通常使用和磨具同时制造的试样——“8字块”来比较评价磨具的强度,“8字块”的极限抗张强度σ。是用拉断力P与试样整体几何横截面积F(未扣除气孔截面)之比来算出的,即σ_p=P/F。但这个方法并不反映结合剂和磨粒材料的实际强度。所得到的与试样拉断相对应的拉伸应力是较低的。下表列出的砂轮在回转时所产生的最大切向应力(σ_T,牛顿/平方毫 Comparisons of the strength of the abrasives, the ultimate tensile strength σ of the “8-block”, are usually made using a specimen produced simultaneously with the abrasive - “8-character block”. Is calculated using the breaking force P and the overall geometry of the cross-sectional area F (without stomatal cross-section) to calculate the ratio, that is, σ_p = P / F. However, this method does not reflect the actual strength of the binder and abrasive material. The resulting tensile stress corresponding to pull-off of the specimen is lower. The following table lists the maximum tangential stress (σ_T, Newtons per square millimeter