Anangle grinder, also known as aside grinder ordisc grinder, is a handheldpower tool used forgrinding (abrasive cutting) andpolishing.
The high-speed angle grinder was invented in 1954[1] by German company Ackermann + Schmitt (FLEX-Elektrowerkzeuge GmbH) inSteinheim an der Murr.[2] Before the high speed angle grinder of 1954 many other inventors from the early 20th century made many different versions of the grinder to cut different types ofmetal that were hard to cut by hand and were almost impossible to work with. As theavailability of electricpower tools became affordable, angle grinders became a popular tool forworkshops and with the invention ofcordless angle grinders popularity has spiked.[3]
In German, Dutch, Slovak, Czech, Polish, Croatian, Romanian, Hungarian, Bulgarian and Latvian, an angle grinder is colloquially called a "flex", and in Italy and in Spanish-speaking countries it is sometimes called "flexible". InSwitzerland it is known as "Perles" from a popular brand ofcutting tools. The Finnish word "rälläkkä" comes from the sound "rällä-rällä". The Estonian name "relakas" comes from the Finnish name. In Polish it is also known as "kątówka"[4] or "gumówka"[5] (= the rubber thing), which refers to the elasticity of certain types of disks. However they are never made out of true rubber due to fire hazard. In Russian, it is known as "болгарка" ("bolgarka")[6] (literally "Bulgarian" of the feminine gender), since the first angle grinders in theUSSR were Bulgarian made.[7]
Angle grinders can be powered by anelectric motor orcompressed air. The motor drives a geared head at a right-angle, on which can be mounted anabrasivedisc or a thinner cut-off disc, either of which can be replaced when worn. Angle grinders typically have an adjustable guard and a side-handle for two-handed operation. Certain angle grinders, depending on their speed range, can be used assanders, employing a sanding disc with a backing pad or disc. The backing system is typically made of hard plastic, phenolic resin, or medium-hard rubber, depending on the amount of flexibility desired.
Although developed originally as tools for rigid abrasive discs, the availability of an interchangeable power source has encouraged their use with a wide variety of cutters and attachments.
Angle grinders are used inmetal fabrication shops, onconstruction sites,[citation needed]machine shops, along withdie grinders andbench grinders.[citation needed]
There are different discs for different tasks, cut-off discs (diamond blade), abrasive grinding discs,grinding stones, sanding discs,wire brush wheels and polishing pads.[citation needed] Angle grinders have largebearings to counter the side forces generated, unlike a powerdrill, where the force is axial.
Angle grinders are widely used inmetalworking,construction, emergency rescue, and the theft of bicycles. Generally, they are found in workshops, service garages and auto body repair shops. There are a large variety of angle grinders with different disc sizes and power sources:battery,corded orpneumatic. Other variables include the motor power and speed,rpm, andarbor size. Generally, disc size and power increase together. Disc size is usually measured in inches or millimetres. Common disc sizes for angle grinders in the United States include 4, 4.5, 5, 6, 7, 9 and 12 inches, with the most popular sizes being the 4.5 and 5" size. OutsideNorth America, the most common sizes for angle grinder discs are 115 and 125 millimetres.
Discs for pneumatic grinders are much smaller. Pneumatic grinders are generally used for lighter-duty jobs in which moreprecision is required. This is because pneumatic grinders can be powerful while being small and light, because they do not contain heavycopper motorwindings. It is harder for an electric grinder to maintain adequate power with smaller size. Electric grinders are more commonly used for larger, heavy duty jobs. However, there are also small electric grinders and large pneumatic grinders.
Angle grinders have been used to removewheel clamps from vehicles.[8][9]
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Use of angle grinder can emit a large amount of small respirable dust.[10][11][12] Excessive dust emission is regulated byair pollution laws andviolation can result in fines. Proper use of well-designeddust collectors (e.g.dust collection hoods) can reduce dust concentration significantly (up to 80-90%).[10]
The disc type (fibre disc or grinding wheel) affects the dust's size distribution. The dust emitted can be as small asPM1.[13]
The use of an angle grinder in cutting is not preferred, because large amounts of harmful sparks, fumes andparticulates are generated when compared with usingreciprocating saw orband saw.[14] Angle grinders producesparks when cuttingferrous metals. They also produceshards when cutting other materials. The blades themselves may break, which is a hazard to theface andeyes especially, as well as other parts of the body. Consequently, a full face shield and otherprotective clothing must be worn. Angle grinders should never be used without their guard or handle attached. Allworkpieces should be securely clamped or held firmly in avise.[15] In asound pressure level andvibration study conducted by the USNational Institute for Occupational Safety and Health, grinders under an unloaded condition created noise which ranged from 91 to 103dBA.[16]
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