A grinding machine, often shortened to grinder, is a machine tool

Machine tool

A machine tool is a machine, typically powered other than by human muscle , used to make manufactured parts in various ways that include cutting or certain other kinds of deformation...

 used for grinding

Grinding (abrasive cutting)

Grinding is an abrasive machining process that uses a grinding wheel as the cutting tool.A wide variety of machines are used for grinding:* Hand-cranked knife-sharpening stones * Handheld power tools such as angle grinders and die grinders...

, which is a type of machining

Machining

Conventional machining is a form of subtractive manufacturing, in which a collection of material-working processes utilizing power-driven machine tools, such as saws, lathes, milling machines, and drill presses, are used with a sharp cutting tool to physical remove material to achieve a desired...

 using an abrasive wheel

Grinding wheel

A grinding wheel is an expendable wheel that is composed of an abrasive compound used for various grinding and abrasive machining operations...

 as the cutting tool. Each grain of abrasive on the wheel's surface cuts a small chip

Swarf

Swarf, also known as turnings, chips, or filings, are shavings and chippings of metal — the debris or waste resulting from metalworking operations including milling and grinding. It can usually be recycled, and this is the preferred method of disposal due to the environmental concerns regarding...

 from the workpiece via shear deformation.

Grinding is used to finish workpieces which must show high surface quality (e.g., low surface roughness) and high accuracy of shape and dimension. As the accuracy in dimensions in grinding is on the order of 0.000025mm, in most applications it tends to be a finishing operation and removes comparatively little metal, about 0.25 to 0.50mm depth. However, there are some roughing applications in which grinding removals high volumes of metal quite rapidly. Thus grinding is a diverse field.

Introduction

The grinding machine consists of a power driven grinding wheel spinning at the required speed (which is determined by the wheel’s diameter and manufacturer’s rating, usually by a formula) and a bed with a fixture to guide and hold the work-piece. The grinding head can be controlled to travel across a fixed work piece or the workpiece can be moved whilst the grind head stays in a fixed position. Very fine control of the grinding head or tables position is possible using a vernier

Vernier scale

A vernier scale is an additional scale which allows a distance or angle measurement to be read more precisely than directly reading a uniformly-divided straight or circular measurement scale...

 calibrated hand wheel, or using the features of numerical control

Numerical control

Numerical control refers to the automation of machine tools that are operated by abstractly programmed commands encoded on a storage medium, as opposed to controlled manually via handwheels or levers, or mechanically automated via cams alone...

s.

Grinding machines remove material from the workpiece by abrasion, which can generate substantial amounts of heat; they therefore incorporate a coolant

Cutting fluid

Cutting fluid is a type of coolant and lubricant designed specifically for metalworking and machining processes. There are various kinds of cutting fluids, which include oils, oil-water emulsions, pastes, gels, aerosols , and air or other gases. They may be made from petroleum distillates, animal...

 to cool the workpiece so that it does not overheat and go outside its tolerance

Tolerance (engineering)

Engineering tolerance is the permissible limit or limits of variation in# a physical dimension,# a measured value or physical property of a material, manufactured object, system, or service,# other measured values ....

. The coolant also benefits the machinist as the heat generated may cause burns in some cases. In very high-precision grinding machines (most cylindrical and surface grinders) the final grinding stages are usually set up so that they remove about 200 nm (less than 1/100000 in) per pass - this generates so little heat that even with no coolant, the temperature rise is negligible.

Types

These machines include the:

• Belt grinder, which is usually used as a machining method 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
  Belt grinding
  Belt grinding is a machining method to process metals and other materials with the aid of coated abrasives.The basic difference between belt grinders and belt sanders is the material being machined. Sanding is the machining of wood, grinding is the common name for machining...
  
   is a versatile process suitable for all kind of applications like finishing, deburring, and stock removal
  Stock removal
  High stock removal is a technological process with the goal to remove large / substantial amounts of material. The quantity of material, which can be removed in a specific process, depends on the material properties and the machining tool used.-Materials:...
  
  .
• Bench grinder
  Bench grinder
  A bench grinder is a type of benchtop grinding machine used to drive abrasive wheels. A pedestal grinder is a larger version of a bench grinder that is mounted on a pedestal, which is bolted to the floor...
  
  , which usually has two wheels of different grain sizes for roughing and finishing operations and is secured to a workbench or floor stand. Its uses include shaping tool bits or various tools that need to be made or repaired. Bench grinders are manually operated.
• Cylindrical grinder
  Cylindrical grinder
  The cylindrical grinder is a type of grinding machine used to shape the outside of an object. The cylindrical grinder can work on a variety of shapes, however the object must have a central axis of rotation...
  
   which includes 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 which includes the wash grinder. A surface grinder has a "head" which 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
  Tool and Cutter grinder
  A tool and cutter grinder is used to sharpen milling cutters and tool bits along with a host of other cutting tools.It is an extremely versatile machine used to perform a variety of grinding operations: surface, cylindrical, or complex shapes...
  
   and the D-bit grinder. These usually can perform the minor function of the drill bit grinder, or other specialist toolroom
  Toolroom
  The term toolroom can refer to three related concepts. The concepts have evolved over the past two centuries as technology itself has evolved.- Storing tools :...
  
   grinding operations.
• Jig grinder
  Jig grinder
  A jig grinder is a machine tool used for grinding complex shapes and holes where the highest degrees of accuracy and finish are required.The jig grinder is very similar to a jig borer, in that the table positioning and spindles are very accurate...
  
  , which as the name implies, has a variety of uses when 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.
• Gear grinder, which is usually employed as the final machining process when manufacturing a high precision gear. The primary function of these machines is to remove the remaining few thousandths of an inch of material left by other manufacturing methods (such as gashing or hobbing).