Grinding wheel
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(June 2008)
A grinding wheel is an expendable wheel that is composed of an abrasive compound. These wheels are used in grinding machines.
Contents
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1 Compo sition and manufc ture 2 Functio ns 3 Safety • 3 . 1 F l a n g e s c l a m p i n g f o r c e
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4 Types of grindin g wheels • 4 . 1
[edit] Composition and manufacture
The wheel is generally made from a matrix of coarse particles pressed and bonded together to form a solid, circular shape, various profiles and cross sections are available depending on the intended usage for the wheel. They may also be made from a solid steel or aluminium disc with particles bonded to the surface. Materials used are generally silicon carbide and diamond with a vitrified bonding agent. In production grinding, a wide array of materials is used. Wheels with different abrasives, structure, bond, grade, and grain sizes are available. The abrasive is the actual cutting material, such as cubic boron nitride, zirconia aluminum oxide, manufactured diamonds, ceramic aluminum oxide, aluminum oxide, and others. The abrasive is selected based on the hardness of the material being cut. The structure of the wheel refers to the density of the wheel (bond and abrasive versus airspace). A less-dense wheel will cut freely, and has a large effect on surface finish. A less dense wheel is able to take a deeper or wider cut with less coolant, as the chip clearance on the wheel is greater. The grade of the wheel determines how tightly the bond holds the abrasive. Grade affects almost all considerations of grinding, such as wheel speed, coolant flow, maximum and minimum feed rates, and grinding depth. Grain size determines the physical abrasive size in the wheel. A larger grain will cut freely, allowing fast cutting but poor surface finish. Ultra-fine grain sizes are for precision finish work, where a fine surface finish is required. The wheel bonding agent determines how the wheel holds the abrasives. This affects finish, coolant, and minimum/maximum wheel speed. The manufacture of these wheels is a precise and tightly controlled process, due not only to the inherent safety risks of a spinning disc, but also the composition and uniformity required to prevent that disc from exploding due to the high stresses produced on rotation.
[edit] Functions
Grinding wheels are self sharpening to a small degree, for optimal use they may be dressed and trued by the use of grinding dressers. Dressing the wheel refers to removing the current layer of abrasive, so that a fresh and sharp surface is exposed to the work surface. Truing the wheel makes the grinding surface parallel to the grinding table or other reference plane, so the entire grinding wheel is even and produces an accurate surface. The wheel type (eg:- cup or plain wheel below) fit freely on their supporting arbors, the necessary clamping force to transfer the rotary motion being applied to the wheels side by identically sized flanges (metal discs). The paper blotter shown in the images is intended to distribute this clamping force evenly across the wheels surface.
[edit] Safety
Safety is extremely important at all times, especially when grinding wheels are involved. They are a mainstay of the engineering and construction industry and the risks involved with them may tend to be taken for granted. Safety awareness and an understanding of the materials and processes involved is essential. Appropriate safety gear must be worn and all safety procedures must be followed. Always err on the side of caution. Before mounting and balancing a grinding wheel, the wheel must be sounded. Sounding (otherwise known as a "Ring Check") is loosely suspending the wheel by a bit of twine or other material so that it hangs free, and giving the wheel a very light tap with a non metallic object, such as a wooden stick. Care must be taken not to damage the wheel when sounding. A wheel that is safe to use will ring
clearly and solidly, like a bell or tuning fork. A damaged wheel will not make any resonating sound, it will sound more like a dull thud. Damaged wheels must not be used under any circumstances and are best discarded or returned to the manufacturer. This process is critically important for surface and diameter grinding, where frequent handling, storage, and changing of wheels increases the risk of fatal wheel damage. Contact with a spinning grinding wheel will produce a cut. Because of the heat generated in the grinding process, a burn might also be produced. Wood should never be ground on a wheel, as it can clog the wheel's pores and cause the wheel to burst, with fatal results.
[edit] Flanges clamping force
The clamping force of the grinding wheel flanges is an important safety parameter of a grinding operation: - it must be high enough to drive the wheel without slippage under the most severe operating conditions of the machine. - it must not apply to the wheel an excessive compression stress which could weaken the wheel. - it must not distort the flanges. This clamping force can be calculated by the formula detailed in the EN13218 standard, Annex C. When flanges are clamped by screws it is essential to know the torque to use when tightening these screws to make sure that the needed clamping force is obtained and that each screw is loaded enough to avoid loosening. For multiple screw flanges this torque calculation is also detailed in the EN13218 standard Annex C. The design of the flanges and their tightening parameters are their manufacturer's responsibility.
[edit] Types of grinding wheels
[edit] Straight wheel
Straight wheel
To the left is an image of a straight wheel. These are by far the most common style of wheel and can be found on bench or pedestal grinders. They are used on the periphery only and therefore produce a slightly concave surface (hollow ground) on the part. This can be used to advantage on many tools such as chisels. Straight Wheels are the kind of generally used for cylindrical, centreless, and surface grinding operations. Wheels of this form vary greatly in size, the diameter and width of face naturally depending upon the class of work for which is used and the size and power of the grinding machine.
[edit] Cylinder or wheel ring
Cylinder wheels provide a long, wide surface with no center mounting support (hollow). They can be very large, up to 12" in width. They are used only in vertical or horizontal spindle grinders. Cylinder or wheel ring is used for producing flat surfaces, the grinding being done with the end face of the wheel.
[edit] Tapered wheel
A straight wheel that tapers outward towards the center of the wheel. This arrangement is stronger than straight wheels and can accept higher lateral loads. Tapered face straight wheel is primarily used for grinding thread, gear teeth etc.
[edit] Straight cup
Straight cup wheels are an alternative to cup wheels in tool and cutter grinders, where having an additional radial grinding surface is beneficial.
[edit] Dish cup
A very shallow cup-style grinding wheel. The thinness allows grinding in slots and crevices. It is used primarily in cutter grinding and jig grinding.
[edit] Saucer wheel
A special grinding profile that is used to grind milling cutters and twist drills. It is most common in non-machining areas, as sawfilers use saucer wheels in the maintenance of saw blades.
