Mechanics and Types of Abrasion
– Abrasion occurs when a harder abrasive material rubs against a softer material, wearing it away.
– Examples of abrasion include shoe soles wearing down steps and glaciers abrading stone valleys.
– Abrasives can be hard minerals or synthetic stones.
– The Mohs scale of mineral hardness is used to compare the hardness of different materials.
– Calcium carbonate, a softer mineral, is also used as an abrasive.
– Abrasives can be classified as natural or synthetic.
– Advances in material technology have made synthetic abrasives comparable to natural ones.
– Natural and synthetic abrasives come in various shapes, such as blocks, belts, discs, and wheels.
– Aluminium oxide is the most common abrasive used.
– Other common abrasives include silicon carbide, tungsten carbide, and garnet.
– Bonded abrasives consist of an abrasive material held together by a binder.
– The binder can be clay, resin, glass, or rubber.
– Grinding wheels and cutting wheels are examples of bonded abrasives.
– Lubricants are used to prevent heat build-up during the grinding process.
– Bonded abrasives need to be trued and dressed after use to maintain their effectiveness.
– Coated abrasives are abrasive materials that are coated onto a backing material.
– Examples of coated abrasives include sandpaper and abrasive belts.
– The backing material provides support and flexibility to the abrasive.
– Coated abrasives are commonly used for sanding and finishing surfaces.
– Diamond files are a form of coated abrasive, with metal rods coated with diamond powder.
Applications of Abrasives
– Abrasives are widely used in industrial, domestic, and technological applications.
– Common uses for abrasives include grinding, polishing, buffing, honing, cutting, drilling, sharpening, lapping, and sanding.
– Abrasives can be used on various materials, including metals, ceramics, and plastics.
– Different grit sizes are available for different applications, ranging from large grains to microscopic grains.
– The shape and composition of abrasives can vary greatly depending on the application.
– Sand, glass beads, metal pellets, copper slag, and dry ice can be used for sandblasting.
– Cutting compounds are examples of abrasives suspended in liquid, paste, or wax, used for automotive paint, silverware polishing, and optical media.
– Very fine rouge powder is used for grinding glass and jewelry making.
– Cleaning products may contain abrasives for surfaces like linoleum, tile, metal, or stone.
– Abrasive cleaners, such as cream, paste, steel wool, and non-woven scouring pads, are used for scouring metal pots and stoves.
Factors in Choosing Abrasives
– The shape, size, and nature of the workpiece and desired finish influence the choice of abrasive.
– Different abrasives, such as bonded abrasives, natural sharpening stones, and coated abrasives, are used for specific sharpening tasks.
– Health hazards can arise from dust produced during abrasion, and lubricants are often used to mitigate these hazards.
– Using an abrasive that is too hard or too coarse can remove too much material or leave undesired scratch marks.
– Softer or finer abrasives tend to leave finer scratch marks and may not significantly abrade certain objects.
– Smooth surfaces hinder the adhesion of paint and adhesives, while irregular surfaces provide better adhesion.
– Inflatable tire repair kits require abrasives for strong adhesion of self-vulcanizing cement.
– Knives used on glass or metal cutting boards can abrade the blades.
– Wooden cutting boards are preferred to prevent knife blade abrasion.
Effects of Excessive Abrasion
– Excessive abrasion or presence of scratches can diminish or destroy the usefulness of objects like optical lenses and knives.
– Scratches can trap dirt, water, or other materials, increase surface area, erode coatings, and cause objects to wear away quickly.
– Increased friction can occur in jeweled bearings and pistons due to abrasion.
– Finer or softer abrasives leave finer scratch marks and may result in a grainless finish.
– Different chemical or structural modifications can be made to alter the cutting properties of abrasives.
Related Concepts and Additional Resources
– Abrasive blasting, erosion, steel abrasive, and tribology are related concepts to abrasion.
– PALANNA’s ‘ENGINEERING CHEMISTRY’ and the Abrasives engineering glossary are relevant references.
– ‘Grinding Stresses’ is a publication by the Grinding Wheel Institute.
– Care of laminate surface is important to prevent abrasion.
– Nutrimetics’ Honey and Almond Scrub is mentioned as an abrasive product.
– External resources include Wiktionary’s definition for ‘abrasive’ and Colliers New Encyclopedia from 1921. Source: https://en.wikipedia.org/wiki/Abrasive
An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away by friction. While finishing a material often means polishing it to gain a smooth, reflective surface, the process can also involve roughening as in satin, matte or beaded finishes. In short, the ceramics which are used to cut, grind and polish other softer materials are known as abrasives.
Abrasives are extremely commonplace and are used very extensively in a wide variety of industrial, domestic, and technological applications. This gives rise to a large variation in the physical and chemical composition of abrasives as well as the shape of the abrasive. Some common uses for abrasives include grinding, polishing, buffing, honing, cutting, drilling, sharpening, lapping, and sanding (see abrasive machining). (For simplicity, "mineral" in this article will be used loosely to refer to both minerals and mineral-like substances whether man-made or not.)
Files are not abrasives; they remove material not by scratching or rubbing, but by the cutting action of sharp teeth which have been cut into the surface of the file, very much like those of a saw. However, diamond files are a form of coated abrasive (as they are metal rods coated with diamond powder).
