The choice of binder and abrasive is closely related. For example, the use of CBN generally requires the grinding wheel to keep its shape unchanged during use and not be removed from the machine tool until it is consumed completely. As the thermal conductivity of CBN is very good, it is more advantageous to use metal bond. The combination of the two provides the conditions for cold cutting. Because the cutting heat is transmitted through the abrasive and grinding wheel, and then carried away with the coolant, it is much faster than entering the workpiece.
There are two forms of metal bond: electroplating and sintering. Electroplated grinding wheels are not trimmed, they are made into the correct shape at the beginning and used until they are exhausted. Sintered metal grinding wheels are usually trimmed by electric spark, and then installed on machine tools like electroplated grinding wheels. The radial runout of sintered and electroplated grinding wheels installed on the spindle shall be less than 0.0125mm. For metal bonded grinding wheels, it is very important to reduce spindle runout.
Because the distance that the abrasive grains protrude from the bond is very small, if the runout reaches 0.025mm, one end of the grinding wheel will be overloaded, causing excessive wear, and the other end will be lightly loaded and still sharp. Some electroplated grinding wheels can produce very small contour arc radius (about 0.125mm). However, the arc radius of most electroplated grinding wheels is greater than 0.5mm. Generally, electroplated grinding wheels are used for high-speed grinding, while metal sintered grinding wheels are suitable for grinding ceramic materials.
Monolithic metal bonded grinding wheel has a small range of adaptability to vibration, runout, coolant flow and other working conditions. If the rigidity of the grinder, workpiece and fixture is poor, or the bearing of the old machine tool is not in good condition, and there is no balancing device on the machine tool, the use of electroplated grinding wheel under this condition will lead to problems in the service life of the grinding wheel, workpiece finish and surface texture. According to the vibration and stability of the machine tool and other specific conditions, it is sometimes better to use resin bonded grinding wheels.
Resin bond has strong damping capacity to vibration. Of course, the equipment and time involved in the correction and dressing of resin bonded grinding wheels will increase the cost. Ceramic bond is most commonly used. Because the bonded grinding wheel has holes, the cutting fluid can effectively enter the grinding arc, and there are large holes to hold the wear debris. At the same time, the ceramic bonded grinding wheel can be easily trimmed to the correct shape and sharpened by using diamond tools.
Post time: Jan-16-2023