Choosing The Right Grinding Wheel
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 variety 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 as well as 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 nonferrous materials.
Ceramic aluminum oxide is another 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 submicron 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.
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. These bonds 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.
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.
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.
These diamond metal bond wheels offer superior performance in round tool grinding.
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, nonferrous 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.
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 was a senior product manager for Norton Company, Worcester, Massachusetts.
What Are Superabrasives?
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 nonmetallic 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.
Silicon Carbide Grinding Wheel Dresser
CRATEX rubber-bonded silicon carbide dressing stick for grinding wheels is ideal tool for truing, dressing and shaping different types of grinding wheels including CRATEX rubberized abrasive wheels. It is a perfect solution to keep your grinding wheel flat, sharp, clean and running smoothly!
With this easy to use, efficient and long-lasting dresser you’ll enhance your grinding wheel cutting and finishing performances. It’s simply a MUST for everyone who continuously uses a bench grinder.
Use CRATEX cleaning abrasive sticks and minimal effort and your grinding wheel will be in a top-notch form in just a few minutes. Simply choose the dressing wheel shape, grit and length and before you know it, your order will be on the way!
Recommended for CRATEX Large Grinding Wheels : Dressing Stick Size: 6” x 1/2” x 1/2”
Click the icon to jump to the desired section
What is Grinding Wheels Dressing
CRATEX Dressing Stick
What Is The Difference Between Dressing And Truing?
Grinding wheels are tools used most often for grinding (abrasive cutting) operations. In our article dedicated to grinding wheels we already explained that grinding wheels are designed as self-sharpening tools, which means that the grinding process itself sharpens the wheel every time it’s used. Small abrasive cutting grains of the wheel become dull during the grinding process and break away from the bonding material, leaving the sharp grains exposed. However, this awesome self-sharpening ability is not quite enough, since the work material can cause it to load up, so it is necessary to occasionally dress or true the wheel to achieve satisfying results. If the wheels are not maintained, increased cutting forces and the created heat can cause damage to the surface finish and wheel breakage. Dressing is not so much important for rough grinding wheels, but you’ll need to always have a true, flat face on your wheel in case you’re doing some precision grinding.
Here’s where the grinding wheel dresser steps in. It is a handy tool used to remove the top layer of a grinding wheel in the purpose of:
- Truing it and making it concentric, which will minimize vibrations and improve the quality of the finishing operations. Loaded or clogged areas on the wheel will cause it to lose its roundness, and the loss of the roundness will eventually cause excessive vibrations of the bench grinder. The reason why the wheel loses its shape is because the clogged areas wear off at a different rate from the less loaded areas;
- Exposing fresh abrasive grains, which will enhance the cutting action. Dull grains of the wheels with extremely hard bond will usually remain in the wheel;
- Cleaning the pores between the abrasive grains, which get filled with workpiece fragments. This happens in case the workpiece has a softer grade than the one the wheel is designed for. In that case, the grains won’t break away in time and the workpiece parts will get stuck between them.
With dressing, the wheel will be good as new and ready for renewed grinding action!
Grinding wheel dressers can be broadly divided in following categories:
- Dressing rolls and rotary tools – these dressers have rolls or wheels that are coated with diamonds;
- Dressing spindles. spindle-mounted tools that usually come with an integral brake and drive;
- Dressing sticks – or dressing blocks are made of bonded abrasives;
- Impregnated or grit dressing tools – these have a whole layer of diamond or superabrasive grains bonded in the matrix, much more sharp points than an ordinary multi-point tool. These are used in the same way as multi-points tools, but they are designed to provide a superior finish;
- Single-point dressing tools – these have only one diamond or superabrasive grit bonded in the tip and can be various: single point tools should be mounted at a 10°-15° angle to the wheel centerline while the contact point should be slightly below the centerline. The tools should point in the direction of wheel travel;
- Multi-point or Cluster dressing tools – unlike the single-point ones, cluster dressers have several diamonds or superabrasives across the dresser surface. They can be wide enough to reach across the entire cutting surface of the grinding wheel and most of them are used for straight-face dressing. They came into use mostly because they’re more affordable (instead of one large diamond they have several smaller ones).
