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Torque required to develop 1323 N (297#) load
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Posted by: calrgl99 ®

04/22/2005, 08:52:44

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I need to do a tightening test on a battry hold down bar. The bar is held down with 2 M6 nuts. I must apply a load of 1323 N to the top of the battery to verify the amount of deformation that will occur to the battery and bar contact surface.
What is the torque on one nut in Ft.# or In.# required to apply a load of 1323 N (297#) to the top of the battery surface?
Equal resultant torque will be applied to both nuts during test.







Modified by calrgl99 at Fri, Apr 22, 2005, 10:03:08

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Re: Torque required to develop 1323 N (297#) load
Re: Torque required to develop 1323 N (297#) load -- calrgl99 Post Reply Top of thread Forum
Posted by: Cragyon ®
Bart
04/22/2005, 13:45:11

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Using the old-fashioned torque force calculator here on engineers Edge /torque.htm.

Assuming each screw has an equal influence on the applied force, I calculate 7.1 in-lbs each screw.







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Re: Torque required to develop 1323 N (297#) load Smile
Re: Re: Torque required to develop 1323 N (297#) load -- Cragyon Post Reply Top of thread Forum
Posted by: calrgl99 ®

04/25/2005, 10:38:20

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Thank you for the information. I have, and will again review the torque force calculator, but I had our test lab set up a fixture to get actual torque and load values. Fixturing the actual parts and attaching a loadcell to digitally read the load, we determined that the actual load at 1328 N requires an average of 3.8 N*m (2.8 ft. lb.) torque. This test was performed 4 times, and was applied with one screw. The screws (nuts) will have equal influence of applied force when applied for our battery hold down torque test.
Thank you very much for your response.






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Re: Torque required to develop 1323 N (297#) load Smile
Re: Re: Torque required to develop 1323 N (297#) load -- calrgl99 Post Reply Top of thread Forum
Posted by: Cragyon ®
Bart
04/25/2005, 13:04:22

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I'm sure you are aware that the calculations associated with torque is, at best only an estimate. Factors, such as lubrication, fastener size, surface roughness, number of times a fastener/thread has been torqued, temperature and dissimular materials can complicate the resultant torque applied force. Also, release or removal torque tends to different than installtion torque, even only a few moments after the torque had been applied.

Torque design should be viewed as just that, an estimate. Fortunately, installation forces are forgiving. For precision control of applied force due to torque, strain gauges or constant force springs may need be considered.







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