In recent years, with the rapid development of high-speed grinding and ultra-precision grinding technology, people have higher requirements about diamond grinding wheels. Grinding wheels with vitrified bond and resin bond can’t fully satisfy modern production requirements. The metal bond diamond grinding wheel has the characteristics of strong holding force, high bonding strength, good wear resistance, good forming performance, long service life, and can withstand large grinding pressure, etc., so the metal bond diamond grinding wheel is widely used in the grinding of difficult-to-machine materials, like engineering ceramic material, optical glass, hard alloy, etc.
Metal bond diamond grinding wheels could be classified into 3 categories, namely sintered metal bond grinding wheels, electroplated metal bond grinding wheels and single layer brazing metal bond grinding wheels.
The sintered metal bond grinding wheel is usually manufactured by high temperature sintering method with bronze or cast iron as bond. The advantages are high bonding strength, good forming performance, high temperature resistance, good thermal conductivity and wear resistance, long service life and high load resistance. However, due to the manufacturing process of the sintered diamond grinding wheel, the surface shape is randomly formed, and the geometry, distribution of the abrasive grains and the height of the cutting edge are inconsistent, and the abrasive grain distribution is not uniform. Therefore, only a few of the higher cutting edges of the abrasive particles can cut into the workpiece, limiting the improvement in grinding quality and grinding efficiency.
Electroplated metal bond grinding wheel is usually made of nickel or nickel alloy as plating metal. It has the advantages of simple electroplating process, low investment, convenient manufacture and use, high precision, high working speed and long service life. For grinding wheels with high precision requirements, electroplating is the only manufacturing method. With these advantages, electroplated metal bond grinding wheels occupy a dominant position in high-speed and ultra-high-speed grinding. However, the electroplated metal bond diamond grinding wheel also has many shortcomings in the use process. The abrasive material is actually only embedded in the plating metal, so the holding force is small. And the diamond particles are prone to fall off during the high-speed grinding process. This leads to the overall failure of the process. The solution is to increase the thickness of the coating if the holding force is to be increased, so as to increase the holding force, so that the thickness of the coating is increased. As a result, the abrasive height and the chip space are reduced, making the grinding wheel easy to be blocked. And the heat dissipation is poor so that the surface of the workpiece is prone to be burn. These defects of the electroplated diamond wheel greatly limit its application in efficient grinding.
The single-layer brazing metal bond grinding wheels realize the chemical metallurgical combination among the diamond, the bond and the metal matrix with the brazing method in the vacuum furnace of the active brazing filler metal and the nickel-based brazing filler. This could avoid the problems of poor strength of the electroplating metal bond grinding wheel combination. So the bonding strength of the grinding wheel is improved, the strength, and the performance and life of the diamond abrasive tool are also improved. But the production process is complex and cost is high. It is a new metal bond grinding wheel in research and development.