[edit] Diamond wheel
Diamond wheel Diamond wheels are grinding wheels with industrial diamonds bonded to the periphery. They are used for grinding extremely hard materials such as carbide tips, gemstones or concrete. The saw pictured to the right is a slitting saw and is designed for slicing hard materials, typically gemstones.
[edit] Diamond mandrels
Diamond mandrels are very similar to their counterpart, a diamond wheel. They are tiny diamond rasps for use in a jig grinder doing profiling work in hard material.
[edit] Cut off wheels
Cut off or parting wheels are self-sharpening wheels that are thin in width and often have radial fibres reinforcing them. They are often used in the construction industry for cutting reinforcement steel (rebar), protruding bolts or anything that needs quick removal or trimming. Most handymen would recognise an angle grinder and the discs they use.
[edit] See also
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Diamond Blade Diamond tools
Grinding Wheels
Grinding wheel is widely used in grinding machines. These wheels are expendable wheels composing of an abrasive compound. These grinding wheels are formed out of an aluminum disc or solid steel by way of attaching the particles to the exterior surface. In general, this grinding wheel is normally prepared using the mold of hard-pressed coarse particles matrix that are allied together to make a firm circular shape. Based on the planned use of the wheel, various profiles and cross sections are also obtainable. In common other materials are made use of with vitrified bonding agent like diamond and silicon carbide. A variety of materials are used in production grinding and primary things available in today’s market are wheels of different grade, various structure, varied abrasives, a range of grain sizes, and mixed link. Abrasive is in fact a cutting material like all other manufactured diamonds, cubic boron nitride, ceramic aluminum oxide and zirconia aluminum oxide. It is advisable to choose an abrasive considering the rigidity of the material that is about to slice. The Wheel structure defines the wheel density that is the abrasive and bond versus airspace. Comparatively it is found a wheel which is of less density cuts freely and this plays a major effect on the finishing of the surface. The above nature is due to better chip clearance of the lesser density wheel. With a wheel that is of less density, we can obtain a wider or deeper cut, by means of less coolant. We can determine the grade of a wheel by studying how closely the abrasive sticks to the bond. The grade has effect on about all aspects of grinding like flow of coolant, speed of wheel, depth of grinding and feed rate ranges. It is the grain which decides the size of a physical abrasive in any wheel. Though a grain which is of greater size cut swiftly without any strain, we would still be able to get only a poor finish of surface. To get a fine & precision surface finish make use of ultra-fine sized grain. Wheel bonding agent is what decides how a wheel holds an abrasive and also has its impact on wheel speed, its finish and coolant flow, etc. Wheel manufacturing is a process that is precise and strictly controlled not only because of the innate security risk of a spinning disc but also depends on the consistency of composition that is required to
stop that particular disc from explosion due to the high stress released at the time of revolving. These grinding wheels have small level of sharpening by itself. To get the best possible use, we have to clad it with the help of grinding dressers. Dressing here means taking out of existing abrasive coating, this exposes a new and razor-sharp surface to the surface of work. Truing method is followed to make the grinding surface flat. It is done for the purpose of getting a parallel grinding surface to the respective table or to the orientation of the plane which could produce perfect surface. The cup or plain wheel rest profusely on the arbors, perfectly sized metal discs at the side of the wheel and apply the essential hold tightly force to transmit the revolving motion. Paper blotter dissolves the force uniformly within the surface of the wheel. Types of grinding wheels Straight Grinding wheels Straight wheel are the most common mode of wheel that is found on pedestal or bench grinders. This is the one widely used for centreless & cylindrical surface grinding operations. As it is used only on the periphery, it forms a little concave surface on the piece. This is used to gain on several tools like chisels. The size of these wheels differs to a great extent, width & diameter of its face obviously depends on the category of its work, machines grinding power. Cylinder or wheel ring A cylinder wheel has no center mounting support but has a long & wide surface. Their width is up to 12" and is used purely in horizontal or vertical spindle grinders. This is used to produce flat surface, here we do grinding with the ending face of the wheel. Tapered Grinding wheels Tapered Grinding wheel is a straight wheel that tapers externally towards the midpoint of the wheel. As this pact is stronger than straight wheels, it accepts advanced lateral loads. Straight wheel with tapered face is chiefly used for gear teeth, grinding thread, etc. Straight cup This Straight cup wheels forms an option for cup wheels in cutter and tool grinders, having an extra radial surface of grinding is favorable. Dish cup In fact this is used primarily in jig grinding and cutter grinding. It is a very thin cup-style grinding wheel which permits grinding in crevices and slot. Saucer Grinding Wheels Saucer Grinding Wheel is an exceptional grinding profile used for grinding twist drills and milling cutters. This finds wide usage in non-machining areas, as this saw filers are used by saucer wheels to maintain saw blades.
Diamond Grinding Wheels In diamond wheels industrial diamonds remain bonded to the edge. This is used to grind hard materials like concrete, gemstones & carbide tips. A slitting saw is designed for slicing gemstones like hard materials.
Class Vocabulary alumina The natural form of aluminum oxide. aluminum oxide An abrasive made by fusing bauxite, iron, and coke that is widely used to grind ferrous materials. The natural form is called corundum. American National Standards Institute A private, non-profit organization that administers and coordinates voluntary standards and systems. arc furnace A heating unit that uses electric arcs between carbon electrodes to melt steel and manufacture abrasives. Also called an electric arc furnace. bauxite A form of aluminum oxide that contains several impurities. bond The "glue" or adhesive material that holds abrasive grains together in a grinding wheel. Bonds may be vitrified, organic, metal, or electroplated. carbide A compound developed by the combination of carbon with usually tungsten, titanium, or tantalum that is used in metal cutting tools for its hardness and wear resistance. carbon steel The basic type of steel, which contains less than 3% of elements other than iron and carbon. cast iron A metal consisting of iron, over 2.11% carbon, and 1 to 3% silicon. Cast irons will normally contain trace amounts of other elements. ceramic aluminum oxide An exceptionally hard, strong, sharp abrasive made from a process in which alumina gel is dried and crushed. Ceramic aluminum oxide has the ability to refracture at the sub-micron level. chemical vapor deposition A method of manufacturing diamonds that uses heat and radio waves or microwaves to break a carbon-rich gas into
Choosing The Right Grinding Wheel
Understanding grinding wheel fundamentals will help you find the right wheel for the job. Article from: Modern Machine Shop, Contributed by: Joe Sullivan, Norton Company Posted on: 12/15/2000 Click Image to Enlarge
Grinding wheels are generally labeled with a maximum safe operating speed. Don't exceed this speed limit. The safest course is not even to mount a given wheel on any grinder fast enough to exceed this limit. The grinding wheel is a cutting tool. It's an abrasive cutting tool. In a grinding wheel, the abrasive performs the same function as the teeth in a saw. But unlike a saw, which has teeth only on its edge, the grinding wheel has abrasive grains distributed throughout the wheel. Thousands of these hard, tough grains move against the workpiece to cut away tiny chips of material. Abrasive suppliers offer a wide array of products for a wide array of grinding applications in metalworking. Choosing the wrong product can cost the shop time and money. This article presents some of the fundamentals of selecting the best grinding wheel for the job.
