Stone abrasive tool characteristics and differences

Grinding is a method of cutting a workpiece on a grinding machine using a grinding wheel as a cutting tool. The features of this method are:
(1) Because the grinding wheel abrasive grain itself has high hardness and heat resistance, grinding can process materials with high hardness, such as hardened steel, cemented carbide, etc.
(2) The characteristics of the grinding wheel and grinding machine determine that the grinding process system can make uniform micro-cutting, generally ap=0.001~0.005mm, and the grinding speed is very high, generally up to v=30~50m/s; The rigidity of the grinding machine is good; Thanks to the hydraulic transmission, high machining accuracy (IT6~IT5) and small surface roughness (Ra=0.8~0.2μm) can be achieved economically for grinding. Grinding is one of the main methods of finishing parts.
(3) The temperature of the grinding zone is very high due to severe friction. This can cause stress and deformation of the workpiece, and even cause burns on the surface of the workpiece. Therefore, a large amount of coolant must be injected during grinding to reduce the grinding temperature. The coolant also acts as chip evacuation and lubrication.
(4) The radial force during grinding is very large. This results in an elastic setback of the machine-wheel-workpiece system, making the actual depth of cut smaller than the nominal depth of cut. Therefore, when the grinding is about to be completed, the grinding should be carried out without entering the tool to eliminate the error.
(5) After the abrasive grain is blunted, the grinding force also increases, causing the abrasive grain to break or fall off, and the sharp edge is re-exposed, which is called "self-sharpening". Self-sharpening enables grinding to be carried out normally within a certain period of time, but after a certain working time, manual dressing should be carried out to avoid vibration, noise and damage to the surface quality of the workpiece caused by the increasing grinding force.

Grinding Wheel
A grinding wheel is a grinding cutting tool, which is a porous object formed by many fine and hard abrasive particles and binders. Abrasive grains are directly responsible for the cutting work and must be sharp and have high hardness, heat resistance and a certain toughness. There are two commonly used abrasives: alumina (also known as corundum) and silicon carbide. Alumina abrasives have high hardness and good toughness, and are suitable for grinding steel. Silicon carbide abrasives are harder, sharper, and thermally conductive, but brittle, making them suitable for grinding cast iron and cemented carbide.
The grinding wheel of the same abrasive, due to its different thickness, the surface roughness and processing efficiency of the workpiece after processing are not the same, the coarse abrasive grain is used for coarse grinding, the fine abrasive grain is suitable for fine grinding, and the coarser the abrasive, the smaller the particle size.
The binder acts as a binder to the abrasive. Ceramic binders are commonly used, followed by resin binders. The selection of binders is different, which affects the corrosion resistance, strength, heat resistance and toughness of the grinding wheel.
The stronger the abrasive grain bonding, the less likely it is to fall off the grinding wheel, which is called the hardness of the grinding wheel, that is, the hardness of the grinding wheel refers to the difficulty of the abrasive particles on the surface of the grinding wheel falling off under the action of external force. Easy to fall off is called soft, and vice versa is called hard. The hardness of a grinding wheel and the hardness of an abrasive are two different concepts. The softer the surface of the workpiece to be ground is, the cutting edge (edges and corners) of the abrasive grain is less likely to wear, so that the abrasive grain can be used for a longer time, which means that a grinding wheel with a stronger bond (grinding wheel with higher hardness) can be selected. Conversely, grinding wheels with low hardness are suitable for grinding workpieces with high hardness.
The grinding wheel works under high-speed conditions, in order to ensure safety, it should be inspected before installation, and there should be no defects such as cracks; In order to make the grinding wheel work smoothly, a dynamic balance test should be carried out before use.
After a certain period of time, the surface voids of the grinding wheel will be blocked by abrasive chips, the sharp angles of the abrasive will be dulled, and the original geometry will be distorted. Therefore, trimming is necessary to restore cutting capacity and correct geometry. The grinding wheel needs to be trimmed with a diamond pen.