When Would You Use a Pem Clinch Nut Over a Straight Thread? 4

[Zibraz]

When designing sheet metal, what are the considerations made to decide whether you will use a pem clinch nut or jus a normal thread?

Typically, I felt that pem nuts are always better than threads in aluminum sheets, but Steel sheets are much stronger and stripping a thread is more difficult, and hence the pem nut isn't needed.

 

[desertfox]

Hi Zibraz

Depends how thick the sheets are, you might not get the thread engagement you require in thin steel sheet and therefore a PEM nut might be better.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[Zibraz]

Hey Desertfox.

Yeah I kind of guessed that might play into it. So it's just deciding whether the sheet is thick and strong enough to cope with the torque of the screw. We usually deal with aluminium and steel sheets between 1-3mm depending on the application and forces of the overall design.

I was just a consensus on when to choose a pem over a normal thread. I have had issues with PEM nuts falling off from the supplier, so I like to avoid them where possible, but aluminium threads in sheet can sometimes be easily stripped. It's a trap off.

 

[SnTMan]

Trap off is right

Regards

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[drawoh]

Zibraz,

Does your punch press do tapped holes?

What will it cost you to tap holes, and what will it cost to install the much stronger inserts?

Have you verified that your steel sheet is soft enough to accept press-in inserts?

--
JHG

 

[3DDave]

I'd be asking PEM for some technical support to see what the problem is. I expect they have seen most every cause for failure.

 

[desertfox]

Hi Zibraz

I wouldn’t consider trying to thread sheet 3mm thick because you would be lucky to get a single thread in that thickness. To consider the thread strength you really need to know the external loads on the jointed parts.
I agree with others who suggest you talk to PEM about the failures you have experienced.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[BrianPetersen]

Automotive here. Tapped holes are only ever used in cast parts that are going through a CNC. For stamped steel parts it's either weld nuts, or clinch nuts of some sort, or self-tappers, or plain hole + screw and nut (only when necessary).

 

[drawoh]

Zibraz,

You may be able to use those clip-on sheet metal fasteners. They are not limited by the hardness of the steel sheet.

A good rule of thumb when not using nuts of any sort is that the thing with the female thread is many orders of magnitude more expensive than the thing with the male thread. Design threads accordingly.

--
JHG