Sj-42型縮徑機屬于無切削加工設備，具有生產效率高、工藝簡單、易于操作、節約原材料、質量穩定等優點。它是利用液壓技術將圓鋼、螺紋鋼等須縮徑部分送入專用磨具內經冷縮壓成型，壓縮部分鋼材密度可大大提高，從而提高材料的抗拉強度。而塑性、沖擊韌性不減，使絲扣部分和桿體部分強度一致，解決了因車床剝皮而減小抗拉力和沖擊韌性的弊端。

SJ-42 type shrinkage machine belongs to the non-cutting processing equipment, with high production efficiency, simple process, easy to operate, save raw materials, quality stability and so on. It is the use of hydraulic technology will be round steel, threaded steel and other shrinkage parts into the special abrasive through the cold shrinkage pressure molding, compressed part of the steel density can be greatly improved, thus improving the tensile strength of the material. The plasticity and impact toughness are not reduced, which makes the wire buckle part and the strength of the rod part consistent, and solves the drawbacks of reducing the tensile force and impact toughness due to the peeling of the lathe.