PEM Stud proof load

[varistor]

Hi all, hoping someone can help. This is probably quite simple, but today brain like jello!

Usually if I am to do a quick hand calculation on fixing products to structures I use the following approach;

Firstly determine all max tension and shear forces

So, example M6 Bolts Grade 8.8 Nickel Plated Steel
Proof Load of bolt = 11500N
Tighteneing Torque = 11.7Nm @ 85% proof load

Bolt Preload = 0.85 x Proof Load
Shear capacity = (Bolt Preload - Max Tension) * Friction Coefficient

Rf connection = Shear capacity / Max Shear


What I am unsure about is the proof load for an M6 Pem Ttype push stud. The datasheet seems to suggest a max tightening torque of 5.9Nm, which is considerably less than an M6 bolt (for obvious reasons), but how do I calculate the proof load

D

 

[MikeHalloran]

Ask Pem?


Mike Halloran
Pembroke Pines, FL, USA

 

[TVP]

varistor,

The proof load is meaningless for clinch-type fasteners, because it is the clinch area that is the weakest, not the threads or the shank. As a first pass, you can use the equation T = kDF where T = torque, k is a friction factor, D is the major diameter and F is the preload. Since you already know T = 5.9 Nm maximum, solve for F. k is usually between 0.1 and 0.2 depending on the coatings and lubricants involved.