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 by friction . While finishing a material often means polishing it to gain a smooth, reflective surface, the process can also involve roughening as in satin, matte or beaded finishes. In short, the ceramics which are used to cut, grind and polish other softer materials are known as abrasives.
41-448: Carborundum Universal Ltd ( CUMI ) is an Indian company which manufactures and develops abrasives , ceramics , refractories , aluminium oxide grains, machine tools , polymers , adhesives and electro minerals in India. It is a part of the great Murugappa Group . The company has subsidiaries in India, Russia, South Africa, Australia, China, Thailand and Canada. CUMI was established as
82-467: A 12MW Hydroelectric power plant at Maniyar , Kerala in 1994 and a 5.5MW Wind mill at Nallur. CUMI made a technology transfer with Answer Technology Inc., USA for advanced monolithics and a technical collaboration with National Institute for Interdisciplinary Science and Technology of India, Bhabha Atomic Research Centre of India and Pennsylvania State University of USA for the development of advanced ceramic technology. CUMI Direct CUMI Direct
123-494: A brass mirror may be cut with a bonded abrasive, have its surface flattened with a coated abrasive to achieve a basic shape, and then have finer grades of abrasive successively applied culminating in a wax paste impregnated with rouge to leave a sort of "grainless finish" called, in this case, a "mirror finish". Also, different shapes of adhesive may make it harder to abrade certain areas of the workpiece. Health hazards can arise from any dust produced (which may be ameliorated through
164-490: A different grade of grit. Grinding wheels are cylinders that are rotated at high speed. While once worked with a foot pedal or hand crank, the introduction of electric motors has made it necessary to construct the wheel to withstand greater radial stress to prevent the wheel flying apart as it spins. Similar issues arise with cutting wheels , which are often structurally reinforced with impregnated fibres. High relative speed between abrasive and workpiece often makes necessary
205-559: A natural mineral, differing only in that the synthetic mineral has been manufactured rather than mined. Impurities in the natural mineral may make it less effective. Some naturally occurring abrasives are: Some abrasive minerals (such as zirconia alumina ) occur naturally but are sufficiently rare or sufficiently more difficult or costly to obtain such that a synthetic stone is used industrially. These and other artificial abrasives include: Abrasives are shaped for various purposes. Natural abrasives are often sold as dressed stones, usually in
246-404: A process called sandblasting (or similar, such as the use of glass beads which is "bead blasting"). Dry ice will sublimate leaving behind no residual abrasive. Cutting compound used on automotive paint is an example of an abrasive suspended in a liquid, paste or wax, as are some polishing liquids for silverware and optical media . The liquid, paste or wax acts as a binding agent that keeps
287-637: A result of diversification from banking business through cycle manufacturing with the intent to manufacture abrasive materials . CUMI's parent company , the Murugappa Group , made a tie up with the Carborundum, UK, a subsidiary of American abrasive manufacturer, Carborundum, USA and the Universal Grinding Co. Ltd., UK in 1950. The result was the Carborundum Universal of Madras . Then it
328-468: A smooth and shiny surface by rubbing it or by applying a chemical treatment, leaving a clean surface with a significant specular reflection (still limited by the index of refraction of the material according to the Fresnel equations ). In some materials (such as metals, glasses, black or transparent stones), polishing is also able to reduce diffuse reflection to minimal values. When an unpolished surface
369-449: A subsidiary of CUMI Besides manufacturing, marketing and distribution CUMI also involved in a diversified works like mining , power generation and TOT agreements with various organizations. CUMI acquired Bauxite mines at Bhatia and Okha of Gujarat in India, Silicon Carbide plant in Koratty , Kerala and a Brown Aluminium Oxide grains Plant at Edapally , Kerala, India. CUMI established
410-485: A sufficiently small size (anywhere from macroscopic grains as large as about 2 mm to microscopic grains about 0.001 mm in diameter) to permit their use as an abrasive. These grains, commonly called grit, have rough edges, often terminating in points which will decrease the surface area in contact and increase the localised contact pressure . The abrasive and the material to be worked are brought into contact while in relative motion to each other. Force applied through
451-692: A very fine compound, the principle being that a multitude of small scratches will be more optically transparent than a single large scratch. However, this does take some skill and will eventually cause the protective coating of the disc to be entirely eroded (especially if the original scratch is deep), at which time, the data surface will be destroyed if abrasion continues. Silicon carbide powders are commonly used as abrasive materials in various machining processes, including grinding, water-jet cutting , and sandblasting . These powders are effective for fine grinding or rough polishing of semiconductors , ceramics , and ferrous materials. The shape, size and nature of
