A grinding wheel is a wheel used for grinding. Grinding wheels are composed of abrasive compounds and are used for various grinding (abrasive cutting) and abrasive machining operations. Such wheels are used in grinding machines. The wheels are generally made with composite material . This consists of coarse-particle aggregate pressed and bonded together by a cementing matrix (called the bond in grinding wheel terminology) to form a solid, circular shape. Various profiles and cross sections are available depending on the intended usage for the wheel. They may also be made from a solid steel or aluminium disc with particles bonded to the surface. Today most grinding wheels are artificial composites made with artificial aggregates, but the history of grinding wheels began with natural composite stones, such as those used for millstones. The manufacture of these wheels is a precise and tightly controlled process, due not only to the inherent safety risks of a spinning disc, but also the composition and uniformity required to prevent that disc from exploding due to the high stresses produced on rotation. Grinding wheels are consumables, although the life span can vary widely depending on the use case, from less than a day to many years. As the wheel cuts, it periodically releases individual grains of abrasive, typically because they grow dull and the increased drag pulls them out of the bond. Fresh grains are exposed in this wear process, which begin the next cycle. The rate of wear in this process is usually very predictable for a given application, and is necessary for good performance.
Drills are cutting tools used to remove material to create holes, almost always of circular cross-section. Drills come in many sizes and shapes and can create different kinds of holes in many different materials. In order to create holes drill bits are usually attached to a drill, which powers them to cut through the workpiece, typically by rotation. The drill will grasp the upper end of a bit called the shank in the chuck. Drills come in standardized drill bit sizes. A comprehensive drill bit and tap size chart lists metric and imperial sized drills alongside the required screw tap sizes. There are also certain specialized drill bits that can create holes with a non-circular cross-section. Most drill bits for consumer use have straight shanks. For heavy duty drilling in industry, bits with tapered shanks are sometimes used. Other types of shank used include hex-shaped, and various proprietary quick release systems. The diameter-to-length ratio of the drill bit is usually between 1:1 and 1:10. Much higher ratios are possible (e.g., "aircraft-length" twist bits, pressured-oil gun drill bits, etc.), but the higher the ratio, the greater the technical challenge of producing good work. The best geometry to use depends upon the properties of the material being drilled.
Grinding is a mechanical method of removing material, refers to the processing method of removing excess material on the workpiece with abrasives and abrasive tools. Grinding is one of the most widely used material removal methods. Grinding processing belongs to finishing processing in mechanical processing (machining is divided into roughing, finishing, heat treatment and other processing methods), with less processing volume and high precision. It is widely used in the machinery manufacturing industry. Carbon tool steel and carburizing and quenching steel parts that have been heat treated and quenched often have a large number of regularly arranged cracks on the surface that is basically perpendicular to the grinding direction during grinding-grinding cracks , it not only affects the appearance of the part, but also directly affects the quality of the part.