Single use - Plastic Hinge? 1

[ttx]

Hi,
We are designing a plastic enclosure to encase a circuit board. The part will be injection molded - possibly ABS or Cycloloy. The part is a "clam shell" design that is intended to snap shut once and not be reopened. We have been struggling a bit trying to determine if the hinge design that we have will work. There seems to be a fair bit of information on the Web regarding living hinges-but not single use hinges. We definitely don't want a living hinge and don't want to use Polypropylene or Polystyrene. Does anyone have any insight to share on single use hinges? Any information or sharing of past experiences would be appreciated.

Thanks.

Best Regards,

JW
Tactex Controls Inc.

 

[patprimmer]

I have no actual experience on this, but I would expect a well designed hinge in ABS to work through one cycle of 180 deg.

I would expect a good design to have a thin hinge of reasonable length across the land and the land to be blended in to the normal wall section with reasonable radii.

I don't know how ABS (or any other amorphous resin) reacts to one cycle of the hinge immediately after ejection, and while still quite warm.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
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[patprimmer]

I have since spoken with moulders who have succesfully used ABS live hinges that work for limited use applications. They claim the design has to be good with thin hinge, long land and good notch free transition of land to main section of moulding.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[ttx]

Pat,
Thank you for doing the research!
I am afraid that I am not familiar with all of the terminology....
Could you elaborate a bit on the term "long land"?

Thanks,

JW

 

[patprimmer]

The thin bit that will do the actual bending.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.