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#1732863110812492-482: Is magnified thousands of times, it usually looks like a succession of mountains and valleys. By repeated abrasion, those "mountains" are worn down until they are flat or just small "hills". The process of polishing with abrasives starts with a coarse grain size and gradually proceeds to the finer ones to efficiently flatten the surface imperfections and to obtain optimal results. The strength of polished products can be higher than their unpolished counterparts owing to
533-767: Is a very common coated abrasive. Coated abrasives are most commonly the same minerals as are used for bonded abrasives. A bonding agent (often some sort of adhesive or resin) is applied to the backing to provide a flat surface to which the grit is then subsequently adhered. A woven backing may also use a filler agent (again, often a resin) to provide additional resilience. Coated abrasives may be shaped for use in rotary and orbital sanders, for wrapping around sanding blocks, as handpads, as closed loops for use on belt grinders , as striking surfaces on matchboxes , on diamond plates and diamond steels. Diamond tools , though for cutting, are often abrasive in nature. Sand, glass beads, metal pellets copper slag and dry ice may all be used for
574-401: Is called a binder and is often a clay , a resin , a glass or a rubber . This mixture of binder and abrasive is typically shaped into blocks, sticks, or wheels. The most common abrasive used is aluminium oxide. Also common are silicon carbide, tungsten carbide and garnet . Artificial sharpening stones are often a bonded abrasive and are readily available as a two sided block, each side being
615-445: Is expensive due to scarcity in nature and the cost of synthesising it. Bauxite is a very common ore which, along with corundum's reasonably high hardness, contributes to corundum's status as a common, inexpensive abrasive. Thought must be given to the desired task about using an appropriately hard abrasive. At one end, using an excessively hard abrasive wastes money by wearing it down when a cheaper, less hard abrasive would suffice. At
656-611: Is not strictly necessary, as any two solid materials that repeatedly rub against each other will tend to wear each other away; examples include, softer shoe soles wearing away wooden or stone steps over decades or centuries or glaciers abrading stone valleys. Typically, materials used as abrasives are either hard minerals (rated at 7 or above on Mohs scale of mineral hardness ) or are synthetic stones, some of which may be chemically and physically identical to naturally occurring minerals but which cannot be called minerals as they did not arise naturally. (While useful for comparative purposes,
697-410: Is the cleaning of the waste material (swarf and loose abrasive) from the surface and exposing fresh grit. Depending upon the abrasive and how it was used, dressing may involve the abrasive being simply placed under running water and brushed with a stiff brush for a soft stone or the abrasive being ground against another abrasive, such as aluminium oxide used to dress a grinding wheel. Truing is restoring
738-440: The inner tube rather than the tyre) require use of an abrasive so that the self- vulcanising cement will stick strongly. Inadvertently, people who use knives on glass or metal cutting boards are abrading their knife blades. The pressure at the knife edge can easily create microscopic (or even macroscopic) cuts in the board. This cut is a ready source of abrasive material as well as a channel full of this abrasive through which
779-620: The Eastern Abrasives Ltd, Kolkata in 1978. In 1997 Cutfast Abrasive Tools Ltd, Eastern Abrasive Ltd, Cutfast Polymers Ltd and Carborundum Universal Investment are joined with Carborundum Universal Ltd. With in a year of acquisition of Sterling Abrasives Ltd and SEDCO in 2003, CUMI acquired CUMI Australia Pty Ltd., Australia. In 2007 the company took over a china based firm Sanhe Yanjiao Jingri Diamond Industrial Company Ltd and Russian Volzhsky Abrasive Works. The further acquisitions are followed in 2008, Foskor Zirconia Ltd, South Africa became
820-529: The Mohs scale is of limited value to materials engineers as it is an arbitrary, ordinal, irregular scale.) Diamond , a common abrasive, for instance occurs both naturally and is industrially produced, as is corundum which occurs naturally but which is nowadays more commonly manufactured from bauxite . However, even softer minerals like calcium carbonate are used as abrasives, such as "polishing agents" in toothpaste. These minerals are either crushed or are already of
861-413: The abrasive attached to the cloth which is used as a backing to move the abrasive across the work piece. On cars in particular, wax may serve as both a protective agent by preventing exposure of the paint of metal to air and also act as an optical filler to make scratches less noticeable. Toothpaste contains calcium carbonate or silica as a "polishing agent" to remove plaque and other matter from teeth as