Grinding wheel dressers used most often on bench grinders are as follows:
These are dressing bonded abrasives shaped as a stick or a block. You’ll usually use dressing blocks made from the same abrasive type as the grinding wheel, but you’ll choose a stronger bonding agent. Typical abrasives used in grinding wheel dressing sticks are aluminum oxide and silicon carbide. For resin and vitrified bond diamond and cBN wheels you should choose a dressing stick that is one or two grit sizes finer than the abrasive in the wheel. For metal bond diamond choose a stick the same grit size or one grit size coarser than the wheel abrasive.
These are heavy-duty dressers with long handles, a row of hardened free running either star-shaped cutters or wavy discs, and little ‘legs’ that are designed to go behind the tool rest. Star dressers provide a more ‘open’ texture, which is perfect for rough grinding, and they are more suitable for larger (e.g. 12″) grinders. They are consumable items that are going to wear down, so you’ll need to change the discs after they do.
These dressers have a short handle and you can find two types. Either those with a single diamond embedded in their face, or those with a lot of small diamonds embedded in a wide surface. Diamond is the hardest superabrasive used for truing and dressing conventional and superabrasive grinding wheels. It’s ideal for fine finishing cutting tools as it gives the grinding wheel a smoother finish. Although diamond dressers might seem pricey initially, rest assured you’ll get your money’s worth, since diamond is extremely durable and therefore a long-lasting tool.
When it comes to CNC grinders, four types of dressers can be used for dressing their wheels.
This is a wheel made of either high-speed steel or tungsten carbide, which is pressed against the grinding wheel while spinning at the same speed as the wheel. The dresser profile is the mirror image of the desired grinding wheel profile and cannot be adjusted, only replaced by a different profile.
This would be a crush roll which is coated with diamond grains. Diamond grains give them an advantage over regular crush rolls, because they wear more slowly.
These have a metal blade that has a single diamond embedded in the tip. A CNC program for dressing the wheel controls the wheel’s profile and is responsible for moving the dresser across the wheel’s surface.
These are sometimes called ‘pizza cutters’. A disc made of material (usually a diamond) is attached to the edge, and the grinding wheel’s profile is controlled by the CNC program used to wheel dressing as well.
CRATEX silicon carbide grinding wheel dresser dresser is a perfect tool for dressing and truingdifferent kinds of grinding wheels including all rubber-bonded abrasive wheels. Thanks to its shape, fast cutting abrasive with a hardened bond, it’s an efficient, easy to handle and a long-lasting dressing stick that will help you achieve maximum performance from all your CRATEX rubberized abrasive wheels.
Selecting the appropriate dressing stick will depend on the size, type, speed, grit size and specification of the wheel, and of course, the workpiece material. A good advice would be to test several sticks to find the best possible solution for your needs.
RECOMMENDED: Check out CRATEX Mini Test Block Kit No.128B (shipping and handling included in the price)
Order Mini Block Kit No. 128B SKU: Q128B Block Kit
Dressing sticks are used for dressing and truing bench and pedestal grinder wheels. You’ll only need your hand and a dressing stick to perform the dressing which is done by moving the stick back and forth against the wheel face. In case the movement is fast, so will be the metal removal, which will cause rougher finishes on the workpiece. If the movement is slower, the grinding wheel face will be smoother, there will be less metal removal and the surface finish on the workpiece will be finer.
CRATEX dressing sticks are a perfect solution to keep your grinding wheel flat, sharp, clean and running smoothly! A MUST for everyone who continuously uses a bench grinder!