Abrasives—Grits and Grains
Grinding wheels and other bonded abrasives have two major components-the abrasive grains that do the actual cutting and the bond that holds the grains together and supports them while they cut. The percentages of grain and bond and their spacing in the wheel determine the wheel's structure. The particular abrasive used in a wheel is chosen based on the way it will interact with the work material. The ideal abrasive has the ability to stay sharp with minimal point dulling. When dulling begins, the abrasive fractures, creating new cutting points. Each abrasive type is unique with distinct properties for hardness, strength, fracture toughness and resistance to impact. Aluminum oxide is the most common abrasive used in grinding wheels. It is usually the abrasive chosen for grinding carbon steel, alloy steel, high speed steel, annealed malleable iron, wrought iron, and bronzes and similar metals. There are many different types of aluminum oxide abrasives, each specially made and blended for particular types of grinding jobs. Each abrasive type carries its own designation-usually a combination of a letter and a number. These designations vary by manufacturer. Zirconia alumina is another family of abrasives, each one made from a different percentage of aluminum oxide and zirconium oxide. The combination results in a tough, durable abrasive that works well in rough grinding applications, such as cut-off operations, on a broad range of steels and steel alloys. As with aluminum oxide, there are several different types of zirconia alumina from which to choose. Silicon carbide is an abrasive used for grinding gray iron, chilled iron, brass, soft bronze and aluminum, as well as stone, rubber and other non-ferrous materials.
Ceramic aluminum oxide is the newest major development in abrasives. This is a high-purity grain manufactured in a gel sintering process. The result is an abrasive with the ability to fracture at a controlled rate at the sub-micron level, constantly creating thousands of new cutting points. This abrasive is exceptionally hard and strong. It is primarily used for precision grinding in demanding applications on steels and alloys that are the most difficult to grind. The abrasive is normally blended in various percentages with other abrasives to optimize its performance for different applications and materials. Once the grain is known, the next question relates to grit size. Every grinding wheel has a number designating this characteristic. Grit size is the size of individual abrasive grains in the wheel. It corresponds to the number of openings per linear inch in the final screen size used to size the grain. In other words, higher numbers translate to smaller openings in the screen the grains pass through. Lower numbers (such as 10, 16 or 24) denote a wheel with coarse grain. The coarser the grain, the larger the size of the material removed. Coarse grains are used for rapid stock removal where finish is not important. Higher numbers (such as 70, 100 and 180) are fine grit wheels. They are suitable for imparting fine finishes, for small areas of contact, and for use with hard, brittle materials.
Buying Bonds
To allow the abrasive in the wheel to cut efficiently, the wheel must contain the proper bond. The bond is the material that holds the abrasive grains together so they can cut effectively. The bond must also wear away as the abrasive grains wear and are expelled so new sharp grains are exposed. There are three principal types of bonds used in conventional grinding wheels. Each type is capable of giving distinct characteristics to the grinding action of the wheel. The type of bond selected depends on such factors as the wheel operating speed, the type of grinding operation, the precision required and the material to be ground. Most grinding wheels are made with vitrified bonds, which consist of a mixture of carefully selected clays. At the high temperatures produced in the kilns where grinding wheels are made, the clays and the abrasive grain fuse into a molten glass condition. During cooling, the glass forms a span that attaches each grain to its neighbor and supports the grains while they grind. Grinding wheels made with vitrified bonds are very rigid, strong and porous. They remove stock material at high rates and grind to precise requirements. They are not affected by water, acid, oils or variations in temperature. Vitrified bonds are very hard, but at the same time they are brittle like glass. They are broken down by the pressure of grinding. Some bonds are made of organic substances. These bonds soften under the heat of grinding. The most common organic bond type is the resinoid bond, which is made from synthetic resin. Wheels with resinoid bonds are good choices for applications that require rapid stock removal, as well as those where better finishes are needed. They are designed to operate at higher speeds, and they are often used for wheels in fabrication shops, foundries, billet shops, and for saw sharpening and gumming. Another type of organic bond is rubber. Wheels made with rubber bonds offer a smooth grinding action. Rubber bonds are often found in wheels used where a high quality of finish is required, such as ball bearing and roller bearing races. They are also frequently used for cut-off wheels where burr and burn must be held to a minimum. The strength of a bond is designated in the grade of the grinding wheel. The bond is said to have a hard grade if the spans between each abrasive grain are very strong and retain the grains well against the
grinding forces tending to pry them loose. A wheel is said to have a soft grade if only a small force is needed to release the grains. It is the relative amount of bond in the wheel that determines its grade or hardness. Hard grade wheels are used for longer wheel life, for jobs on high-horsepower machines, and for jobs with small or narrow areas of contact. Soft grade wheels are used for rapid stock removal, for jobs with large areas of contact, and for hard materials such as tool steels and carbides.
