一级性色生活片毛片,黄片高清无码,一级特黄A毛片在线免费观看,欧美肥妇毛多水多bbxx,国产主播一区二区三区四区美女

It is generally believed that diamond wheel is not suitable for grinding gray cast iron due to the high chemical inertness between diamond and iron group elements. However, this only happens at high temperature. For example, when grinding with diamond grinding wheel, when the temperature reaches 650℃, diamond will oxidize in the air, while when it reaches 700℃~800℃, it will graphitize. At low temperatures these materials do not react with each other. Therefore, as long as the appropriate grinding speed and wet grinding method are adopted, and sufficient grinding fluid is supplied, the diamond wheel can grind the casting completely, which has been proved in the production practice. The grinding ratio (9600) of gray cast iron with a diamond wheel is much higher than (2700) of gray cast iron with a CBN wheel when wet grinding is used.

It is also generally believed that CBN grinding wheel is not suitable for grinding low carbon steel and other soft materials, because the grinding debris generated at this time will easily make the grinding wheel blocked. However, the current research suggests that the ceramic binder CBN grinding wheel can be used to improve the speed of the grinding wheel so as to form fine grinding chips, remove the grinding chips with high-pressure jet grinding fluid, and provide sufficient grinding fluid to prevent blockage of the grinding wheel. Therefore, CBN grinding wheel can grind low carbon steel (hardness greater than 30HRC) a class of soft materials. However, CBN grinding wheel is not effective for grinding any material. Usually it is not suitable for grinding hard alloy and the combination of hard alloy and steel. At this time, diamond grinding wheel has better effect.