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#1732863110812902-400: The abrasive is itself abraded. This allows fine abrasives to be used in the polishing of metal and lenses where the series of increasingly fine scratches tends to take on a much more shiny or reflective appearance or greater transparency . Very fine abrasives may be used to coat the strop for a cut-throat razors , however, the purpose of stropping is not to abrade material but to straighten
943-482: The abrasive to its original surface shape. Wheels and stones tend to wear unevenly, leaving the cutting surface no longer flat (said to be "dished out" if it is meant to be a flat stone) or no longer the same diameter across the cutting face. This will lead to uneven abrasion and other difficulties. A coated abrasive comprises an abrasive fixed to a backing material such as paper , cloth , rubber, resin, polyester or even metal , many of which are flexible. Sandpaper
984-726: The bottom of the tableware, which is often unglazed in part or in whole and acts as simply another bonded abrasive. Metal pots and stoves are often scoured with abrasive cleaners, typically in the form of the aforementioned cream or paste or of steel wool and non woven scouring pads which holds fine grits abrasives. Human skin is also subjected to abrasion in the form of exfoliation. Abrasives for this can be much softer and more exotic than for other purposes and may include things like almond and oatmeal . Dermabrasion and microdermabrasion are now rather commonplace cosmetic procedures which use mineral abrasives. Scratched compact discs and DVDs may sometimes be repaired through buffing with
1025-577: The burr on an edge. The final stage of sharpening Japanese swords is called polishing and may be a form of superfinishing . Different chemical or structural modifications may be made to alter the cutting properties of the abrasive. Other very important considerations are price and availability. Diamond, for a long time considered the hardest substance in existence, is actually softer than fullerite and even harder aggregated diamond nanorods , both of which have been synthesised in laboratories, but no commercial process has yet been developed. Diamond itself
1066-403: The cutting action of sharp teeth which have been cut into the surface of the file, very much like those of a saw . However, diamond files are a form of coated abrasive (as they are metal rods coated with diamond powder). Abrasives generally rely upon a difference in hardness between the abrasive and the material being worked upon, the abrasive being the harder of the two substances. However, it
1107-436: The edge slides. For this reason, and without regard for the health benefits, wooden boards are much more desirable. A similar occurrence arises with glass-cutters . Glass-cutters have circular blades that are designed to roll not slide. They should never retrace an already effected cut. Undesired abrasion may result from the presence of carbon in internal combustion engines . While smaller particles are readily transported by
1148-608: The establishment of Murugappa Morgan Thermal Ceramics Ltd in 1982. The company has laid a strong foundation in Engineered Ceramics through number of joint ventures. In 1991 Wendt (India) Ltd, a joint ventured company of Wendt GmbH, Germany and The House of Khataus, was merged with the CUMI. CUMI's first Industrial Ceramics division was established in Hosur , Tamil Nadu as a technical partnership with Coors Ceramics , USA in 1991. Later it
1189-413: The form of a rectangular block. Both natural and synthetic abrasives are commonly available in a wide variety of shapes, often coming as bonded or coated abrasives, including blocks, belts, discs, wheels, sheets, rods and loose grains. A bonded abrasive is composed of an abrasive material contained within a matrix , although very fine aluminium oxide abrasive may comprise sintered material. This matrix
1230-551: The grains causes fragments of the worked material to break away, while simultaneously smoothing the abrasive grain and/or causing the grain to work loose from the rest of the abrasive. Some factors which will affect how quickly a substance is abraded include: Abrasives may be classified as either natural or synthetic. When discussing sharpening stones , natural stones have long been considered superior but advances in material technology are seeing this distinction become less distinct. Many synthetic abrasives are effectively identical to
1271-653: The hardness of calcium carbonate is less than that of tooth enamel but more than that of the contaminating agent. Very fine rouge powder was commonly used for grinding glass, being somewhat replaced by modern ceramics, and is still used in jewellery making for a highly reflective finish. Cleaning products may also contain abrasives suspended in a paste or cream. They are chosen to be reasonably safe on some linoleum , tile , metal or stone surfaces. However, many laminate surfaces and ceramic topped stoves are easily damaged by these abrasive compounds. Even ceramic/pottery tableware or cookware can damage these surfaces, particularly