Wheel Shapes
The wheel itself comes in a variety of shapes. The product typically pictured when one thinks of a grinding wheel is the straight wheel. The grinding face—the part of the wheel that addresses the work —is on the periphery of a straight wheel. A common variation of the straight wheel design is the recessed wheel, so called because the center of the wheel is recessed to allow it to fit on a machine spindle flange assembly. On some wheels, the cutting face is on the side of the wheel. These wheels are usually named for their distinctive shapes, as in cylinder wheels, cup wheels and dish wheels. Sometimes bonded abrasive sections of various shapes are assembled to form a continuous or intermittent side grinding wheel. These products are called segments. Wheels with cutting faces on their sides are often used to grind the teeth of cutting tools and other hard-to-reach surfaces. Mounted wheels are small grinding wheels with special shapes, such as cones or plugs, that are permanently mounted on a steel mandrel. They are used for a variety of off-hand and precision internal grinding jobs.
Tying It All Together
A number of factors must be considered in order to select the best grinding wheel for the job at hand. The first consideration is the material to be ground. This determines the kind of abrasive you will need in the wheel. For example, aluminum oxide or zirconia alumina should be used for grinding steels and steel alloys. For grinding cast iron, non-ferrous metals and non-metallic materials, select a silicon carbide abrasive. Hard, brittle materials generally require a wheel with a fine grit size and a softer grade. Hard materials resist the penetration of abrasive grains and cause them to dull quickly. Therefore, the combination of finer grit and softer grade lets abrasive grains break away as they become dull, exposing fresh, sharp cutting points. On the other hand, wheels with the coarse grit and hard grade should be chosen for materials that are soft, ductile and easily penetrated. The amount of stock to be removed is also a consideration. Coarser grits give rapid stock removal since they are capable of greater penetration and heavier cuts. However, if the work material is hard to penetrate, a slightly finer grit wheel will cut faster since there are more cutting points to do the work. Wheels with vitrified bonds provide fast cutting. Resin, rubber or shellac bonds should be chosen if a smaller amount of stock is to be removed, or if the finish requirements are higher. Another factor that affects the choice of wheel bond is the wheel speed in operation. Usually vitrified wheels are used at speeds less than 6,500 surface feet per minute. At higher speeds, the vitrified bond may break. Organic bond wheels are generally the choice between 6,500 and 9,500 surface feet per minute. Working at higher speeds usually requires specially designed wheels for high speed grinding. In any case, do not exceed the safe operating speed shown on the wheel or its blotter. This might be
specified in either rpm or sfm. The next factor to consider is the area of grinding contact between the wheel and the workpiece. For a broad area of contact, use a wheel with coarser grit and softer grade. This ensures a free, cool cutting action under the heavier load imposed by the size of the surface to be ground. Smaller areas of grinding contact require wheels with finer grits and harder grades to withstand the greater unit pressure. Next, consider the severity of the grinding action. This is defined as the pressure under which the grinding wheel and the workpiece are brought and held together. Some abrasives have been designed to withstand severe grinding conditions when grinding steel and steel alloys. Grinding machine horsepower must also be considered. In general, harder grade wheels should be used on machines with higher horsepower. If horsepower is less than wheel diameter, a softer grade wheel should be used. If horsepower is greater than wheel diameter, choose a harder grade wheel.
Care And Feeding
Grinding wheels must be handled, mounted and used with the right amount of precaution and protection. They should always be stored so they are protected from banging and gouging. The storage room should not be subjected to extreme variations in temperature and humidity because these can damage the bonds in some wheels. Immediately after unpacking, all new wheels should be closely inspected to be sure they have not been damaged in transit. All used wheels returned to the storage room should also be inspected. Wheels should be handled carefully to avoid dropping and bumping, since this may lead to damage or cracks. Wheels should be carried to the job, not rolled. If the wheel is too heavy to be carried safely by hand, use a hand truck, wagon or forklift truck with cushioning provided to avoid damage. Before mounting a vitrified wheel, ring test it as explained in the American National Standards Institute's B7.1 Safety Code for the Use, Care and Protection of Grinding Wheels. The ring test is designed to detect any cracks in a wheel. Never use a cracked wheel. A wise precaution is to be sure the spindle rpm of the machine you're using doesn't exceed the maximum safe speed of the grinding wheel. Always use a wheel with a center hole size that fits snugly yet freely on the spindle without forcing it. Never attempt to alter the center hole. Use a matched pair of clean, recessed flanges at least one-third the diameter of the wheel. Flange bearing surfaces must be flat and free of any burrs or dirt buildup. Tighten the spindle nut only enough to hold the wheel firmly without over-tightening. If mounting a directional wheel, look for the arrow marked on the wheel itself and be sure it points in the direction of spindle rotation. Always make sure that all wheel and machine guards are in place, and that all covers are tightly closed before operating the machine. After the wheel is securely mounted and the guards are in place, turn on the machine, step back out of the way and let it run for at least one minute at operating speed before starting to grind. Grind only on the face of a straight wheel. Grind only on the side of a cylinder, cup or segment wheel. Make grinding contact gently, without bumping or gouging. Never force grinding so that the motor slows noticeably or the work gets hot. The machine ampmeter can be a good indicator of correct performance.
If a wheel breaks during use, make a careful inspection of the machine to be sure that protective hoods and guards have not been damaged. Also, check the flanges, spindle and mounting nuts to be sure they are not bent, sprung or otherwise damaged.
System Analysis
The grinding wheel is one component in an engineered system consisting of wheel, machine tool, work material and operational factors. Each factor affects all the others. Accordingly, the shop that wants to optimize grinding performance will choose the grinding wheel best suited to all of these other components of the process. About the author: Joe Sullivan is senior product manager for Norton Company, Worcester, Massachusetts.
What Are Superabrasives?
