Compare the bolts you have with the diagrams below, then refer to the appropriate chart to see the ideal tightening torque. Metric Bolt Torque Chart Refer to the charts below, which show the ideal tightening torque for each bolt grade for a variety of sizes. Identify the class by the embossed number on the head, then find the size of your bolt in the chart. The ideal tightening torque can be found listed in two columns to the right.

Metric Bolts - Tightening Torques - The Engineering ToolBox Metric Bolts - Tightening Torques - The Engineering ToolBox

Metric class 12.9 bolts are made from quenched and tempered alloy steel and see the most use in heavy-duty applications.Depending on size, they have a proof load of 580-600 MPa, minimum yield strength of 640-660 MPa, and a minimum tensile strength of 800-830 MPa. Class 8.8 bolts come in all sizes ranging up to 72 mm. They have a proof load of 970 MPa, minimum yield strength of 1100 MPa, and a minimum tensile strength of 1220 MPa. Class 12.9 bolts come in sizes ranging from 1.6 mm to 100 mm.

RS Eye bolt, metric fine thread - RUD RS Eye bolt, metric fine thread - RUD

They have a proof load of 830 MPa, minimum yield strength of 940 MPa, and a minimum tensile strength of 1040 MPa. Class 10.9 bolts come in sizes ranging from 5 mm to 100 mm. The “wet” column indicates lubricated bolts, whereas the “dry” column indicated unlubricated bolts. Metric Class 8.8 Bolt Torque ChartThey are made of quenched and tempered medium carbon steel and can be plated with a variety of materials, most commonly zinc. They are often used to secure engines and drives, alongside a host of other demanding applications. We hope these metric bolt torque charts have helped you discover the correct tightening torque for the bolts you use.