Abrasive machining
Encyclopedia
Abrasive machining is a machining
process where material is removed from a workpiece using a multitude of small abrasive
particles. Common examples include grinding, honing, and polishing. Abrasive processes are usually expensive, but capable of tighter tolerances and better surface finish than other machining processes.
In bonded abrasive processes, the particles are held together within a matrix, and their combined shape determines the geometry of the finished workpiece. For example, in grinding the particles are bonded together in a wheel. As the grinding wheel is fed into the part, its shape is transferred onto the workpiece.
In loose abrasive processes, there is no structure connecting the grains. They may be applied without lubrication as dry powder, or they may be mixed with a lubricant to form a slurry. Since the grains can move independently, they must be forced into the workpiece with another object like a polishing cloth or a lapping plate.
Common abrasive processes are listed below.
Conventional abrasive materials have been used by man since the advent of machining. They are made of materials that exist naturally on Earth, and they are abundant and cheap. Conventional abrasives can suitably machine most materials.
Superabrasives are much harder than conventional abrasives. Since they are much more expensive, they are used when conventional abrasives will not suffice.
Common abrasives are listed below.
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...
process where material is removed from a workpiece using a multitude of small abrasive
Abrasive
An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away...
particles. Common examples include grinding, honing, and polishing. Abrasive processes are usually expensive, but capable of tighter tolerances and better surface finish than other machining processes.
Mechanics of abrasive machining
Abrasive machining works by forcing the abrasive particles, or grains, into the surface of the workpiece so that each particle cuts away a small bit of material. Abrasive machining is similar to conventional machining, such as milling or turning, because each of the abrasive particles acts like a miniature cutting tool. However, unlike conventional machining the grains are much smaller than a cutting tool, and the geometry and orientation of individual grains are not well defined. As a result, abrasive machining is less power efficient and generates more heat.Abrasive machining processes
Abrasive machining processes can be divided into two categories based on how the grains are applied to the workpiece.In bonded abrasive processes, the particles are held together within a matrix, and their combined shape determines the geometry of the finished workpiece. For example, in grinding the particles are bonded together in a wheel. As the grinding wheel is fed into the part, its shape is transferred onto the workpiece.
In loose abrasive processes, there is no structure connecting the grains. They may be applied without lubrication as dry powder, or they may be mixed with a lubricant to form a slurry. Since the grains can move independently, they must be forced into the workpiece with another object like a polishing cloth or a lapping plate.
Common abrasive processes are listed below.
Fixed (bonded) abrasive processes
- GrindingGrinding (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...
- HoningHoning (metalworking)Honing is an abrasive machining process that produces a precision surface on a metal workpiece by scrubbing an abrasive stone against it along a controlled path...
, superfinishingSuperfinishingSuperfinishing, also known as micromachining and short-stroke honing, is a metalworking process that improves surface finish and workpiece geometry. This is achieved by removing just the thin amorphous surface layer left by the last process with an abrasive stone; this layer is usually about... - Tape finishing, abrasive belt machining
- Buffing, brushing
- Abrasive sawing, Diamond wire cutting, Wire sawWire sawA wire saw is a machine using a metal wire or cable for cutting. There are two types of wire saw machines: continuous and oscillating . Sometimes the wire itself is referred to as a "blade"....
- SandingSandpaperSandpaper, also known as glasspaper, is a heavy paper with abrasive material attached to its surface.Sandpaper is part of the "coated abrasives" family of abrasive products. It is used to remove small amounts of material from surfaces, either to make them smoother , to remove a layer of material...
Loose abrasive processes
- PolishingPolishingPolishing is the process of creating a smooth and shiny surface by rubbing it or using a chemical action, leaving a surface with a significant specular reflection In some materials polishing is also able to reduce diffuse reflection to...
- LappingLappingLapping is a machining operation, in which two surfaces are rubbed together with an abrasive between them, by hand movement or by way of a machine.This can take two forms...
- Abrasive flow machiningAbrasive Flow MachiningAbrasive flow machining , also known as extrude honing, is a method of smoothing and polishing internal surfaces and producing controlled radii. A one-way or two-way flow of an abrasive media is extruded through a workpiece, smoothing and finishing rough surfaces. One-way systems flow the media...
(AFM) - Hydro-erosive grindingHydro-erosive grindingHydro-erosive grinding is a process for radiusing orifice edges and hole intersections by flowing an abrasive fluid through. This process can calibrate the holes to flow a certain static flow rate.-External links:...
- Water-jet cutting
- Abrasive blastingAbrasive blastingAbrasive blasting is the operation of forcibly propelling a stream of abrasive material against a surface under high pressure to smooth a rough surface, roughen a smooth surface, shape a surface, or remove surface contaminants. A pressurized fluid, typically air, or a centrifugal wheel is used to...
- Mass finishingMass finishingMass finishing is a group of manufacturing processes that allow large quantities of parts to be simultaneously finished. The goal of this type of finishing is to burnish, deburr, clean, radius, de-flash, descale, remove rust, polish, brighten, surface harden, prepare parts for further finishing, or...
, tumbling- Open barrel tumbling
- Vibratory bowl tumbling
- Centrifugal disc tumbling
- Centrifugal barrel tumbling
Abrasives
The most important property of an abrasive is its hardness. For abrasive grains to effectively cut, they must be significantly harder than the workpiece material. They can be grouped based on their hardness into two categories: conventional abrasives and superabrasives.Conventional abrasive materials have been used by man since the advent of machining. They are made of materials that exist naturally on Earth, and they are abundant and cheap. Conventional abrasives can suitably machine most materials.
Superabrasives are much harder than conventional abrasives. Since they are much more expensive, they are used when conventional abrasives will not suffice.
Common abrasives are listed below.
Conventional
- Aluminum oxide (CorundumCorundumCorundum is a crystalline form of aluminium oxide with traces of iron, titanium and chromium. It is a rock-forming mineral. It is one of the naturally clear transparent materials, but can have different colors when impurities are present. Transparent specimens are used as gems, called ruby if red...
) - Silicon carbideSilicon carbideSilicon carbide , also known as carborundum, is a compound of silicon and carbon with chemical formula SiC. It occurs in nature as the extremely rare mineral moissanite. Silicon carbide powder has been mass-produced since 1893 for use as an abrasive...
- EmeryEmeryEmery may refer to:* Emery ** Emery paper** Emery board, nail filers* Emery , a post-hardcore band from Rock Hill, South Carolina* Emery Theatre, a historic multi-purpose theatre in Cincinnati, Ohio* Emery Worldwide, a cargo airline...
- PumicePumicePumice is a textural term for a volcanic rock that is a solidified frothy lava typically created when super-heated, highly pressurized rock is violently ejected from a volcano. It can be formed when lava and water are mixed. This unusual formation is due to the simultaneous actions of rapid...
- SandSandSand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
- Steel abrasiveSteel abrasiveSteel abrasives are steel particles that are used as abrasive or peening media. They are usually available in two different shapes that address different industrial applications....