their wheels, which differ in size and grain, are made up of a variety of stones, diamonds, and other inorganic materials. These machines are useful for roughing and finishing operations on tools and other equipment.
The grinding machine consists of a power-driven grinding wheel and a bed with a fixture to guide and hold the workpiece. The wheel is made to spin at the desired speed, based on the wheel’s diameter and manufacturer’s rating, usually by a formula. The grinding head can be controlled to travel across a fixed workpiece, or the workpiece can be moved whilst the grinding head stays in a fixed position. Very fine control of the grinding head or table position is feasible using a vernier calibrated hand wheel, or using the features of numerical control (NC) or computer numerical control (CNC).
Grinding machines remove material from the workpiece by abrasion, which can generate substantial amounts of heat. They therefore incorporate a coolant to cool the workpiece so that it does not overheat and exceed its tolerance range. The coolant also benefits the machinist, as the heat generated may cause burns in some cases. In very high-precision grinding machines (such as most cylindrical and surface grinders), the final grinding stages are usually set up to remove about 2/10000 millimeter (less than 1/100000 inch) of the workpiece surface per pass. This process generates such little heat that the temperature rise is negligible even without a coolant.
Types of grinders
There are various types of grinding machines. They include:
- Belt grinder: It is usually used as a way to process metals and other materials with the aid of coated abrasives. (Sanding is the machining of wood; grinding is the common name for machining metals.) Belt grinding is a versatile process suitable for all kind of applications, such as finishing, deburring, and stock removal.
- Bench grinder: This machine, secured to a workbench, usually has two wheels of different grain sizes for roughing and finishing operations. It is used for shaping tool bits or various tools that need to be made or repaired. Bench grinders are manually operated.
- Cylindrical grinder (including the centerless grinder): A cylindrical grinder may have multiple grinding wheels. The workpiece is rotated and fed past the wheel(s) to form a cylinder. It is used to make precision rods.
- Surface grinder (including the wash grinder): A surface grinder has a "head" that is lowered, and the workpiece is moved back and forth past the grinding wheel on a table that has a permanent magnet for use with magnetic stock. Surface grinders can be manually operated or have CNC controls.
- Tool and Cutter grinder, and the D-bit grinder: These machines usually perform the minor function of the drill bit grinder or other specialist toolroom grinding operations.
- Jig grinder: As the name implies, it has a variety of uses for finishing jigs, dies, and fixtures. Its primary function is in the realm of grinding holes and pins. It can also be used for complex surface grinding to finish work started on a mill.
- Altintas, Yusuf. 2000. Manufacturing Automation: Metal Cutting Mechanics, Machine Tool Vibrations, and CNC Design. Cambridge: Cambridge University Press. ISBN 0521659736.
- Krar, Stephen F. 1995. Grinding Technology. Albany: Delmar Publishers. ISBN 0827363907.
- Malkin, Stephen, and Changsheng Guo. 2007. Grinding Technology: The Way Things Can Work: Theory and Applications of Machining with Abrasives. 2nd ed. New York: Industrial Press. ISBN 978-0831132477.
- Repp, Victor E. 1999. Grinding technology. Fort Washington, MD: National Tooling and Machining Association. ISBN 0910399158.
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