Order Square Sticks
Both dressing and truing must be conducted in the purpose of creating satisfactory work. Both operations remove material from the grinding wheel. While dressing relates to a surface finish maintenance, truing relates to the loss of form control due to the excessive edge wear.
Although sometimes together referred to as ‘conditioning’, they mean two different operations. Conventional grinding wheels that are inexpensive can be trued and dressed at the same time and the process can be repeated periodically. However, superabrasive grinding wheels, like CBN or diamond wheels, are a serious investment and require much more attention to dressing and truing separately.
Truing is done when a new wheel is installed and before it’s used for the first time and is necessary for precision grinding. The purpose of truing is to bring every point of the grinding surface concentric with the machine spindle (to establish concentricity) and to introduce a form (shape) into a wheel. No matter how precisely manufactured, there will be a slight gap between the wheel bore and the machine spindle. Even if the gap is one thousand of a millimeter, problems like chatter marks will occur if the wheel is not trued to the center of the spindle. Conventional grinding wheels can be trued easily with a diamond cutter that is harder than the wheel, while the superabrasives cannot be cut and must be ground to size. This is done by using a sintered diamond roller or by traversing a conventional grinding wheel. Many like to use a brake-controlled truing device called BCTD which turns more slowly and provides a more precise and controllable truing. After the truing process, the wheel surface is smooth and closed, and since there are no abrasive grits exposed, the wheel can’t perform cutting.
Dressing is the process that comes after truing (especially in the case of superabrasives) and it represents grinding wheel sharpening by exposing abrasive grits above the bond. In other words, removing small chips of workpiece lodged in the wheel surface or removing dull abrasives which returns the wheel to its original dimensions and provides crystal exposure. The wheel surface after dressing is open with grits exposed.
- AIR TOOLS
- Rubberized Abrasives
- MX Abrasives
- Regulating Wheels
- 2023 © Cratex
- Tel: 800-800-4077
- Fax: 760-942-4513
- Email: email@example.com
- Powered by IT Support San Diego | Design by San Diego SEO Expert
Types of Abrasives Used in Grinding Wheels
Posted June 12, 2022 by DXP Marketing. filed under Blog.
Where a saw uses a single layer of teeth to bite into a surface, grinders use abrasives with many fine grains that work together to cut. The material and needed finish will guide your choice of abrasive, but there are two basic types of abrasives used in grinding wheels: bonded and coated.
What is a Grinding Wheel?
A grinding wheel is made from fiberglass layers and abrasives bonded together. The bonded abrasives work as a grinding tool, allowing the operator to shape and refine materials. Grinding wheel uses include sharpening tools, getting metals ready for welding, and removing excess material.
Grinding Wheel Types
The shape and size of the wheel typically determine the grinding wheel’s uses and type. Grinding wheel types include,
- Straight grinding wheels – These are basic grinding wheels often found in home workshops where they are primarily used to sharpen tools.
- Large diameter grinding wheels – are larger versions of straight grinding wheels. The wheel’s large surface diameter makes them ideal for grinding round objects. The wheels are also used in the Oil and Thermal Spray Industry for OD grinding.
- Grinding cup wheel – is primarily used for polishing concert and stone. However, depending on the size of the abrasive grinding wheel, it can also be used to remove adhesive and paint from materials.
- Grinding dish wheel – Similar in appearance to a grinding cup wheel, these bonded abrasive wheels have a thinner edge that allows the tool to reach into narrow places a grinding cup wheel cannot access.
- Segmented grinding wheel – These abrasive grinding wheels have segmented sections instead of a continuous rim. The segmented bonded abrasives allow you to easily remove larger amounts of material without damaging its surface.
- Cutting face grinding wheel – is a precision tool that cuts through the material. Its best uses include shaping teeth on a saw, along with cutting tile and other materials.
When you are trying to decide on the type of grinding wheel, it’s a good idea to consider the application. For example, you don’t want to purchase a large diameter grinding wheel if you only want to sharpen your garden tools.
