Abrasives are the hard materials that are used for polishing, smoothening, and grinding of the metals and non-metals material surfaces. The main characteristics of a standard quality abrasive are its hardness and brittleness. Some abrasives are hard and cut any other hard metal for example diamond, which is the hardest material at present. It is a natural abrasive and because of its hardness, diamonds are useful to cut, grind, or drill other materials.
Abrasives Definition
An abrasive is either a natural mineral or a synthetic substance used for scraping and to give a specific form, finishing, and structure to a workpiece. In order to achieve a shiny, and smooth mirror finish surface, sometimes materials also require polishing.
Roughening can also be used in the process as satin, polished, or beaded finishes. According to an example, ceramic is an abrasive which we use to cut, grind and polish other softer materials.
Abrasive Materials: Their Composition And Properties
Abrasives are hard crystal materials that are either natural or synthetic. Aluminum oxide, silicon carbide, cubic boron nitride, and natural or industrial diamonds are the most common abrasive materials. Garnet, zirconium, glass, and walnut shells also prefer for some specific applications.
The abrasive materials are mainly classified in two forms, natural or synthetic abrasives.
Natural abrasives: Diamond, corundum, and emery are some natural abrasives. They originate from natural resources and can be extracted and processed with no modification for use.
Synthetic abrasives: On the other hand, synthetic abrasives are the output of substantial refining of raw materials or chemical byproducts. It includes silicon carbide, industrial diamonds, and alumina (a synthetic form of corundum).
Today, Many natural abrasives are being substituted by synthetic abrasives because all industrial uses need specific and consistent properties. Most of the natural abrasives (except natural diamonds) characteristics are too complex and variable.
Hardness is the most important advantage of abrasive material. They are hard to grind, clean, or extract than the material it is.
Types of Abrasive.
There are two types of abrasive.
- Natural.
- Artificial or Synthetic.
Natural abrasives are natural minerals or rocks found during mining in the crust of the earth. For example, Diamond, Garnet, Corundum, and Quartz.
While Synthetic abrasives are classified as a variety of materials with very higher strength and hardness. Carborundum, Aluminum Oxide, and Glass are some artificial abrasives.
The below table list shows natural and synthetic abrasive materials that are used in many industrial applications.
| Natural Abrasives | Synthetic Abrasives |
| Industrial Diamond | Synthetic Diamond |
| Corundum | Silicon Carbide |
| Emery | Aluminum Oxide |
| Garnet | Boron Carbide |
| Quartz | Zirconia Alumina |
| Flint | Glass |
Forms of Abrasives
Abrasives are generally used in two main forms blocks and powder form.
- Block form abrasive: It is created by the cutting of the abrasives material into small pieces in specific shapes. They are used as grindstones, whetstones, millstones, and cutting edges.
- Powder abrasive: It is crushed abrasive materials. Natural or synthetic abrasives are crushed and form in different grades and sizes. The abrasive powder form can be used as such form and also for bonding it on cloth or paper (coated & bonded abrasive).
Applications & Uses of Abrasives
Abrasives are very essential for grinding wheels, sandpapers, sharpening stone blocks, polishing, cut-off wheels, and other industrial applications. These include the automobile industry, aircraft and space vehicles, mechanical and electrical equipment, and machine tools.
The major abrasives applications include polishing, grinding, and surface finishing of metals, non-metals, leather, wood, stones, and other materials.
Some abrasives (diamond and carborundum) are specific for cutting, boring, and drilling tools.
Applications of Abrasives
Some common applications of abrasives include grinding, buffing, honing, cutting, drilling, sharpening, lapping, and sanding.
In general, abrasives are used for the following applications:
- Surface cleaning, finishing, and removal of excess material from the metal surface.
- Grinding and sharpening and polishing of industrial tools and equipment.
- Smoothening of the material.
- Cutting applications of wood, plastic, aluminum, ferrous and non-ferrous metals.
- Abrasive discs such as buffing wheels carry a polishing compound that is used to smooth and polish metal jewelry.
Silicon carbide and aluminum oxide are very hard abrasive. They are sharp edge and brittle in nature. These sharp edges help to pass the abrasive into the working material and reduce the amount of heat produced during the abrasion.
Uses of Abrasives
Industrial uses & applications of abrasives are applicable in three main forms bonded, coated & loose.
- Bonded abrasives to shape solid tools like grinding wheels, cylinders, plates, cups, tool parts.
- Coated abrasives are backing cloth, paper sheets with abrasive material (sandpaper), strips, or belts.
- Loose abrasives use for polishing or tumbling in a liquid or solid carrier, (sandblasting for buildings).
What Are The Classification Of Abrasives?
It is essential to identify the material used to produce abrasives as either natural or synthetic. Diamond, corundum, and emery contain natural abrasives. They originate from natural resources and can be mined and processed with no further changes or modifications.Â
Emery, corundum, and diamonds are special types of abrasive uses for grinding wheels and sharpening tools.
Synthetic abrasives are more popular in industrial applications than natural abrasives. For that reason, synthetic abrasives are superior & more successful. Aluminum oxide, silicon carbide, boron carbide, and titanium carbide are synthetic materials. Mainly used for grinding ferrous metals and non-ferrous metals.Â
Aluminum oxide is usually more common among other synthetic abrasives. Around 40 percent is abrasive in a grinding wheel.
Synthetic Abrasives can either be bonded or coated.
- Bonded abrasive– Contains an abrasive material embedded inside a matrix, (consist of very fine abrasive of aluminum oxide). This matrix is referred to as a binder and is often composed of clay, resin, glass, or rubber.
- Coated abrasive– It is made by binding abrasive grains to a flexible sheet using adhesives. In coated abrasive products abrasive grains are bonded to paper or cloth. They are crated in various forms, such as a disc, endless belt, and sheet.
Ending Note
Abrasives are important since they are necessary for all industries. Without their use, fine polishing, sharpening, and shaping of the various tool are not possible.