Thread engagement length question

[JARTECH]

Hi, I'm new here. I was searching for how much pulling resistance force per mm or inch has a stud engaged in aluminum, but all I can find is about thread stripping resistance, that I think is torsional torque. Please any help here is very appreciate. Thanks for your time !

 

[patprimmer]

How do you pull a thread to fail without stripping it.

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[Metalguy]

Internal thread strength depends on several factors--YS and UTS of material, thread fit, and the stiffness/rigidness of the material surrounding the threads.

A steel bolt can break in a hard plastic block if there are enough threads engaged AND if the block is thick enough to resist springing away (hole deformation).

"I'm that dog who saw a rainbow, only none of the other dogs believed me." from "Kate and Leopold"

 

[JARTECH]

I think that I wasn't accurate. I was looking for a M5-M8 stud, not a bolt, that will engaged like 13mm, in auminium. The aluminum specs can be taken as cylinder head material. The stud will be grade 8 equivalent, and what I want to know is #1 How much tension force will resist and #2 how much torque I can apply to the nut that will go on the stud( assuming that the portion in aluminum was the one that will break) Some calculations really will help. Thanks guys !!!

 

[lugnuts67]

A fastener works like a coil spring. As you tighten the bolt or nut on a stud, it will stretch and generate a clamping load. The key to correct tightening of the fastener is to tighten it until it is just slightly less that the fasteners elastic limit. To do it dead on you must identify the material of the stud and find out what that limit is, then use a dial indicator and tighten until just shy of the materials elastic limit. If you must torque it down, remember that the torque is measuring a resistence to movement and will be effected by friction. Use a lubricant and tighten the nut or nut and washer if one is going to be used several times to burnish it in dry a couple of times and then use libricant on the final tightening. ARP recommends fully torquing each fasterner 3 times with moly lube.
But that wasn't your question was it? You wanted to know how much pulling force you could put on a 13mm depth M8 stud in say A356 aluminum that had been heat treated to a T-6 spec (common aftermarket aluminum cylinder head). Another bit of information required would be thread count (corse/fine) or thread pitch (basically the distance from one thread to the next on metric threads). Each one of those threads engauged distribute load and you need to determine what is least; the fastener material elastic limit by diameter, the aluminum load limit disributed by number of threads or the nut's (no, not mine) load limit.

 

[Warpspeed]

Have you thought about the possibility of installing a threaded insert into the aluminium ?

 

[JARTECH]

Thanks for the inputs, they are really appreciate. To be more exact, the thread count and the thread pitch are like the 10mm hex bolts that most japanese cars had it their valve cover. Since Is not bad idea the insert, I dont believe that it is a solution in this particular case. For this case, I was more focused in the design parameters and calculation, more that in numbers. Thanks for read this message.