Stripping of threads

[Drej]

Dear all,

I have a problem with threads being stripped out of a tapped hole. Simply put, there is a block which has threads tapped into it. A large spacer (another block) fits on top of this block and is secured to it by a shanked bolt. Only the top quarter of threads are apparantly being stripped out of the block after some short time in service (1 month). There are two axial (only axial, no bending) loads on the bolt which are (1) the preload of the bolt and (2) another axial load from the block. I am trying to calculate from these axial loads whether the threads will be stripped out but I can't find any literature on this. Is it a simple task or not?

Appreciate your advice.


-- drej --

 

[Lutfi]

It sounds like you are applying a tensile force that is greater than the parent material can handle. You want to consider changing the material or annealing it to higher strength.

Machinary handbook has excellent step-by-step design procedure for threaded materials.

You can re-thread the parent material and install a Keenserts.

I also have a step-by-step sheet on how to compute the strength of threads. If you give me you fax, I can send it to you.

Regards,


Lutfi

http://www.cdeco.com

 

[Drej]

Lufti - thanks for the advice. Unfortunately I don't have machinery's handbook, but I'd like some theory including a set of equations which I can then apply to this job. Obviously something like machinery's but on the web (or off of the top of someone's head if possible).

Cheers.

 

[Lutfi]

Give me your e-mail address and I will scan and e-mail you one worked out example. Also, if you tell me what is the material of the bolt (fastener) and the parent material, I will scan the required mechanical properties and send them for you.

Regards,



Lutfi

http://www.cdeco.com