2015-12-28
Abrasives are commonly used in a wide variety of industrial processes including the shaping and finishing of components made from various materials such as wood, glass, concrete, plastic, stone, iron, steel, super-alloys and non- ferrous metals, and more exotic products such as jewels, optical and electronic components.
Historically, abrasive materials were primarily derived from natural minerals such as emery, quartz sand and diamond. Today, however, the abrasives industry is almost entirely dependent upon synthetic materials, which are far more consistent in composition and cost-effective than their natural predecessors. Synthetic materials are generally more cost-effective as they tend to be by-products or waste streams of the processes that produce them such as power generation and metal smelting. While natural minerals are still prevalent, they tend to be used for highly specialized applications such as polishing and fine finishing due to their higher cost.
The three primary types of production abrasives are coated, bonded and loose abrasives. Coated abrasives have a paper, cloth or other similar backing. Bonded abrasives include grinding wheels and sticks. Loose abrasives are used for blasting and tumble for, among other things, the removal of paint and rust and the preparation of new surfaces. Each type of abrasive product caters to different requirements in terms of the surface finish specifications, the shape and size of the component, its physical properties (such as hardness, strength and temperature limits) and the detailed requirements of the specific grinding or finishing process. The characteristics of the abrasive material (for example, size, shape, strength, density and hardness) are critical to its specific use, as are the properties of the matrix material (for example, resin, vitreous or metal) and degree of porosity.
Applications for loose abrasives range from surface cleaning and peening, to the restoration and surface preparation of materials for protective coatings. A second major market for loose abrasives is the blast cleaning and repainting of bridges and overpasses. In addition to these two markets, there are hundreds of industrial applications where loose abrasives are used for surface preparation, surface cleaning and as a component of other finished products.
Abrasive blast cleaning encompasses a variety of methods that include the use of several types of media propelled by water or air. The abrasives media vary widely, from rice hulls and walnut shells to various slags, garnet and steel shot. Typical blast cleaning minerals include staurolite, olivine, specular hematite and garnet. Man-made media used for blast cleaning include plastic, coated minerals, recycled glass, steel shot, coal slag, copper slag and nickel slag.
For over 50 years, silica had been the most commonly used abrasive for abrasive blast cleaning, thus the coining of the term sandblasting, as it is economical and easy to use.
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Post time: Dec-28-2015