Bonded vs. Coated Abrasives
Grinding wheels are made from different types of abrasives. The type of abrasive helps determine the tool’s best uses. The classification of abrasives includes bonded, coated, and non-woven grits.
Bonded abrasives use a binder to fuse the material into the wheel shape. It can limit the type of grit used, but it is an effective method. Grinding wheels with bonded abrasives are durable and capable of taking on heavy-duty tasks. Coated abrasives are also durable, but the process is a little different. Grinding wheels with coated abrasives have an extra layer. The grit adheres to a belt, disc, roll, or sheet.
You can also find grinding wheels with non-woven abrasives. These grinding wheels use three-dimensional abrasives typically bonded to nylon fibers. It gives you a flexible and durable surface, ideal for use in more delicate jobs like removing paint without scratching the surface.
Coated Abrasives in Grinding Wheels
When talking about abrasives, coated abrasive typically refer to layered grits and grains over a surface. For example, coated abrasives are commonly affixed to belts, sheets, discs, and rolls. The cutting grains layer on top of the foundation material. An especially common type of coated abrasive would be sandpaper.
Bonded Abrasives in Grinding Wheels
With a grinding wheel, you will be using bonded abrasives. The grains are bonded together with a binding agent or resin to add support to the grinding surface while cutting. The type of grain, the spacing, and the bond material will determine what materials an abrasive can cut.
Check out the abrasive supplies on the DXP website for a broader selection and supplier list.
Common Types of Grinding Wheel Abrasive
Abrasives can be used to cut and finish a variety of materials ranging from high-carbon steel to soft bronze or even rubber. You need an abrasive that will cut through the materials you are working with. Here’s a quick list of some of the most common types.
Aluminum Oxide – Most Common
If you’re looking for an abrasive that most wheels are bonded with, you want aluminum oxide. It is used for everything from carbon to alloy steel, wrought iron, and bronze. This particular abrasive comes in a variety of styles that work with different materials. Be sure to look at the designation of the specific aluminum oxide abrasive and what it works best with.
Zirconia Alumina – Rough Grinding
When you want an abrasive for rough and tough cutting that lasts a long time, you need zirconia alumina. This abrasive uses a mix of aluminum oxide and zirconium oxide to create a durable surface that works great in cut-off applications for steel and steel alloys.
Silicon Carbide – Non-Ferrous Grinding
For a super sharp grinding surface, silicon carbide may be what you need. It works well on non-ferrous materials like rubber, stone, plastic, and glass, and also cuts through cast iron, soft bronze or aluminum. Expect to replace this abrasive more frequently than normal. It is very sharp, but can also be brittle, so it doesn’t last as long as an aluminum oxide surface.
Ceramic Aluminum Oxide – Top of the Line
One feature that makes a good abrasive is the consistent break down of the grains to form a sharp cutting surface. With ceramic aluminum oxide, that breakdown is taken to the next level with a fracture rate which is controlled down to the sub-micron level.
After a period of use, the grains break down yet your surface remains just as sharp. Breaking the grains provides brand new cutting points. This makes ceramic aluminum oxide the abrasive of choice when working with the hardest metals and precision grinding projects.
DXP is Your Trusted Metalworking Abrasives Supplier
The abrasives on your grinding wheel determine the tool’s best uses. You don’t want to use a stiff abrasive on a delicate project.
Before you start your next cutting project, reach out to our team for expert advice on the abrasive type you need. Every abrasive comes in a variety of grades, so you might want to explore your options with our MRO distributors before setting up your grinding wheel.
Whether you have questions about grinding wheel uses or need to know which tool is right for your project, our experts are here to help.
Contact DXP today to learn more!
Understanding Grinding Wheels
First in a series of articles written exclusively for White Cap customers, this article provides a basic understanding of grinding wheels, their construction, how to choose the best wheel, and how the right combination of an adhesive and abrasive can make or break a job.
