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Metal swarf, also known as chips or by other process-specific names (such as turnings, filings, or shavings), are pieces of metal that are the debris or waste resulting from machining or similar subtractive (material-removing) manufacturing processes. Metal swarf can be small particles (such as the gritty swarf from grinding metal) or long, stringy tendrils (such as the springy chips from turning tough metals).
Chips can be extremely sharp, and this creates a safety problem, as they can cause serious injuries if not handled correctly. Depending on the composition of the material, it can persist in the environment for a long time before degrading. This, combined with the small size of some chips (e.g. those of brass or bronze), allows them to disperse widely by piggy-backing on soft materials and also to penetrate the skin as deep splinters.
It is standard training for machinists, and usually a standing workplace rule, to avoid handling swarf with bare hands. Similarly, it is also standard training for machinists, and usually a standing workplace rule, to minimize or entirely avoid handling swarf by blowing chips away with compressed air, but this practice can potentially damage the machine by causing chips to get jammed in and then embedded into the moving surfaces leading to degradation of the machine's precision. Alternatives to blowing chips away include vacuuming them away with an industrial vacuum (shop vacuum); gently washing them away with a coolant hose discharging at typical garden-hose pressures; or preventing their generation in the first place (for example, forming threads instead of cutting them). Some machine tool manuals proscribe these practices both for safety and for the preservation of way wipers and bearing seals.
It is not uncommon for chips flying off the cutter to be ejected with great force and to fly several metres. These flying chips present a hazard that is deflected with safety glasses, face shields, and other personal protective equipment, as well as the sheet-metal enclosures (and polycarbonate windows) that surround most commercial computer numerical control (CNC) machine tools.
Due to its high surface area, swarf composed of some reactive metals can be highly flammable. Caution should be exercised to avoid ignition sources when handling or storing swarf in loose form, especially swarf of pure magnesium, magnesium alloy, pure titanium, titanium alloy, iron, and non-stainless steel.
Swarf stored in piles or bins may also spontaneously combust, especially if the swarf is coated with cutting oil. [2]
To extinguish swarf fires, a special fire extinguisher is needed, designed for fighting Class D (metal) fires.
Some common engineering materials such as beryllium are hazardous when finely divided and appropriate measures should be taken to prevent exposure.
Optimum cutting efficiencies often generate long spring-like swarf. This is hard to deal with as it is bulky and can clog the nozzle of a shop vac. Clean-up and disposal of this continuous-cutting swarf is made simpler by using a cutting tool with a chip-breaker. This results in denser, more manageable waste. Chip breaking tool geometry is generally designed to break the chip by having it curl back onto itself. This action produces many small spiral shaped rings instead of one long helical chip. "Number Nine" shaped chips or short swarf in general are preferred also because it helps prevent entangling the rotating machine.
Disposing of swarf is a tedious but necessary task. For ease of transport and handling, swarf may be compressed into bricks, which greatly reduces associated problems with storing and cost; it also improves material handling for all concerned with its reclamation and recycling.
Metal swarf can usually be recycled, and this is the preferred method of disposal due to the environmental concerns regarding potential contamination with cutting fluid or tramp oil. The ideal way to remove these liquids is by the use of a centrifuge which will separate the fluids from the metal, allowing both to be reclaimed and prepared for further treatment. Small bundles of stainless steel or bronze swarf are sold as excellent scourers for dishwashing or cleaning encrustations of dirt. Recycling chips rather than putting them in the garbage stream (heading to landfilling or incineration) has various advantages:
Machine shops are typically required by the scrap collector to:
Cutting fluid is a type of coolant and lubricant designed specifically for metalworking processes, such as machining and stamping. There are various kinds of cutting fluids, which include oils, oil-water emulsions, pastes, gels, aerosols (mists), and air or other gases. Cutting fluids are made from petroleum distillates, animal fats, plant oils, water and air, or other raw ingredients. Depending on context and on which type of cutting fluid is being considered, it may be referred to as cutting fluid, cutting oil, cutting compound, coolant, or lubricant.
Metalworking is the process of shaping and reshaping metals to create useful objects, parts, assemblies, and large scale structures. As a term it covers a wide and diverse range of processes, skills, and tools for producing objects on every scale: from huge ships, buildings, and bridges down to precise engine parts and delicate jewelry.
Taps and dies are tools used to create screw threads, which is called threading. Many are cutting tools; others are forming tools. A tap is used to cut or form the female portion of the mating pair. A die is used to cut or form the male portion of the mating pair. The process of cutting or forming threads using a tap is called tapping, whereas the process using a die is called threading.