Click Image to Enlarge
These CBN wheels for double-disc grinding are used on hard-to-grind materials in gear, pump, bearing and automotive component manufacturing. Superabrasives make up a special category of bonded abrasives designed for grinding the hardest, most challenging work materials. Because carbides, high speed steels, PCD, PCBN, ceramics and some other materials used to make cutting tools can be nearly as hard as conventional abrasives, the job of sharpening them falls to a special class of abrasives-diamond and the CBN, the superabrasives. These materials offer extreme hardness, but they are more expensive than conventional abrasives (silicon carbide and aluminum oxide). Therefore, superabrasive grinding wheels have a different construction than conventional abrasive wheels. Where a conventional abrasive product is made up of abrasive all the way through, superabrasive wheels have abrasive on the cutting edge of the wheel that is bonded to a core material, which forms the shape of the wheel and contributes to the grinding action. Superabrasive wheels are supplied in the same standard grit range as conventional wheels (typically 46 through 2,000 grit). Like other types of wheels, they can be made in a range of grades and concentrations (the amount of diamond in the bond) to fit the operation. There are four types of bond used in superabrasive wheels. Resinoid bond wheels are exceptionally fast and cool cutting. They are well-suited to sharpening multi-tooth cutters and reamers, and for all precision grinding operations. Resin is the "workhorse" bond, most commonly used and most forgiving. Vitrified bond wheels combine fast cutting with a resistance to wear. They are often used in
high-volume production operations. Metal bond wheels are used for grinding and cutting non-metallic materials, such as stone, reinforced plastics and semiconductor materials that cannot be machined by other cutting tools. Single-layer plated wheels are used when the operation requires both fast stock removal and the generation of a complex form.
Class Objectives • Understand the factors that affect grinding material selection. • List the most important characteristics of abrasive grains. • Cite different ways abrasive grains may be classified. • Describe the defining characteristics of aluminum oxide. • Describe the defining characteristics of zirconia alumina. • Describe the defining characteristics of silicon carbide. • Describe the defining characteristics of ceramic aluminum oxide. • Describe the defining characteristics of diamond. • Describe the defining characteristics of cubic boron nitride. • Describe the characteristics of bonds. • Explain what determines wheel grade. • Name the four types of wheel bonds. • Describe the defining characteristics of vitrified bonds. • Describe the defining characteristics of organic bonds. • Describe the characteristics of superabrasive bonds. • List the categories on the standard abrasive wheel marking chart. • List the categories on the superabrasive wheel marking chart.
Class Vocabulary alumina The natural form of aluminum oxide. aluminum oxide An abrasive made by fusing bauxite, iron, and coke that is widely used to grind ferrous materials. The natural form is called corundum. American National Standards Institute A private, non-profit organization that administers and coordinates voluntary standards and systems. arc furnace A heating unit that uses electric arcs between carbon electrodes to melt steel and manufacture abrasives. Also called an electric arc furnace. bauxite A form of aluminum oxide that contains several impurities. bond The "glue" or adhesive material that holds abrasive grains together in a grinding wheel. Bonds may be vitrified, organic, metal, or electroplated. carbide A compound developed by the combination of carbon with usually tungsten, titanium, or tantalum that is used in metal cutting tools for its hardness and wear resistance. carbon steel The basic type of steel, which contains less than 3% of elements other than iron and carbon. cast iron A metal consisting of iron, over 2.11% carbon, and 1 to 3% silicon. Cast irons will normally contain trace amounts of other elements. ceramic aluminum oxide An exceptionally hard, strong, sharp abrasive made from a process in which alumina gel is dried and crushed. Ceramic aluminum oxide has the ability to refracture at the sub-micron level. chemical vapor deposition A method of manufacturing diamonds that uses heat and radio waves or microwaves to break a carbon-rich gas into pieces that reassemble themselves into diamond. coke The carbon-containing residue remaining from coal distillation. conventional abrasive One of several inexpensive abrasives of varying hardnesses commonly used in industry for material removal. cubic boron nitride The second-hardest substance after diamond. Cubic boron nitride (CBN) is manufactured in a highheat, high-pressure sintering process. diamond The hardest known substance. Made from carbon, diamond is both a naturally occurring and manufactured abrasive. electroplated bond A superabrasive bond accomplished by immersing a metal wheel in an electrically charged chemical bath that contains metal particles. ferrous metal A metal containing iron. friability
The ability of abrasive grains to fracture and self-sharpen under stress.
grade The strength of the bond in an abrasive wheel. graphite A soft, black form of carbon. Graphite is used to manufacture diamonds. hardness The ability of a material to resist penetration and scratching. hexagonal boron nitride A boron-nitrogen compound that has a six-sided crystal structure. high-speed steel A tool steel used to machine metals at high cutting speeds. High-speed steel stays hard at high temperatures and resists abrasion. iron The fourth most abundant earth element. Iron is alloyed with carbon to make steel. kiln An oven or furnace used for heating or drying. lapping A precision abrasion process used to bring a surface to a desired state of finish or dimensional tolerance by removing an extremely small amount of material. manufactured abrasive A material of extreme hardness created through chemical and/or physical processes that is used to shape other materials by a grinding or abrading action. manufactured diamond The manufactured form of a carbon mineral that is the hardest substance known to man. It is manufactured through a highheat, high-pressure process. metal bond A bonding material used most often with superabrasive grinding wheels. micron A measurement equal to one twenty-fifth of a thousandth of an inch (0.00004 inch). natural abrasive A hard material found in the earth that is used to shape other materials by grinding or abrading. Sand and quartz are both natural abrasives. natural diamond The mined form of a carbon mineral that is the hardest substance known to man. nonferrous A material that does not contain iron. Aluminum, copper, and zinc are nonferrous metals. organic bond An abrasive bonding material that contains carbon. Organic bonds tend to soften with heating. porosity The relative number of openings or voids in a material. porous Having many openings or voids. post A structural beam that connects abrasive grains in a bonded abrasive grinding wheel. resinoid bond An organic bond made of synthetic resin. roll Long, cylindrical metal parts used in mills that make paper, sheet metal, and other similar products. rubber bond An organic bond made of natural or synthetic rubber. shellac bond An organic bond made of shellac, a material secreted on the bark of trees by an insect that has ingested tree sap. silicon carbide A hard, brittle abrasive made by firing a mixture of quartz, petroleum coke, and small amounts of sawdust and salt in an electric furnace. Silicon carbide is known for its green color. sintering