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1312-402: The lubrication system, larger carbon particles may abrade components with close tolerances . The carbon arises from the excessive heating of engine oil or from incomplete combustion . This soot may contain fullerenes which are noted for their extreme hardness—and small size and limited quantity which would tend to limit their effect. Polishing Polishing is the process of creating
1353-573: The other end, if the abrasive substance is too soft, abrasion does not take place in a timely fashion, effectively wasting the abrasive as well as any accruing costs associated with loss of time. Aside from the aforementioned uses of shaping and finishing, abrasives may also be used to prepare surfaces for application of some sort of paint of adhesive. An excessively smooth surface may prevent paint and adhesives from adhering as strongly as an irregular surface could allow. Inflatable tyre repair kits (which, on bicycles particularly, are actually patches for
1394-426: The presence of scratches may: A finer or softer abrasive will tend to leave much finer scratch marks which may even be invisible to the naked eye (a "grainless finish"); a softer abrasive may not even significantly abrade a certain object. A softer or finer abrasive will take longer to cut, as it tends to cut less deeply than a coarser, harder material. Also, the softer abrasive may become less effective more quickly as
1435-834: The raw materials for abrasives and refractories by the Electrominerals division. Abrasive Abrasives are extremely commonplace and are used very extensively in a wide variety of industrial, domestic, and technological applications. This gives rise to a large variation in the physical and chemical composition of abrasives as well as the shape of the abrasive. Some common uses for abrasives include grinding , polishing, buffing , honing , cutting , drilling , sharpening , lapping , and sanding (see abrasive machining ). (For simplicity, "mineral" in this article will be used loosely to refer to both minerals and mineral-like substances whether man-made or not.) Files are not abrasives; they remove material not by scratching or rubbing, but by
1476-751: The use of a lubricant of some kind. Traditionally, they were called coolants as they were used to prevent frictional heat build up which could damage the workpiece (such as ruining the temper of a blade). Some research suggests that the heat transport property of a lubricant is less important when dealing with metals as the metal will quickly conduct heat from the work surface. More important are their effects upon lessening tensile stresses while increasing some compressive stresses and reducing "thermal and mechanical stresses during chip formation". Various shapes are also used as heads on rotary tools used in precision work, such as scale modelling . Bonded abrasives need to be trued and dressed after they are used. Dressing
1517-521: The use of a lubricant) which could lead to silicosis (when the abrasive or workpiece is a silicate ) and the choice of any lubricant. Besides water, oils are the most common lubricants. These may present inhalation hazards, contact hazards and, as friction necessarily produces heat, flammable material hazards. An abrasive which is too hard or too coarse can remove too much material or leave undesired scratch marks. Besides being unsightly, scratching can have other, more serious effects. Excessive abrasion or
1558-411: The workpiece and the desired finish will influence the choice of the abrasive used. A bonded abrasive grind wheel may be used to commercially sharpen a knife (producing a hollow grind ), but an individual may then sharpen the same knife with a natural sharpening stone or an even flexible coated abrasive (like a sandpaper) stuck to a soft, non-slip surface to make achieving a convex grind easier. Similarly,
1599-606: Was expanded with the unique Metallized Cylinders Plant. As a part of expanding their presence, in 2005 the company started CUMI Middle East FZE in Ras Al Khaimah. In order to strengthen their global presence CUMI bought Abrasive Enterprises Inc., Canada, for $ 2.24 Million by 2006. After a year CUMI established CUMI International Ltd in Cyprus. With in a decade, after the withdrawal of the collaborators, CUMI acquired Ajax Products Pvt Ltd. CUMI stepped up in abrasive industries by acquiring
1640-511: Was renamed and incorporated in 1954 as Carborundum Universal Ltd (CUMI). Initially CUMI was founded to manufacture the core products for the collaborating companies. Later the company established its first bonded abrasive plant at Chennai with the facility acquired from Ajax Products and began its manufacturing in the abrasives platform. With the intention of producing technical ceramics for high temperature insulation products CUMI has made joint venture with Morgan Crucible Plc. UK resulted in
1681-555: Was started in the year of 2005. CUMI direct is selling Most of the products are granted CE and GS certificates. The major divisions are: The range of applications of different divisions like material removal, polishing the rough surface, fine finishing by the Abrasives division, wear resistant, heat resistant, liners and metallized ceramics by the Ceramics division, heat resistant, containment products from Super refractories division and