Factors in consideration
The target torque vs the capacity of the impact wrench or pulse wrench
The joint condition
The type of torque tool to be usedTorque tool specification vs target torque tool and joint hardness
How many seconds to finish the job
Bolting sequence control and stages for tightening the bolt
Traceability for job responsibility
Joint Hardness (Soft /Hard) | Target Torque | Suggested Capacity | Seconds (s) for bolting | Torque Capacity (90 psi) |
S ( Soft ) | TT | 1.5 – 2 TT | t- 5 s | T5 ≧ 2 x TT |
t- 4 s | T4 ≧ 3 x TT | |||
t- 3 s | T3 ≧ 4 x TT | |||
t- 2 s | T2 ≧ 5 x TT | |||
H ( Hard ) | TT | 1.5 – 2 TT | t- 5 s | T5 ≧1.5 x TT |
t- 4 s | T4 ≧ 2 x TT | |||
t- 3 s | T3 ≧2.5 x TT | |||
t- 2 s | T2 ≧ 3 x TT |
How to select the proper size of the impact wrench
Before bolting, refer to the chart above, think about the target torque and how many seconds it takes to achieve the target, the airline preparation such as the air hose size, the hose length as well as the hardness of the joint, etc. for selecting the proper capacity of the impact wrenches.
Please note that most of the nominated torque capacity of the impact wrench is the residual torque measured on the torque tester after tightening the bolt for 5 or 10 seconds under 90 psi air pressure.
Working example
If tightening a hard joint to 100NM within 2 seconds is expected, selecting an impact tool with a maximum output torque capacity of 300NM within 5 seconds is recommended.
If tightening a soft joint to 100NM within 2 seconds is expected, selecting an impact tool with a maximum output torque capacity of 500NM within 5 seconds is recommended.
How do you select the right torque transducer?
Selecting the transducer with a specified torque capacity of 1.5 to 2 times the target torque is recommended.
If the target torque is 100Nm, the torque capacity of the transducer will be 150Nm – 200NM
If the target torque is 750Nm, the torque capacity of the transducer will be 1000Nm – 1500NM
ZIPPTORK Wireless torque transducer can be used on air torque tools for
Continuous drive clutch type tool such as an air pulse tool, air screwdriver, or pneumatic torque multiplier
Discontinuous drive impact type torque tool such as an air impact wrench or oil pulse wrench