Forney's Knowledge Center: Abrasives

Posted by Rachel Bigum on Sep 23, 2019 9:19:00 AM

In Forney Industries, Abrasives, curved edge flap discs, DIY, "cutting wheels

Micro-Abrasive Grinding

Although Forney Industries is widely known for their machines and welding products, they have a extremely impressive line of abrasive products. Check out the information below to help you decide which abrasive products to buy, and how to use them correctly.

Steel Cutting and Grinding

Steel cutting and grinding products are perfect for welding and metalworking support. Ideal for every-day DIYers, and folks in the farm & ranch, automotive and industrial industries. This category also includes sanding discs, and mounted flap wheels.

Masonry Cutting and Diamond Blades

Diamond blades are perfect for cutting granite and tile. There are many different grades of diamond blades on the market today, from inexpensive one-day use, to more expensive blades used by contractors that can make thousands of cuts on a variety of materials.

Grinding and Shaping

Micro Abrasives can replace many of the small cutting and grinding as well as polishing items offered by several other companies, mainly Dremel®. There are several other maintenance and repair items offered, such as Carbide Burrs, Rotary Rasps and Files, Buffing Compounds and Polishing Wheels, just to name a few. These products sell most frequently in the Hardware, Farm & Ranch and Automotive markets.

How To Read a Wheel

Most abrasive manufacturers use standard codes to identify wheel properties. The wheel’s specification number offers information about grain type, grain size, hardness of bond, type of bond and the reinforcing material.

Grain Type A = Aluminum Oxide

Grain Type ZA = Zirconia Alumina

Grain Type C = Silicon Carbide

The number that follows the grain type is the grain size, or grit; the smaller the number, the larger the grit. A letter grade indicates the hardness of the bond, with A being the softest, and Z the hardest. Wheels usually fall between M and V.

The last two letters, if used, indicate the type of resin used for bonding, and the reinforcing material used in the wheel. B indicates a Diamond Bladephenolic resin, and the F indicates fiberglass reinforcement. As an example, a wheel designated A24-R is Aluminum Oxide, 24-grit, toward the harder side of the scale. Many types of wheels have a phenolic resin bond and fiberglass reinforcement as standard, so a BF designation may not appear on the wheel itself.  

Like all tools, an abrasive wheel must be matched to the application if it is to perform as designed. If you have any doubt about proper wheel selection for your grinder or application, always contact either the tool or abrasives manufacturer for assistance. It is the user’s responsibility to refer to and comply with ANSI B7.1 safety requirements.

How to Select Abrasive Wheels

Cutting or grinding with an abrasive wheel is just as much a metal cutting process as milling, turning, filing or sawing. The only difference is the abrasive wheel has thousands of tiny cutting edges instead of the few large ones the other processes encompass. When cutting or grinding with an abrasive wheel, thousands of new cutting edges are exposed as the wheel wears down.

The simple technical description of an abrasive wheel is “a cutting tool consisting of abrasive grains held together by organic or inorganic bonds.” Abrasive grains are extremely hard substances such as aluminum oxide, zirconia alumina and silicon carbide that are embedded in a matrix called the bond. The bond not only holds the abrasive grains together, but also allows the mixture to be shaped to the desired wheel form and, after suitable treatment, to take on the necessary mechanical strength for its intended work.

Inorganic bonds include clay, glass, porcelain, sodium, silicate, magnesium oxychloride and metal. Organic bonds include shellac, rubber, synthetic resin, or resinoid. Resinoid bonds are commonly used to make wheels for metalworking applications.

The degree of hardness possessed by the bond is call its grade. Grade also indicates the ability of the bond to hold the abrasive grains in place. A soft bond permits the grains to break away more readily than a hard one and should be used where the abrasive becomes rapidly dulled or blunt (when grinding hard materials). A hard bond retains the abrasive grains longer and should be used when grinding soft materials. A simple reuse to follow is to use a hard wheel for soft materials and a soft wheel for hard materials. Remember that the “hardness” or “grade” of a wheel bears no relation to the abrasive material used in its construction. Therefore, a soft grade wheel can be made of the hardest abrasives, and a hard grade wheel can be made of the softest abrasives.

Resin-Bonded Grinding Wheels

The following are things to consider when selecting resin-bonded grinding wheels for your application.

Type of abrasive

Aluminum oxide is made of clay-like material called bauxite and is reddish brown in color. It is a good choice for use on ferrous metals and alloys with high tensile strength because it offers greater toughness for coping with the greater grinding resistance of these materials.

Zirconia alumina is also suitable for ferrous metals and high-tensile-strength alloys, but is usually used for higher horsepower or Grinding Wheelsintense applications. Zirconium offers a very sharp, long-lasting grain that results in faster grinding and cutting. While the initial cost is higher than other wheels, it can be a more economical choice in the long run for high-volume users as it offers better performance and a longer life cycle.

Silicon carbide is used on nonferrous metals, such as copper, aluminum, and bronze. It can also be used on low-tensile-strength metals, such as cast iron and ductile iron. It is also the only resin-bonded abrasive used effectively on asphalt, concrete, stone and marble. Silicon carbide fractures easily, so it provides new cutting edges with minimum wheel wear when grinding these low-resistance materials.

Abrasive Grain Size

Use a larger grain for softer materials such as mild steel or green concrete. Use a smaller grain size for harder steels or cured concretes.

Hardness or Grade

As previously mentioned, hard materials like stainless steel or high-carbon steel work best with a softer grade. This allows the dull grains to release more readily so new sharp grains are constantly exposed.

Softer materials won’t dull the grains as readily, so a harder grade wheel that holds the grains in the wheel for a longer period can be used.

Grinding Machine Power

High horsepower machines typically need a harder grade and smaller grain size. Low horsepower machines typically use a softer grade, and larger grain size.


Double Cut- DC:
With their precision cutting action, Double Cut produces small chips instead of long slivers. This eliminates clogging. Ideal on steel/stainless steel alloys and exotic metals. 

  Single Cut- AL:
The mill style flute allows for fast chip flow and fast stock removal. Ideal for aluminum and non-ferrous meals.

Cylindrical burr with plain end

Cylindrical burr with end cut
Cylindrical burr with radius end
Ball-shaped burr
   Oval-shaped Burr 

Tree-shaped burr with radius end
Tree-shaped burr with pointed end

Taper burr with radius end
*It is the user’s responsibility to refer to, and comply with, ANSI B7.1 safety requirements.

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