To learn more about how to choose the right abrasive wheel for any job, maintenance tips, and safety best practices, check out Abrasive wheel Selection and Applications.
What Are Grinding Wheels?
An abrasive wheel creates a high-quality finish on surface materials, such as steel, glass, copper, stone, even concrete, with shape and dimension.
An Abrasive Wheel is a precision cutting tool with an abrasive surface coated with thousands of hard, sharp grains that cut, chip and grind away metal, steel, copper, cast iron, stainless steel, stone, concrete, and other tough materials. The sharp grains are bound with a special adhesive to a backing, usually in the shape of a wheel.
As the wheel rotates on a grinder, the wheel “grinds” the surface, causing the sharp grains of the wheel to break off, exposing new sharp edges. When the grains wear down, they fall off the bonded backing, exposing sharper new grains in their place. As the grains grind away, the surface material is removed in small chips or thin ribbons. The process continues until the desired surface finish or shape is achieved.
Available in a wide variety of types, shapes, patterns, sizes, and abrasives, there are several factors to consider when choosing an abrasive wheel.
Grinding Wheel Types
Abrasive wheels come in a variety of shapes and sizes. The most common and easily recognizable one is the straight abrasive wheel. The part of any abrasive wheel that does the actual grinding work is called the “grinding face.” The grinding face may be on the center of the wheel, recessed, only on the edges, or be broken into segments, designed to funnel lubricants, which keep equipment and materials cool. Here are the most common wheel types.
The Five Primary Types of Abrasive Grains
Let’s review the four main types of grains used on abrasive wheels. These can also be blended for specific applications and performance.
Aluminum oxide grains are tough and hard-wearing; however, after a sharp, fast initial cut, the grains dull and lack the cut-rate and life span of other grains. Good for grinding metals such as steel, iron, bronze alloys, stainless steel and other ferrous metals. Great value and cost effective with excellent quality and consistent performance.
Zirconia alumina grains provide fast cuts, are very heat resistant, self-sharpening, and deliver Rapid, consistent grinding on steel and stainless steel. They are also good for high-pressure machining and grinding because the pressure makes the grains break down quickly, exposing sharper edges. Zirconia alumna costs more than aluminum oxide, but it lasts longer.
Ceramic alumina is a newer abrasive type with a micro-grain structure that breaks down into smaller pieces, giving it the longest operating life in moderate to high pressure, generates less friction meaning it stays cooler in use, self-sharpening, fast cut rate, and minimizes heat discoloration on your workpiece. Ideal for hard-to-grind metals: armored steel, titanium, hard nickel alloys, tool steel, and stainless steel.
Silicon carbide grains are extremely hard, very sharp, fast cutting but break off easily under high pressure. Harder than aluminum oxide and versatile for grinding soft metals like aluminum, copper, or cast iron as well as hard materials such as cemented carbide, stone and concrete.
Silicon carbide/aluminum oxide blend creates a wheel ideal for grinding aluminum and other soft alloys. These grains offer extended life spans and fast, consistent cut rates.
Grit, or grain size, ranges from coarse to fine. and is indicated by a number shown on the abrasive wheel’s label The larger the grit number, the smaller the grain, and the finer the finish. Large/coarse grains grind larger chips resulting in a rougher finish.
The bond (sometimes called a matrix) is the “glue” that holds the key elements to a grinding wheel. the abrasive grains. Bonds help to determine the type, the characteristics, and the performance of a grinding wheel. The stronger the bond, the longer the grains adhere to the wheel. This means that sometimes a weaker bond is a better choice when cutting strong, tough metals that need razor-sharp abrasive grains.
Vitrified: (V) Made from clays and fusible materials. Not susceptible to water, oils, acids, or temperature variations. Ideal for high stock removal and precision grinding projects.
Grinding Wheel Safety. Best Practices
- Always wear protective safety glasses or face shield with impact-resistant lenses and side guards.