A machinist is a tradesperson or trained professional who not only operates machine tools but also has the knowledge of tooling and materials required to create set ups on machine tools such as milling machines, grinders, lathes, and drilling machines.
Machining is a process in which a material is cut to a desired final shape and size by a controlled material-removal process. The processes that have this common theme are collectively called subtractive manufacturing, in contrast to additive manufacturing, which uses controlled addition of material. Exactly what the "controlled" part of the definition implies can vary, but it usually implies the use of machine tools.
A cermet is a composite material composed of ceramic (cer) and metal (met) materials.
Extrusion is a process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section. Its two main advantages over other manufacturing processes are its ability to create very complex cross-sections; and to work materials that are brittle, because the material encounters only compressive and shear stresses. It also creates excellent surface finish and gives considerable freedom of form in the design process.
Drilling is a cutting process that uses a drill bit to cut a hole of circular cross-section in solid materials. The drill bit is usually a rotary cutting tool, often multi-point. The bit is pressed against the work-piece and rotated at rates from hundreds to thousands of revolutions per minute. This forces the cutting edge against the work-piece, cutting off chips (swarf) from the hole as it is drilled.
Scrap consists of recyclable materials left over from product manufacturing and consumption, such as parts of vehicles, building supplies, and surplus materials. Unlike waste, scrap has monetary value, especially recovered metals, and non-metallic materials are also recovered for recycling.
Milling cutters are cutting tools typically used in milling machines or machining centres to perform milling operations. They remove material by their movement within the machine or directly from the cutter's shape.
David J. Gingery was an inventor, writer, and machinist, best known for his series of books on how to build machine tools.
Aluminium recycling is the process by which scrap aluminium can be reused in products after its initial production. The process involves simply re-melting the metal, which is far less expensive and energy-intensive than creating new aluminium through the electrolysis of aluminium oxide, which must first be mined from bauxite ore and then refined into aluminium oxide using the Bayer process and then refined again into aluminium metal using the Hall–Héroult process.
Swarf, also known as chips or by other process-specific names, are pieces of metal, wood, or plastic that are the debris or waste resulting from machining, woodworking, or similar subtractive (material-removing) manufacturing processes. Swarf or chips can be small particles ; long, stringy tendrils ; slag-like waste ; or stone fragments and dust.
A cold saw is a circular saw designed to cut metal which uses a toothed blade to transfer the heat generated by cutting to the chips created by the saw blade, allowing both the blade and material being cut to remain cool. This is in contrast to an abrasive saw, which abrades the metal and generates a great deal of heat absorbed by the material being cut and saw blade.
Semi-solid metal casting (SSM) is a near net shape variant of die casting. The process is used today with non-ferrous metals, such as aluminium, copper, and magnesium, but also can work with higher temperature alloys for which no currently suitable die materials are available. The process combines the advantages of casting and forging. The process is named after the fluid property thixotropy, which is the phenomenon that allows this process to work. Simply, thixotropic fluids flow when sheared, but thicken when standing. The potential for this type of process was first recognized in the early 1970s. There are three different processes: thixocasting, rheocasting, thixomolding. SIMA refers to a specialized process to prepare aluminum alloys for thixocasting using hot and cold working.
Grinding is a type of abrasive machining process which uses grinding wheel as cutting tool.
IMCO Carbide Tool is an American manufacturing company that researches, designs and manufactures high-performance cutting tools for a variety of applications in the aerospace, automotive, medical, petrochemical, and manufacturing industries. Founded in 1977 by Lawrence R. Osburn and headquartered in Perrysburg Twp, Ohio, IMCO serves a diverse customer base of small job shops to large production operations around the world.
An inclusion is a solid particle in liquid aluminium alloy. It is usually non-metallic and can be of different nature depending on its source.
Chip formation is part of the process of cutting materials by mechanical means, using tools such as saws, lathes and milling cutters. An understanding of the theory and engineering of this formation is an essential part of the development of such machines and their cutting tools.
Friction extrusion is a thermo-mechanical process that can be used to form fully consolidated wire, rods, tubes, or other non-circular metal shapes directly from a variety of precursor charges including metal powder, flake, machining waste or solid billet. The process imparts unique, and potentially, highly desirable microstructures to the resulting products. Friction extrusion was invented at The Welding Institute in the UK and patented in 1991. It was originally intended primarily as a method for production of homogenous microstructures and particle distributions in metal matrix composite materials.