Abrasives scientific knowledge: the type and characteristics of introduction

Abrasives are used for grinding, lapping and polishing tools. Most artificial abrasive grinding with abrasive plus binders made from natural mineral rock is also useful for direct processing into natural abrasive. Abrasives except in machinery manufacturing and other metal processing industries are widely used, but also for the processing of food processing, paper industry and ceramic, glass, stone, plastic, rubber, wood portable belt  and other non-metallic materials. Abrasive during use, when the blunt abrasive, the abrasive agent itself or in conjunction with portions broken broken abrasive grains from the partial or complete loss of the working surface of the abrasive article and the emergence of new cutting edge, sharp or continuously exposing new abrasive grains within a certain time so that the abrasive cutting performance can be maintained. This self-sharpening abrasive, is abrasive tool compared with the general prominent feature. As early as the Neolithic Age, humans had already started to use natural millstone processing knives, stone axes, bone, horn, and tools such as a tooth; 1872, appeared in the United States with a combination of natural abrasive clay firing Ceramic wheel; 1900, the advent of artificial abrasives, using artificial abrasives manufacturing have produced a variety of abrasives, grinding and create the conditions for the rapid development of grinding machine. Thereafter, the abrasive nature of the decreased proportion of abrasive. Abrasives their source of raw materials, natural and artificial abrasive abrasive categories. Commonly used in machinery industry is only natural abrasive whetstone. Artificial abrasive at the basic shape and structure of distinction, there are wheel, grinding, stone, sand tile (collectively, abrasive) and coated abrasives five. In addition, the habits of the abrasive slurry as a class. Abrasive used by the abrasive can be divided into ordinary abrasive abrasive and superabrasive abrasive. The former corundum and silicon carbide abrasive general, the latter made of diamond and cubic boron nitride and other superhard abrasive. In addition, there are some  abrasive sanding belt special varieties, such as sintered corundum abrasives etc.. Ordinary abrasive abrasive is bonded abrasive solid ordinary form a certain shape and a certain intensity of abrasive. Generally abrasive, binder and pore structure, which is often called the abrasive three parts of the three elements. In abrasive abrasive cutting action from the. Binding agent is a solid form of the abrasive loose abrasive materials, inorganic and organic types. Ceramic inorganic binders, such as magnesite and sodium silicate; organic resin, rubber and shellac. The most commonly used is a ceramic, resin and rubber binders. Holes in the ground of debris from the chip and chip effect, and can accommodate coolant helps grinding heat dissipation. In order to meet some special processing requirements, the pores can also dipped some fillers, such as sulfur and paraffin, etc., to improve the performance of the abrasive. This filler is also called the fourth abrasive elements. Said ordinary abrasive abrasive characteristics of the project are: the shape, size abrasive, grain size, hardness, organization and binding agents. Grit abrasive hardness refers to the external force, from the degree of difficulty shedding the abrasive surface, which reflects the bond abrasive grip strength. Abrasive hardness depends mainly on how much amount of binder added density and abrasive grit off easily expressed low abrasive hardness; vice versa, which means that high hardness. Hardness level is generally divided into super-soft, soft, soft, medium, medium hard, hard and superhard grade seven, from these levels can be subdivided in a number of small magnitude. Abrasive hardness measurement method, more commonly used hand cone, mechanical cone method, Rockwell hardness measurement method and blast assay.
Hardness and its dynamic modulus of elasticity abrasive has a corresponding relationship, which is conducive to the use of audio measurement abrasive method to represent the dynamic elastic modulus abrasive hardness. In grinding, the high if they are grinding the workpiece material hardness, generally used in low hardness abrasive; contrary, the use of high hardness abrasive. Coarse abrasive organization into tight, medium and loose categories. And number of each class can be further subdivided, with the organization number to distinguish. Abrasives organization number the greater the share of abrasive in the abrasive volume fraction is smaller, wider gap between the abrasive, the more loose tissue. Conversely, the smaller the organization, said more tightly No. organization. Loose abrasive organization is not easy when you use passive, less heat during the grinding process, the workpiece can reduce heat deformation and burns. Tight organization of abrasive grains not falling, help keep grinding geometry. Abrasives be organized only in the manufacture of abrasive formula by control, generally do not make the determination. Superabrasive abrasive primarily by diamond, cubic boron nitride and binding agent to form a solid abrasive. Because of diamond, cubic boron nitride high price, with good abrasion resistance, they are made with ordinary abrasive abrasive abrasive different, except for super abrasive layer, as well as the transition layer and the substrate. Superabrasive layer is a part of the cutting action, the super abrasive grains and a binder composition. Base support care role is played in the grinding of metal, bakelite or ceramic materials. For connecting the substrate and the buffer layer superhard abrasive layer comprising a binder  abrasive wheel and, sometimes, may be omitted. The binding agents are used resin, metal, plated metal, and ceramics. Bonded Abrasives manufacturing process are: distribution of material, mixing, forming, heat treatment, machining and inspection. With different binding agents, manufacturing processes are not the same. Vitrified abrasives used mainly-pressure method, the abrasive and binder weight ratio formula weighing, mixing evenly placed within the mixer, put in a metal mold in the press molding of abrasive rough. Blank firing kiln dried and then into the firing temperature is generally about 1300 ℃. When using a welded low-melting binder, the firing temperature is lower than 1000 ℃. Then the provisions of the exact size and shape processing, final inspection products. Resin bonded abrasives are generally molded in the press at room temperature, there is also pressurized with heating in a hot-pressing process under heating conditions. After forming in the hardening furnace hardening. The phenolic resin as binder, the curing temperature is 180 ~ 200 ℃. Rubber bonded abrasives used mainly for mixing roll machine and rolled into thin slices, then use a die cutter punching molding; also some with loose material, into the inner metal mold press forming. After vulcanization molding vulcanization tank, a temperature of 165 ~ 180 ℃. Metal bonded abrasives manufacturing process, there are two powder metallurgy and plating method, mainly for superabrasive abrasive. Bronze powder metallurgy as the binding agent, or after mixing by hot press molding at room temperature, and then sintering processing. Plating with nickel or nickel-cobalt alloy as the metal plating, according to the abrasive bonded to a plating process on a substrate made of abrasive. Special varieties of sintered corundum abrasives and grinding with abrasive fibers and so on. Sintered corundum abrasive is alumina powder and the amount of chromium oxide mixing, forming, sintering at about 1800 ℃. This abrasive compact structure, high strength, mainly used for processing watches, instruments and other parts. Abrasive fibers are adhered or containing abrasive filaments (eg nylon) as the raw materials made of, its flexibility, materials and products used in metal polishing.