Strap clamps ensure stability and accuracy in every operation by holding workpieces securely during machining, drilling, or assembly processes. Their long, flat, and narrow shape allows them to wrap around or against the workpiece, applying steady pressure without causing damage. Strap clamps use a screw or bolt to convert the applied toque into a clamping force, which is exerted through a fulcrum and beam setup to ensure the workpiece is firmly in place.
Why Do You Need to Calculate Clamping Force?
When using strap clamps in your operation, it’s essential to accurately calculate clamping force. It ensures the stability and security of the workpiece during machining or assembly, preventing movement that could lead to inaccuracies or damage. Proper force calculation also helps maintain the integrity of the workpiece, avoiding excessive pressure that could cause deformation. Finally, understanding the required clamping force helps you select the appropriate clamp size and type, optimizing both the safety and efficiency of your operation.
The tables below outline the clamping force and tensile force recommended per stud size, in both inches and metric units. Note that the recommended torque is based on a clean, dry clamping stud that is torqued to approximately 33% of its 100,000 psi yield strength (2:1 lever ratio):
Inch
| Stud Size |
Recommended Torque* (ft-lbs) |
Clamping Force (lbs) |
Tensile Force in Stud (lbs) |
| #10-32 |
2 |
300 |
600 |
| 1/4-20 |
4 |
500 |
1000 |
| 5/16-18 |
9 |
900 |
1800 |
| 3/8-16 |
16 |
1300 |
2600 |
| 1/2-13 |
38 |
2300 |
4600 |
| 5/8-11 |
77 |
3700 |
7400 |
| 3/4-10 |
138 |
5500 |
11000 |
| 7/8-9 |
222 |
7600 |
15200 |
| 1-8 |
333 |
10000 |
20000 |
Metric
| Stud Size |
Recommended Torque* (ft-lbs) |
Clamping Force (lbs) |
Tensile Force in Stud (lbs) |
| M6 |
4 |
500 |
1000 |
| M8 |
9 |
900 |
1800 |
| M10 |
20 |
1500 |
3000 |
| M12 |
35 |
2200 |
4400 |
| M16 |
84 |
4000 |
8000 |
| M20 |
165 |
6300 |
12600 |
| M24 |
283 |
9000 |
18000 |
Clamping Force Calculator
You can also determine the proper strap clamp force with our easy-to-use calculator. Whether in inches or metric units, you can input the stud major diameter, torque, coefficient of friction, and lever ratio to determine the correct tensile force and clamping force. Using your own measurements instead of exploring a table ensures you use the most accurate clamping force for your application, reducing the risk of workpiece movement or deformation.
Learn More About Strap Clamps with Carr Lane Mfg.
Because of their simple design and ease of use, strap clamps are a popular choice in many applications, including woodworking, metalworking, and other manufacturing operations. While knowing the proper clamping force is important, it’s also essential to know the ins and outs of strap clamps, including how they work, the types available, and the additional fastening elements used. To master the art of strap clamping, explore Carr Lane Mfg.’s comprehensive guide.
Read the Strap Clamp Guide
View Guide