"SHERWOOD"全磨制麻花钻头，主要钻削对象:铸钢、铸铁、可锻铸铁、铜、镍、铝合金和石墨等。

With precision-ground flutes and black finish (W-finish), this is the most common surface finish and is the result of a steam tempering operation in which steam is passed over the product during a controlled tempering cycle, producing a black oxide layer.

精密的全磨制表面（w-finish）光洁度是通过产品在回火周期控制的结果，表面有个黑色氧化层。

Black tools are generally recommended for ferrous applications where the oxide layer aids chip flow, helps to dissipate heat by retaining some coolant on the tool surface and also helps to prevent the tool from staining.

这种亚铁氧化层，有助于保持在工具表面的冷却液，也有助于防止工具在加工过程中有散热作用。

Supplied in indexing metal cases. Point angle: 118, helix angle: normal, web thickness: standard, relief angle: 10-20, tolerance of diameter: h8, tolerance of shank: f11. Manufactured to BS328/DIN338RN.

切削角度：118°，螺旋角：顺溜，腹板厚度：标准，后角：10-20°，直径公差：H8，柄部：F11。制造标准:BS328 / DIN338N。