High Load Living Hinge

[BML]

I'm wondering if anyone can point me in the right direction, if there is one. I need to make a living hinge that flexes easily but has high shear and tensile strength. This part will be subjected to several hundred cycles, and will need to withstand tear-type loads of at least 650 lb per 12 linear inches. The material would preferably be extrudable, but molding is okay too.

Thanks!

 

[patprimmer]

Polypropylene makes the best live hinges, but must be injection moulded to produce a strong hinge.

I have no idea what actual strength can be obtained, but the PP across the hinge will be stronger than the PP in the rest of the moulding due to the highly oriented molecules across the hinge. the properties of the material across a properly designed and moulded live hinge will be between the properties of a moulding and a fibre.

Regards
pat pprimmer@acay.com.au
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[Pud]

Hi BML

Is it just a hinge (i.e. a "bendy bit") you need or do you need two parts (of the same material) to be connected with an integral hinge? You also make no mention of required cycles before failure or environmental conditions?

If you just need a "bendy bit" then you might try sheets of polyurethane (v. high tear strength), or some of the polyester elastomers (e.g. Hytrel by Dupont, Arnitel by DSM and no doubt others too numerous to mention...)

All the above should be available in extrusion and inj moulding flavours.


Rgds


Harry

 

[plasgears]

Nylon 6 makes a tough structural member in bending. I had a gear that had to tough it out without circuit protection and stall protection. It would not break; it would flex in a surprising manner. I got the advice to change matls from a mfr.