精密丝咀如附图所示(d=0.1～0.5毫米),用钨18铬4钒高速钢制造,要求淬火度硬R_C 58～62。采用盐浴炉加热,虽然能够防止氧化,保证尺寸, 但小孔被熔盐堵塞,清理困难;在箱式电炉里加热产生氧化,放了0.02～0.03毫米的研磨量,仍然不能保证成品尺寸。经过多次试验,我们找到了 Precision Tsui Tsui shown in the drawings (d = 0.1 ~ 0.5 mm), made of tungsten 18 chromium 4 vanadium high-speed steel, hardened hardness required R_C 58 ~ 62. The use of salt bath furnace heating, although able to prevent oxidation, to ensure size, but the hole is clogged with molten salt, cleaning difficulties; heating in a box-type furnace oxidation, put 0.02 ~ 0.03 millimeters of grinding, still can not guarantee the finished size. After many trials, we found it