Captive screw

[tanner78]

Hello,

I am designing an item with 4 screws M6 fastened on 4 through holes obtained on aluminum bores (height = 12 mm) at the respective ends of a flange.
I am evaluating the category of captive screws since for handling reasons I would like to tight the screws on the holes so as to keep them fixed, even e.g. if I turn the item upside down.
Since the holes are through and not threaded, I should use a fastening sysemt such as a fischer plug system (like wall plugs), but the bores are too short (12 mm) for such plugs. I would like to avoid complications such as cotter pins and other systems difficult to remove after final assembling of the item.
Can you suggest me some commercial screws or systems that help me in this way?

Thank you very much for your help.

 

[CoryPad]

Try Rifixx from Ribe:

http://www.ribe.de/sites/default/files/ckeditor_files/WNejRvtH9uMZy7yX45BH.pdf

 

[CoryPad]

Acument has similar ones too:

http://www.acument.com/products/engineered-specials/bolt-sleeve-assembly/

 

[ornerynorsk]

A reduced neck screw with a partially thread hole does the trick nicely.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[KENAT]

We routinely use what ornerynorsk mentions, avoids needing captive washers etc. so good 'Design For Assembly' at the expense of slightly greater cost of partially threaded holes.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[tanner78]

Thanks to all for your replies.

Partially threaded hole is definitively a fine and cheap solution, but if a completely through hole is requested as in my case, I suppose one of the captive screws suggeste in the links by CoryPad would fit...

 

[CoryPad]

tanner78: note that you need a waisted screw (shank diameter < screw thread minor diameter), which is not always available in every configuration.

 

[KENAT]

Well, you can create your own if need be by turning down a std screw, but that may not be cheap and might have other potential issue.

I think it's Accurate Screw Machine that will allow you to custom spec a 'captive panel' screw.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[CoryPad]

Correct Kenat:

http://www.accuratescrew.com/captive-screws.aspx

 

[geesamand]

http://www.savetix.de