Grinding Wheel technology parameters
The grinding wheel consists of two components: abrasive grit and bonding material. The abrasive grit used in the grinding wheel takes the form of fine grains of silicon carbide, alumina, diamond, or CBN. The size selected is dependent upon the desired sharpness and the hardness of the material to be cut. The bonding material holds the abrasive grit together to form the grinding wheel. The selection of the bonding material is based upon several factors such as intensity of grinding action, heat resistance, accuracy of shape and size, versatility of use, and cost.
Abrasive Grain Sizes
The primary factor that determines the abrasive grain size is the grinding application. Abrasive grain size is measured in microns or a-scale numbers. The larger the micron size or a-scale number, the smaller the abrasive grain size. Smaller types with designations of a 120-grade will have a higher sharpness than a 60-grade with larger microns or a-scale numbers.
Bond Material Types
The type of bond material selected for the grinding wheel is dependent upon the material to be cut and the application. Bond materials range from soft organic materials used for grinding carbide and other hard material, to hard metal bonds for high speed steel and other tough materials. Bond types include metal, shellac, silicone carbide, rubber, and resin.
Grinding Wheel Diameters
Grinding wheels are available in a range of sizes, from as small as one-eighth of an inch, to as large as 24 inches. The hardness of the material being cut dictates the diameter of the grinding wheel to be used. Soft materials such as aluminum require a smaller diameter grinding wheel, while harder materials require a larger diameter grinding wheel.
Grinding Wheel Speeds
Grinding wheel speeds are measured in revolutions per minute (RPM). Generally, faster speeds are required for grinding harder materials while softer materials require slower speeds. Grinding wheel speed should never exceed the speed of the spindle at which it is used.
Grinding Wheel Feed Rates
The feed rate of the grinding wheel is determined by the rate at which the material is moved across the grinding wheel. Feed rates can be as small as 0.0001-inch per minute, to as high as 1000 inches per minute. Generally, the higher the feed rate, the faster the removal rate of the material being cut.
Coolants
Coolants are used when grinding materials in order to reduce friction and heat, as well as to flush away debris. Coolants are usually water-based and low-viscosity oils such as vegetable oil, mineral oil, or petroleum based oils. In some cases, special cutting fluids may be used.
Safety Guidelines
It is important to follow safety guidelines when operating grinding wheels. Always wear safety goggles to protect your eyes, and gloves to protect your hands. Always ensure that the grinding wheel is in good condition. Make sure that the grinding wheel is rotating at the correct speed, and that it is not overworking the material being cut. Be aware of the surroundings and ensure that the area is free of combustible materials.