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Straight Wheel Grinding wheels consist of abrasive grains bonded together by a matrix of resins, epoxy, rubber, metal, and vitrified glass materials. Straight wheels have a simple, flat disc shape without any recesses, flaring or cups. ANSI B74.2 Type 1 wheels fall under this group. Type 1A1, 1A8 are designations for straight superabrasive wheels with a straight face and no recess. 1A1R wheels are recessed for cut-off or slot cutting applications. 1A8, 1B1, 1E1, 1EE1, 1F1, 1FF1, 1V1, 1V1P are straight superabrasive wheels with modified faces (beveled, included angle or radius). Blank / Custom Blank or custom wheels are designed for customization to a user's shape requirements. Cone / Plug Small bonded abrasives wheel with a cone, cylinder or bullet shape that is mounted on a pin or mandrel for portable grinder applications. ANSI B74.2 Types 16, 17, 17R, 18, 18R, and 19. Type 16 - Cone wheels with a curved side and a nose radius
· Type 17, 17R - Cone wheels with straight sides and optionally a nose radius · Type 18, 18R - Plug wheels with a cylindrical shape and either a square or curved grinding end · Type 19 - Combination cone and plug shaped wheels Cylinder Cylinder wheels are long wheels with a simple, can shape without any recesses or cups. The length of the wheel is equal or greater than the thickness of the wheel. ANSI B74.2 Type 2 wheels fall under this group. Cylinder wheels are mounted (bolted or cemented) to a backing plate, which drives the wheel. Depressed Center Grinding wheels with a depressed center, which helps keep the mounting hardware out of the grinding process. ANSI type 27, 28 and 29 wheels fall under this category. ANSI type 27 wheels have a flat configuration with a depressed center. ANSI type 29 wheels fold back away from the workpiece and wheel center while ANSI type 28 wheels project out in front of the wheel center toward the workpiece. Depressed center wheels are applied is rough offhand grinding or snagging of castings, weld beads, flash or parting lines or defects in metal parts. Dish Wheel Wheels with a dish or saucer shape such as ANSI type 12 wheels. Types 12V9, 4A2P, 12A2 and 15V9 are examples of superabrasive dish shapes. Flaring Cup Cups have a cup or bowl shape. Type 11 wheels are often called “flaring cups” since the sides flare out. Types 11V9, 11A2 and 12A2 are examples of superabrasive flaring cup shapes. Mounted Point / Abrasive Burr Very small bonded abrasives or superabrasive wheels with a round ball, point, cone, cylinder or bullet shape that are mounted on a pin or mandrel for portable die grinder and deburring applications. Types DW, IG, IGJ, IGA, IGI and IGR are examples of superabrasive mounted point shapes.
Recessed / Relieved Recessed wheels having an ANSI 5 or 11 shape fall under this category. Type 5 wheels are only recessed on one side. Type 7 wheels are recessed on both sides. Ring / Disc Wheel Ring wheels have a donut or toroid shape. Ring or disc grinding wheels are mounted (bolted or cemented) to a backing plate, which drives the wheel. Superabrasive type 2A2 wheels fall into this category. Conventional bonded abrasive type 35, 36 and 37 fit into this category. Straight Cup Cups have a cup, bowl or double cup shape. ANSI type 6 wheel are referred to as straight cups, since they have a cylindrical configuration. Types 6A2, 6A9, 6A2C and 6A2H are examples of superabrasive straight cup shapes. ANSI type 9 or superabrasive type 9A1 wheels have a double cup shape. Tapered Body Tapered body wheels have a thicker cross section at the bore, which becomes thinner or tapers toward the outer diameter. ANSI Type 3 or 4 wheels fall under this group. Superabrasive types 14A1and 3A1 wheels fall into this category. Specialty / Other Other specialty, proprietary or patented abrasive or abrasive product. Search Logic: All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches. Superabrasive Wheel?
Superabrasives and diamond tools consist of grinding wheels, wheel dressers, single point tools and other products utilizing diamond or cubic boron nitride (CBN) abrasive grain. Search Logic: "Required" and "Must Not Have" criteria limit returned matches as specified. Products with optional attributes will be returned for either choice. Outer Diameter (OD): The OD is the outer diameter of the abrasive product. Search Logic: User may specify either, both, or neither of the "At Least" and "No More Than" values. Products returned as matches will meet all specified criteria. Bore ID / Shank Diameter: The bore is the inner diameter of the center mount of the abrasive product. The bore is used to mount or hold the abrasive on a spindle or mandrel. The shank diameter is the diameter of the integral shank, pin, shaft or mandrel on mounted points or wheels. Search Logic: User may specify either, both, or neither of the "At Least" and "No More Than" values. Products returned as matches will meet all specified criteria. Thickness: The wheel face thickness or the overall thickness of the abrasive products such as stones, segments, hand pads, etc. Search Logic: User may specify either, both, or neither of the "At Least" and "No More Than" values. Products returned as matches will meet all specified criteria. Abrasive Grain Type
Abrasive Grain Type:
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Aluminum Oxide Aluminum oxide is the most common industrial mineral in use today. Fused aluminum oxide is produced synthetically by melting bauxite and additive in an arc furnace to form a fused aluminum oxide ingots, which are later crushed and sized. Fused aluminum oxide is also produced synthetically by chemically purifying The various types of fused aluminum oxides are distinguished by the levels of chemical impurities remaining in the fused mineral. Titanium and chromium oxides are typical additives. Other techniques to make industrial abrasive start with treating bauxite ore with a sol gel process to create alumina that is sintered to produce with an extremely fine crystalline structure typical of the sol gel or Seeded Gel products available by Saint Gobain Abrasives. Fused aluminum oxide is available in several variations depending on composition and processing such as white (high purity), brown or regular (titanium oxide modified) and pink (chromium oxide additions). Titanium oxide additions can toughen the abrasive and enable heat treating process, which changes brown aluminum oxide to a blue colored grain as TiO2 precipitates form. Aluminum oxide abrasives are also produced with chemical precursors and precipitation, calcination and/or