BS ISO 2540:2016规定了带保护倒角的B型中心孔的中心钻尺寸。它仅包括公制尺寸，被视为该类型钻头未来唯一的推荐尺寸。凹槽可以是直的或螺旋的，由制造商选择。除非另有说明，这些钻头都是右手切削。附录A给出了B型中心孔的建议尺寸，可通过合理使用本国际标准中列出的中心钻获得。交叉引用: ISO 866ISO 2541ISO 13399购买本文件时提供的所有当前修订版均包含在购买本文件中。

BS ISO 2540:2016 specifies the dimensions of centre drills for centre holes with protecting chamfer - Type B.It covers only metric dimensions, regarded as the only recommended dimensions in the future for this type of drills.The flutes can be straight or spiral at the option of manufacturer.Unless otherwise stated, these drills are right-hand cutting.Annex A gives the recommended dimensions for the centre holes, Type B, which can be obtained by a rational use of the centre drills listed in this International Standard.Cross References:ISO 866ISO 2541ISO 13399All current amendments available at time of purchase are included with the purchase of this document.