The triangle is one of the core parts of the circular knitting machine. Its main function is to control the movement and the movement of the knitting needles and the sinkers. It can be roughly divided into the full needle (circle) and the triangle (half the needle). Triangle, plain (float) triangle and sinker triangle. The overall quality of the triangle, will have a great impact on the circular knitting machine and fabric, so pay special attention to the following points in the purchase of the triangle: First of all, we must choose the corresponding triangular curve for different fabric and fabric requirements. As the designer pursues different fabric styles and focuses differently, the triangle face curve will be different. Secondly, because the knitting needle (or sinker) and the trigonometric sliding friction at high speeds for a long time, individual process points also have to withstand high-frequency impact, so the raw materials and heat treatment process used in the triangle are very important. Therefore, the triangular raw materials are generally selected national standard Cr12MoV (Taiwan standard / Japanese standard SKD11), the material hardenability, quenching deformation is small, quenched after the hardness, strength, toughness are more suitable for the requirements of the triangle. The quenching hardness of the triangle is generally HRC 63.5±1. Excessively high or low hardness of the triangle can have adverse effects.