Hexagon socket head screws are also called hexagon socket bolts for short. Similar to countersunk screws, the head of the screw is embedded in the machine parts, and the connection strength is relatively large, but the corresponding specifications of the hexagon wrench must be used to install and remove the screws. Generally used on various machine tools and their accessories. Hexagon socket bolts are divided into ordinary and high-strength according to the grade strength. Ordinary hexagon socket bolts refer to grade 4.8, and high-strength hexagon socket bolts refer to grade 8.8 or above, including grade 10.9 and grade 12.9. Grade 12.9 hexagon socket bolts generally refer to black hexagon socket head screws with knurling, natural color and oil.
