Grinders and grinding machines use an abrasive that is bonded to a wheel, belt or disc to remove material and improve surface finish. Devices can be pneumatically driven or powered by a combustion engine or electric motor. Grinders and grinding machines can use single-phase or three-phase power and are available in a range of voltages. 60 Hz power is used in North America. 50 Hz power is used internationally. Some devices require manual loading, setup, and operation. Others load parts automatically, include computer numerical control (CNC) machine tools and a programmable logic controller (PLC), or can be programmed or controlled through a personal computer (PC) interface. Bench mounted, floor mounted, stationary, handheld, and portable grinders and grinding machines are commonly available. Devices can also be mounted on tool posts, machines, or robotic arms.
There are many types of grinders and grinding machines. Angled grinders are suitable for manual tasks such as finishing, deburring, patterning, cutting, and polishing. Belt grinders and sanders consist of a driven contact wheel and a tensioning idler wheel or pulley. Grinding wheels are designed to hold bonded abrasives and provide greater rigidity or stiffness than equipment that is designed for flexible coated abrasives. Profile, form, gear and other processes shape the grinding wheel with a dressing to create a specific profile. Edge sanders and platen grinders consist of a driven contact wheel, a tensioning wheel or pulley, and an intermediate platen behind an abrasive belt. Backstand or benchstand grinders and polishers are suitable for offhand grinding or finishing. Surface, thread, and precision grinders; crankshaft, centerless, and creep feed machines; and cylindrical or internal devices are also available. Some grinders and grinding machines finish the inner diameter (ID) of a part. Others grind between the centers or between a chuck and a center.
Important specifications for grinders and grinding machines include rotary speed, surface or linear speed, power, and current. Optional features include cabinets and enclosures, double-sided disks, dressing systems, and dust collection or filtration systems. Devices with multiple heads can be used to carry abrasive products with a range of grit sizes. Some grinders and grinding machines use an orbital or planetary motion. Others use a vibratory or oscillatory motion. In some devices, motor speed can be adjusted continuously or set at discrete speeds within an operating range.
There are a variety of applications for grinders and grinding machines. Some devices are designed for woodworking or metalworking. Others are suitable for automotive applications such as part grinding and paint sanding. Grinders and grinding machines are used in the manufacture of medical devices, ceramics, glass, plastics, composites, semiconductors, and electronics. They are also used in cleaning and surface preparation, deburring and deflashing, tool and die sharpening, construction, and maintenance and repair (MRO) operations. Honing, lapping, and superfinishing equipment such as wafer planarization and chemical-mechanical polishing (CMP) machines are specialized devices that provide very flat, smooth, or low roughness average (RA) surface finishes. Very rigid machines make better use of abrasives in precision grinding applications.
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