Manual Torque Wrench vs. Impact Wrench
Manual Torque Wrench vs. Impact Wrench
(OP)
This question applies to bolted structural connections. Can a manual torque wrench apply the same tension to a fastener as an impact wrench qualified on a skidmore? (Assume bolts are to be tensioned to 39,000 psi.) In other words, does a properly operating impact wrench apply more effective rotational force due to its "dynamic" impact action?






RE: Manual Torque Wrench vs. Impact Wrench
Any properly working machine will be more effective than manual work.
One of the big issues is with too much torque. It is very common to over-torque bolts in a connection and after a while the over torqued bolts will fail and pop off. Or, they may pop off while QA/QC with a manual torque wrench.
There are those impact wrenches with auto shut-off but I've not found them to be reliable. And there is a multitude of indicator bolts on the market too.
Regards,

Qshake
Eng-Tips Forums:Real Solutions for Real Problems Really Quick.
RE: Manual Torque Wrench vs. Impact Wrench
I'm not prepared to assert that the impact wrench and the manual wrench leave the bolt in exactly the same stress state, but the calibrator allows you to establish a correlation.
If the bolt knew the difference, S-W would be out of business.
On the other hand, an impact wrench depends on the dynamics of the joint.
Example: I was getting a flat fixed at a tire shop right before closing, and all the lifts were busy. I started jacking the car with its own cheapo scissor jack, and the tire tech came up with the bright idea of zipping the jack up with his impact wrench. This was a big wrench in good repair, perfectly capable of breaking off a wheel stud. It hammered away like crazy, but it couldn't lift the car as fast as I had been doing it with the jack handle. It could barely lift it at all until the load got serious. We were both surprised.
Mike Halloran
Pembroke Pines, FL, USA
RE: Manual Torque Wrench vs. Impact Wrench
RE: Manual Torque Wrench vs. Impact Wrench
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Manual Torque Wrench vs. Impact Wrench