How to work with the right grinding wheel

Good welding starts with good preparation, while good welding preparation starts with a clean cut. However, cutting is a technique that requires skill and knowledge, how to choose and utilize the best hand grinding wheel to do the job.

The type of grinding wheel used in a given application is highly dependent on the material to be cut. Ultimately, there are no alternatives to appropriate technologies to save costs and increase productivity.

Abrasive – sand

Grinding wheels and other bonded abrasives contain two important components: the actual cutting of the abrasive particles and the bonding agent that holds the particles together and supports the abrasive particles during cutting. The structure of the grinding wheel depends on the percentage of sand and bonding and its spacing in the metal grinding wheel.

The specific abrasive used in the 10 inch sanding disc is selected based on how the silicon carbide grinding wheel interacts with the working material. The ideal abrasive is the ability to maintain sharpness with minimal passivation. When the passivation begins, the abrasive breaks and a new cutting point is formed.

Each type of abrasive is unique and has different hardness, strength, fracture toughness and impact resistance.

The most commonly used abrasive in 10 inch sanding disc is alumina. Typically, it is selected for grinding carbon steel, alloy steel, high speed steel, annealed wrought iron, wrought iron, bronze and similar metal abrasives. There are many types of alumina abrasives, each of which is specifically designed and blended for a particular type of grinding operation. Each type of abrasive has its own name. It is usually a combination of letters and numbers. These names vary by manufacturer.

Another type of abrasive is zirconia alumina, each made up of a different percentage of alumina and zirconia. This combination produces a strong, durable abrasive that is suitable for use in a variety of steels and steel alloys in rough grinding applications, such as in a truncating operation. As with alumina, there are many different types of zirconia alumina to choose from.

In order to grind gray iron, cold iron, brass, soft bronze and aluminum as well as stone, rubber and other non-ferrous metals, silicon carbide is used as the abrasive.

The latest major development in abrasives is ceramic alumina, a high purity grain produced by a gel sintering process. The result is that the abrasive can break at sub-micron levels at a controlled rate, resulting in thousands of new cutting points. This abrasive is extremely hard. It is primarily used for precision grinding of the most demanding steels and alloys. Abrasives are typically mixed with other abrasives in various percentages to optimize their performance for different applications and materials.

Once the grain is known, the next question is related to particle size. All grinding wheel regulations contain a number indicating this characteristic. The grit size is the size of a single abrasive grain in the grinding wheel. This number corresponds to the number of openings per linear inch in the final screen size used to screen the grain. In short, a higher number indicates a smaller opening in the screen through which the grain passes, while a lower number (eg, 10, 16, or 24) indicates that the wheel is thicker. The coarser the grain, the larger the material size removed. The coarse grains are used for rapid removal of the blank, and finishing is not important. A large number (eg 70, 100 and 180) are fine grinding wheels that are suitable for providing fine surface treatments, small contact areas and for use with hard, brittle materials.

Buying bonds

To effectively cut the abrasive in the grinding wheel, the grinding wheel needs to have the proper adhesion. Bonding is the material that holds the abrasive particles together for effective cutting. As the abrasive particles wear and expel, they must also wear away to expose new sharp particles.

Conventional grinding wheels use three main types of bonding. Each can impart different properties to the grinding action on the grinding wheel. The type of bonding chosen depends on factors such as the working speed of the grinding wheel, the type of grinding operation, the required precision and the material to be ground.

Most grinding wheels are designed with a ceramic bond consisting of a carefully selected mixture of clays. At the high temperatures generated in the kiln where the grinding wheel regulations is made, the clay and abrasive particles melt into a molten glass state. The glass forms a span that attaches each grain to the adjacent grain and supports the grain as it is ground during the cooling process.

Grinding wheels made of ceramic bond are very strong, strong and porous. They remove stock materials at high rates and grind them to precise requirements. In addition, they are not affected by changes in water, acid, oil or temperature.

Ceramic binders are very hard and also brittle like glass. They are broken down by grinding pressure.

Some keys are designed with organic materials. They soften under the action of grinding heat. Resin bonds are the most common type of organic bond. It is made of synthetic resin. For applications that require rapid removal of blanks and applications that require higher finish, resin bonded hand grinding wheels are ideal. They are made to run at higher speeds and are often used in manufacturing workshops, foundries, wheels in billet shops, and sharpening and gluing of saws.

