Choosing a Grinding Wheel

Grinding wheels are tools containing an abrasive-bonded surface which uses various materials to remove material from workpieces. Their type and severity dictate which abrasives, grit sizes and grades must be used depending on what kind of task needs completing.

Bonding of the abrasive grains together is of crucial importance, as it affects both speed and longevity of wheels. Different bonds feature various hardness levels and fracture toughness levels.

Abrasive Grit

When purchasing a grinding wheel, several characteristics should be taken into consideration. These include its abrasive grind, grit size and bond strength – its abrasive grind determines its ability to penetrate and remove material; soft materials like ductile metals have soft surfaces which create a tearing action when grinding that results in small chips of abrasive particles called “swarf,” while harder materials such as carbide and ceramic fracture easily while producing sharp chips which create sharpened chips known as swarf; when selecting your material type and grinding surface; these characteristics must also be taken into account before making your selection decision.

At present, four types of natural and manmade abrasives can be found both coated and bonded: emery, garnet, aluminum oxide and alumina-zirconia are popular choices that can be found both coated and bonded abrasives: emery, garnet, aluminum oxide and alumina-zirconia. Each offers different qualities like longevity, coarseness/aggressiveness and friability; these come in various grit sizes from disks to sheets – many can even be “stearated”, providing additional dry lubricant coating that improves performance further.

Silicon carbide, the most frequently used abrasive grain, possesses sharp and extremely hard grains with a Mohs hardness rating of 9. This material is widely used for nonferrous metals as well as harder materials like cemented carbide; fast cutting abrasives such as silicon carbide can even be utilized to grind very hard materials such as cemented carbide. A typical application for silicon carbide grinding wheels includes polishing rust off surfaces such as metal and glass surfaces or even refinishing wooden flooring surfaces.

Bond

Grinding wheel performance characteristics are determined by its abrasive grains, but also the bond holding them together. A wheel’s bond — made from substances such as vitrified, resinoid or organic resin — may either be hard or soft depending on its strength compared to external forces that try to pry loose the grains during grinding. Harder bonds provide greater resistance against these forces and keep more of its grains in place during use.

Ceramic alumina abrasive grains are an excellent choice for metalworking as they offer fast and smooth cuts while producing less friction than aluminum oxide abrasives, meaning less frequent wheel changes are necessary. Zirconia alumina is even tougher than standard aluminium oxide and self-sharpens while you grind; making it particularly suitable for hard-to-grind metals like armored steel, titanium, hard nickel alloys and Inconel(r). Zirconia also stands up well under heat pressures while maintaining its shape; making zirconia especially helpful in hard-to-grind metals such as armored steel, titanium hard nickel alloys and Inconel(r).

Resin-bonded abrasive wheels are excellent tools for smoothing warped pottery, removing glaze drips, and grinding off chips off finished pottery pieces. They also work great as rough sanders on materials with lower or medium tensile strengths such as alumina or silica; harder bond abrasives may be better suited for harder materials such as stainless steel or tool steels.

Grade

Selecting an ideal grinding wheel requires considering both the materials to be ground down, as well as size, shape, and surface finish requirements for the task at hand. In general, depending on what materials need grinding, materials will determine what kind of abrasive grains must be present within a wheel – aluminium oxide, zirconia alumina or silicon carbide being some popular choices.

Bond types that encase the abrasive grains also play a part in performance, with resininoid bonds, resinoid-rubber bonds and vitrified bonds among the most popular options. Resinoid-rubber bonds offer excellent rough grinding applications; quickly cutting through material while leaving behind a smooth finish.

Typically speaking, harder materials require coarser grains in their wheels, while softer materials benefit more from finer-gritted wheels. When working with hard and potentially brittle materials, finer abrasive grains help protect both wheel and workpiece or machine tool from accidental damage. As these finer grains grind through material they fracture it into small chips for removal from your workpiece or machine tool. As the abrasive grains wear through a workpiece, new particles become exposed. This process repeats until the wheel becomes too thin to be useful. Porous surfaces in an abrasive wheel allow air to escape during grinding processes, helping prevent heat build-up that could harm its grains.

Pores

Abrasive materials play an integral part of manufacturing, from smoothing welds on construction projects to cutting steel for automotive engines. The type of abrasive used in a grinding wheel determines both its speed and effectiveness; additionally, its smooth or rough finish depends on which grain size it employs; some materials require finer grit grinding while others call for coarser grains for proper penetration and removal of workpiece material.

A grinding wheel comprises of two components, an abrasive grain and bonding agent. These elements may include aluminum oxide, silicon carbide, zirconia ceramic alumina diamond or cubic boron nitride (CBN). As for its bonding agent it could either be vitrified glass-like material such as alumina; or it may consist of organic molecules like resin.

The present invention provides a grinding wheel containing low temperature vitrified bonds with reduced chemical reactivity towards silicon carbide grains, yet porous enough for debris clearance and coolant delivery during use. A new method for producing such wheels involves mixing green silicon carbide abrasive grains (60 grit) with conventional vitrified alumina-based bonds and hollow ceramic spheres in order to form it into wheels before subjecting it to high rate temperature cycling cycles, simulating an industrial manufacturing cycle.

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