硬度
Hardness

• 磨具硬度是指在磨削加工时，磨粒从磨具表面脱落的难易程度。
• 1.  在一般情况下，硬度较软的砂轮用于磨削较硬的工件，硬度较硬的砂轮用来磨削较软的工件。
• 2.  磨削时，工件与磨具的接触面大或进给量大时，应把磨具硬度选软些。成型磨削时，为保证工件几何形状的精度，可适当提高磨具的硬度。
• 3.  磨削导热性能差的工件和刃磨刀具时，为避免烧伤、退火，磨具硬度应选软些的。
• 4.  高速磨削时，磨具硬度应软些；干磨比湿磨用的磨具硬度也应软一些。

• The hardness of abrasive tools indicates the difficulty of abrasive grains falling off the surface of the abrasive tools in cutting .
• 1.  Generally, the grinding wheels in soft hardness are used for cutting harder workpieces, whereas the wheels in a bit higher hardness are used for cutting soft workpieces.
• 2.  In the process of cutting , if the workpieces is touched greatly or the feeding is large, it is available to select soft hardness . For forming-grinding , it is better to select the wheels in higher hardness to precision of the workpieces.
• 3.  When grinding the workpieces with weak capability of heat-transmission and cutting tools , it is better to select softer hardness to avoid burning and annealing.
• 4.  When grinding at high speed, it is better to select softer hardness. The hardness in dry grinding should be softer than that in wet grinding.