sintering processes. Calcined or platelet aluminas as used in fine grit or polishing applications. Sol-gel aluminum oxide is produced in using chemical ceramic technology, but this abrasive has very high performance and is usually referred to as Ceramic abrasive grain to distinguish the grain from lower performing fused aluminum oxide. Aluminum oxide occurs naturally in the form of the mineral corundum, but the mineral is not used as a commercial abrasive except as a component of emery. Ceramic (e.g., Norton SG®, Norton Quantum®) Ceramic abrasives typically consist of aluminum oxide with or without additional modifiers produced using a sol-gel and sintering process. The ceramic processing route results in a hard, dense abrasive with an extremely fine crystal size and outstanding grinding performance on a variety of workpiece materials. Norton SG® and Norton Quantum® are examples of ceramic alumina grain manufactured by the Saint-Gobain Group. The patented alumina seeding process used in manufacturing Norton SG® abrasive grain produces a sub-micron crystal structure resulting in superior performance. Silicon Carbide
Silicon carbide is a synthetic abrasive first developed in the late 1800s. SiC is harder than aluminum oxide, but more friable than fused aluminum oxide grains. Silicon carbide is typically applied to nonferrous applications (brass, aluminum, titanium). The high solubility of carbon and silicon in iron would result in a reaction of silicon carbide with the iron base alloy and poor grinding performance. Levels and types of impurities distinguish the green and black forms of silicon carbide. The sharp and easily fractured abrasive grains for abrading other non-metals such as the stone, glass, wood, and leather. SiC, like diamond, is susceptible to oxidation at higher temperatures. Zirconia (e.g., Norzon®) Alumina-zirconia abrasive grain consists of a fused alloy of aluminum oxide and zirconium oxide. NorZon® is widely used variation proprietary to Norton Company, which consisting of a fused and quenched eutectic mixture of aluminum oxide and zirconium oxide. The resulting fine structure and higher hardness contributes to improved grinding performance on stainless steel, titanium and other exotic metals. Superabrasive - Diamond Synthetic diamond is produced synthetically in a high temperature, high pressure process anvil press. Diamond is superabrasive grain with the highest known hardness and a cubic crystal structure. Diamond is used for grinding nonferrous metals, ceramics, glass, stone, and building materials. Diamond is not useful in grinding steel or ferrous alloys because carbon or diamond readily dissolves or reacts with iron. Diamond pastes are useful in ferrous polishing or lapping applications where heat and reactivity are not a factor. Diamond is susceptible to oxidation at higher temperatures Superabrasive - CBN Cubic boron nitride (CBN) is superabrasive grain with hardness second to diamond and a cubic crystal structure. CBN provide super grinding performance on carbon and alloy steel. Diamond is not useful in grinding steel or ferrous alloys because carbon or diamond readily dissolves or reacts with iron. CBN is produced synthetically in a high temperature, high pressure process anvil press a process similar to synthetic diamond production. Tungsten Carbide Crushed tungsten carbide grit is utilized in metal bonded products for abrasion of tough materials such as composites, fiberglass, reinforced plastics, rubber and other specialized materials. Other
Other specialty, proprietary or patented abrasive grain, grit or abrasive material. Search Logic: All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches. Metal Clad / Armored? Abrasive grain with a metal layer or coating. Certain superabrasive products utilize metal clad grain to dissipate heat or enhance bonding. Search Logic: "Required" and "Must Not Have" criteria limit returned matches as specified. Products with optional attributes will be returned for either choice. Grit Size
Grit / Micron Size: Applies to products using abrasive grains held in a matrix or bonded to a surface such as coated abrasives, MSL superabrasives, vitrified grinding wheels, dressing sticks, honing stones or grit dressers. Grit sizes are based on ANSI, FEPA, JIS or proprietary grading system standards. Grading system standards define a grit size through specified upper and lower limits at certain points in the size distribution. Search Logic: User may specify either, both, or neither of the "At Least" and "No More Than" values. Products returned as matches will meet all specified criteria. Grading / Grit System:
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ANSI - Bonded American or U.S. grading or grit size standards for abrasive grains used in bonded abrasives or grinding wheels. FEPA - F European grading or grit size standards for abrasive grains used in bonded abrasives or grinding wheels. JIS Japanese grading or grit size standards for abrasive grains. Micron Graded Very fine abrasive grain graded to micron size ranges usually based an average particle size. Specialty / Other Other unlisted, proprietary, or specialized grading or grit system. Search Logic: Products with the selected attribute will be returned as matches. Leaving or selecting "No Preference" will not limit the search criteria for this question; products with all attribute options will be returned as matches. Applications
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Material Removal / Roughing (Coarse Grits) Typically coarse grit abrasive products designed for heavy cutting or stock removal applications with rougher commercial finish compared to finer grit wheels. Vitrified or bonded abrasive wheels with 46 grit and coarser grain and 100S grit superabrasive wheels would fall into this category. Intermediate Cut & Finish (Medium Grits) Medium or medium fine grit products are typically used for moderate stock removal combined with a better finish compared to coarser grits. Vitrified or bonded abrasive wheels with in the 54 to 80 grit grain size and 120 grit superabrasive wheels would fall into this category. Finishing / Light Cutting (Fine Grits) Fine grit abrasive products designed or suitable finishing with light cutting or stock removal. Vitrified or bonded abrasive wheels with in the 100 to 120 grit grain size and 150 grit superabrasive wheels would fall into this category. Corner Holding / Finish Generation (Very Fine Grits) Very fine to ultrafine abrasive products are used to improve finish and provide good corner holding characteristics. Ultrafine grit may be used for honing type applications. Vitrified or bonded abrasive wheels with 150 grit or finer grain and 180 grit superabrasive wheels would fall into this category. Cleaning / Surface Prep Abrasive products such as non-woven wheels suitable for cleaning, stripping coatings, descaling, deburring or other surface preparation applications. Bench / Pedestal Abrasive product designed for use on bench or back stand grinders or sanders with offhand (handheld) presentation of the parts to the abrasive.
Cylindrical / Centerless Grinding between centers of shafts, threaded shafts, large rolls, cams or similar components.
