Aluminium threads failure 2

[Pina87]

Hi
I need to fasten a force sensor to an aluminium plate of 20mm thickness. The manufacturer of the sensor provides that it should be fastened with two bolts M12 12.9 with a torque of 130Nm onto a plate made of stainless steel (20mm). Because of the weight I can only use an aluminium plate.

My question now is: how to I know if the threads in aluminium will withstand the torque of 130Nm.

Thnx in advance

 

[Pina87]

Sorry I meant the friction coef. betwen the head of the bolt and the sensor. There is no nut involved.

Sorry

 

[gadkinsj]

Speaking of nut. Can you just forego threading the aluminum plate and put a nut on the back side of it with a washer?

 

[Pina87]

Jap, this is what we're going to do now, because it looks like we don't have any other choice.

Thanx for all the information, they were realy helpful.

 

[dinjin]

If so, use a special larger O.D. washer to ensure that you do not have too much pressure under the washers.

 

[Pina87]

We are thinking about using a flat head bolt (DIN 7991), because we don't want any unevenness on the upper side of the plate. So I need to figure out if the aluminium plate will sustain the pressure under the head of the srew.
Are there any special formulas for calculating the pressure for this kind of bolts or can I just take the same one like for a normal bolt with a washer.

Thnx

 

[desertfox]

Hi Pina87

I would do a bearing stress calculation as you describe.

desertfox

 

[TVP]

VDI2230 defines this property as the "limiting surface pressure", with the symbol p[sub]G[/sub]. Wrought aluminum alloy AlMgSi1 F31 (3.2315), similar to 6061-T6 in North America (UTS 290 MPa, YS 250 MPa), has a value of p[sub]G[/sub] = 260 MPa. The same alloy at somewhat lower strength (UTS 260 MPa, YS 200 MPa) has p[sub]G[/sub] = 230 MPa. Wrought alloy AlMg4,5Mn F27 (3.3547), similar to 5052 (UTS 260, YS 110), has p[sub]G[/sub] = 230 MPa.

 

[Tmoose]

Will you be tightening the nut or the screw?

 

[Pina87]

The nut.