Torque Values for Brass Fasteners

[Webber]

Does anyone have a torque value table for brass fasteners? I am specifically looking for 5-16"-18 brass to mount a ground lug to the stud. I would like the preload and finish torque values.

 

[MEisme]

For steel fasteners, the torque value is that which results in fastener tension of nominally 75% of the yield strength of the fastener material. I'm not sure if this is recommended for brass (or other nonsteel fasteners.)

Phil

 

[235]

http://www.efunda.com/designstandards/screws/screws_intro.cfm

 

[tothepoint]

Identify the yield strength of the brass fasteners you're using, and multiply this by the Tensile Stress Area of the 5/16" fastener. This is the axial force at bolt yield. Determine your factor of safety against assembly yield (ex. 75%) and reduce the bolt force by this amount. This is your assembly bolt load. Torque = Assembly Bolt Load(lb) x nut factor x Nominal Bolt Diameter(in)= in=lb
The nut factor will vary from 0.10 - 0.4 depending upon many variables. With new fasteners, anti-seize thread lube, and hardened flat washers (or smooth flange) the nut factor will be ~0.18.

 

[Webber]

Thank you all for your replies.

 

[abdul]

Hi webber,

Here is a very simple method of determining the optimum torque. First, get a torque wrench, and install the brass bolts into a suitable temporary joint. Add the nut and torque slowly, adding force increments until the bolt thread is sheared, or the threads shear.

Now you know the torque required to achieve the ultimate shear strength of this specific bolt. For a safe working-margin, just use 60% to 70% of this value, when torquing your bolts in your actual application.

This method can be used with any bolt material. However, you still have to confirm that the bolts can handle the loading applied in service.

Good luck,

abdul