Dry Grinding Abrasive products designed or suitable for dry grinding applications. Form / Gear Grinding Form, profile, gear, and other processes where the surface of the grinding wheel is shaped by dressing to create a specific profile. By dressing an inverse profile of the desired component surface on to a grinding wheel, complex sequencing of multiple steps can be avoided. Form grinding is also possible with coated abrasives and nonwoven products using specialized accessories. Internal / Bores Internal grinding utilizes smaller diameter wheels or abrasive products for grinding or finishing the surface on the inner diameter of a part. Portable Grinder / Handheld Abrasive product designed for use on portable or handheld grinders or sanders such as weld grinding on a large fabrication. Surface / Creepfeed Grinding Abrasive products designed or suitable for Blanchard, surface or creepfeed grinding applications. Toolroom / Sharpening
Abrasive products designed or suitable for toolroom or precision grinding applications Wet Grinding Waterproof abrasive products designed or suitable for grinding using a water or water-oil coolant mixture. Specialty / Other Abrasive products designed or suitable for other specialty, proprietary or patented applications. Search Logic: Products with the selected attribute will be returned as matches. Leaving or selecting "No Preference" will not limit the search criteria for this question; products with all attribute options will be returned as matches. Product / Materials Abraded:
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Metalworking Abrasive products designed for metal grinding or finishing applications. Automotive Abrasive products designed or suitable for automotive applications such as part or weld grinding and paint sanding. Ceramics / Glass
Abrasive products designed or suitable for ceramics and glass grinding or finishing. MRO / Construction Abrasive products designed or suitable for cutting, grinding or finishing in maintenance & repair operations (MRO) such as the grinding of repair welds. Ophthalmic / Optical Abrasive products designed or suitable for cutting, grinding or finishing applications in optical lens or component fabrication as well as for eyeglass or ophthalmic production. Plastics / Composites Abrasive products designed or suitable for cutting, grinding or finishing plastics or composite materials. Semiconductors / Electronics Abrasives wheels and blades designed for semiconductors or electronics such as back grinding, finishing, CMP pad dressing, IC die cutting, wafer slicing or other electronics applications. Specialty / Other Abrasive products designed or suitable for cutting, grinding or finishing other unlisted specialty or proprietary materials. Search Logic: All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches. Rotary Speed: The maximum rotary speed or speed range recommended by the supplier.
Search Logic: User may specify either, both, or neither of the "At Least" and "No More Than" values. Products returned as matches will meet all specified criteria. Bond Type
Bond Type:
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Metal Metal bond between the abrasive grains and between the grains a metal substrate. Metal bond systems are used mainly for superabrasive or tungsten carbide grit products. Three metal bond types are sintered, MSL and electroplated metal bond systems. Sintered metal bond systems are used when a thicker layer of superabrasive is required. Metal single layer (MSL) wheels consists of a specialized braze layer that forms a single layer of superabrasive and bond. The electroplated bond system is used to produce fine grit superabrasive products. Resin / Plastic Bonded abrasive product with a resin, resinoid or plastic bond system between the abrasive grains. Rubber Bonded abrasive product with a rubber or elastomer bond system between the abrasive grains. Shellac Bonded abrasive product with a shellac bond system between the abrasive grains.
Silicate / Oxychloride Bonded abrasive product with a bond system using a silicate, magnesium oxychloride, magnesite or Sorel cement. These low strength bonds keep heat generation to a minimum, but may lack the life and durability of vitrified or resin bonded wheels. The chloride in the oxychloride may provide a grinding aid action. Vitrified Bonded abrasive product with a vitrified or glass bond system between the abrasive grains. Other Other specialty, proprietary or patented bond type. Search Logic: All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches. Mounting
Mounting:
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Bore / Center Mount Central hole or bore for mandrel, arbor, spindle or shaft mounting. Integral Mandrel (Mounted)
Abrasive tool is supplied as mounted onto an integral mandrel, pin, arbor or shaft. Plate Mounted Abrasive wheel is mounted on a Quick Change Abrasive product or disc designed for mounting using a quick change mechanism such as Norton's SpeedLocTM. Quill Mount Grinding wheel designed for mounting using a quill. Specialty / Other Other specialty, proprietary or patented mounting method. Search Logic: All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches. Features
Features:
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Open Structure / Low Concentration
1. Bonded Abrasives - Open Structure 2. Coated Abrasives - Open Coat 3. Superabrasives - Low Concentration
Angle / Double Bevel (E Face) Abrasive wheel face having a pointed, "Vee" or double beveled shape for threading or similar applications. Radius Face (F Face) Radius face wheels have a face that is rounded such as type 1F1 shapes. Tapered / Fluting (V, B Face) Tapered face wheels have a face that is angled back such as type 1V1P shapes. Tapered face wheels are used for fluting applications. Specialty / Other Other specialty, proprietary or patented features. Search Logic: All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be
returned as matches. Part Numbers for Grinding Wheels Part # 6NX10 6NX30 FT-G3401 FT-G3501 FT-G3005 FT-G2105 FT-G3201 6NX57 6NX21 6NW97 More >> Find Companies by Name View Grinding Wheels Datasheets View Suppliers by State Alaska Idaho Alabama Illinois Arkansas Indiana Arizona Kansas California Kentucky Colorado Louisiana Connecticut Massachusetts District of Columbia Maryland Delaware Maine Florida Michigan Georgia Minnesota Hawaii Missouri Iowa Mississippi Related Keywords diamond cutting wheel, mounted point, wheel block, bench grinder wheel, depressed center wheel, diamond cup wheel, dragline bucket type, aluminum oxide wheel, custom grinding wheel, diamond crystal structure, recessed grinding wheel, synthetic diamond, alloy wheel repair, cheap english wheel, cheap wheel english, cone wheel, cup grinding wheel, diamond dressing wheel, dunlop wheel Distributor Amazon Amazon Amazon Amazon Amazon Amazon Amazon Amazon Amazon Amazon Manufacturer Westward Westward Foredom Foredom Foredom Foredom Foredom Westward Westward Westward Product Category Description BISS Westward 6NX10 Grinding Wheel, 6 In BISS Westward 6NX30 Grinding Wheel, 8 In BISS Foredom 80 Grit 1/2" OD Aluminum Oxide Red Grinding Stones BISS Foredom 80 Grit 1/2" OD Aluminum Oxide Red Grinding Stones BISS Foredom 80 Grit 5/8" OD Aluminum Oxide Red Grinding Stones (Pack of 5) BISS Foredom 120 Grit 1/2" OD Aluminum Oxide Red Grinding Stones (Pack of 5) BISS Foredom 80 Grit 5/8" OD Aluminum Oxide Red Grinding Stones BISS Westward 6NX57 Grinding Wheel, 14 In BISS Westward 6NX21 Grinding Wheel, 7 In BISS Westward 6NW97 Grinding Wheel, 6 In
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