Rubber is another organic bond. Rubber bonding provides smooth grinding and is typically used in wheels that require high finish, such as ball bearings and roller bearing races. They are also often used in cutting wheels where burrs and burns must be minimized.

The bonding strength is specified in the grade of the grinding disc. If the span between each abrasive grain is very strong and can be split against the grinding force, the abrasive will remain well bonded. If only a small amount of force is required to release the grain, the wheel is considered to have a soft slope. The relative amount of bonding in the grinding wheel determines its grade or hardness.

Hard grade wheels are used for longer wheel life, for jobs on high power machines and for small or narrow contact areas. In contrast, soft wheels are used to quickly remove blanks, work with large contact areas, and hard materials such as tool steels and carbides.

Grinding Wheel shape

The 4 grinding wheel have a variety of shapes. Usually, the product that people think of when grinding a wheel is a straight wheel. The ground surface is the part of the grinding wheel that is used for machining. It is located on the periphery of the straight wheel. A common variation in straight wheel design is the concave wheel, which is so called because the center of the large grinding wheel is recessed and can therefore be mounted on the machine tool spindle flange assembly.

Some of the cutting faces of the 10 inch sanding discs are on the sides of the wheels. These wheels are usually named after their unique shape, such as cylindrical wheels, cup wheels and dish wheels. Various shapes of bonded abrasive portions are sometimes assembled to form a continuous or intermittent face of the grinding wheel. These products are called subdivisions. Grinding wheels with cutting faces on the sides are often used to grind cutting tools and other hard-to-reach surfaces.

The installed grinding wheel is a small grinding wheel with a special shape. These shapes include a cone or plug that is permanently mounted on the steel mandrel. Used in a variety of off-hand and precision internal grinding operations.

put it together

Many factors must be considered to select the wheel that best fits the job. The first thing to consider is the material to be ground, which determines the type of abrasive required in the grinding wheel. For example, alumina or zirconia alumina should be used to grind steel and steel alloys. For cast iron, non-ferrous and non-metallic materials, silicon carbide abrasives should be selected.

Hard, fragile materials usually require a fine grit and a soft grinding wheel. Hard materials resist the penetration of abrasive particles and cause them to become dull quickly. As a result, the combination of finer grit and softer grades causes the abrasive particles to become dull and break, exposing fresh, sharp cutting points. Conversely, for soft, ductile and easily permeable materials, coarse sand and hard grade grinding wheels should be chosen.

Another aspect to consider is the amount of inventory to be cleared. Coarse abrasive particles are able to remove blanks quickly because they have greater penetration and heavier cutting ability, but if the workpiece material is difficult to penetrate, the slightly thinner wheel will cut faster because there are more cutting points Cutting is possible.

4 Grinding wheels with ceramic bonding can be cut quickly. If the amount of stock to be removed is small, or if the requirements for the topcoat are high, a resin, rubber or shellac adhesive should be chosen.

The speed of the wheel in operation also affects the choice of wheel combination. Typically, vitrification wheels are used at speeds of less than 6,500 surface feet per minute. At higher speeds, the vitrified bond may break. Organic bonding wheels are typically selected between 6,500 and 9,500 surface feet per minute. Working at higher speeds often requires specially designed metal grinding wheel for high speed grinding.

In either case, do not exceed the safe operating speed displayed on the wheel or its blotter paper. Can be specified in rpm or sfm.

The next aspect to consider is the area of ​​grinding contact between the grinding wheel and the workplace. Thicker grinding wheels and softer grinding wheels are used in wider contact areas. This ensures a free, cool cutting action under the heavier load imposed by the surface size to be ground. For smaller grinding areas, larger grinding wheels and higher grades are required to withstand greater unit pressure.

Next, you should consider the severity of the grinding action. This is defined as the pressure at which the 10 inch sanding disc and workpiece are held together. Some abrasives can withstand harsh grinding conditions when grinding steel and alloy steel.

Finally, the power of the grinding machine must be considered. Generally, harder large grinding wheel should be used on machines with higher power. If the horsepower is less than the grinding wheel regulations diameter, use a softer wheel. If the horsepower is greater than the wheel diameter, choose a harder wheel.

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