Which grade of DELRIN did you try? How did the DELRIN fail: tension, flex fatigue, creep, chemical degradation, high temperature, was there a lubricant, abrasion, etc.?
Regards,
Ernie
I need to find a plastic that could act as a small leaf spring. I tried
> Derlin but it failed very quickly. I am kind of stuck on a project I am
> working on and might have to give it up if I can not find the right
> material. I need it to act as a return spring for a key arm. I would
> like to make the arm and the spring out of the same material and have it
> be molded or laser cut.
>
> Thanks in advance.
>
As Rolf Wissmann stated in his reply, DELRIN 100 is the best for applications involving flex.
Your note said that the DELRIN failed very quickly. A quick failure can result if the DELRIN piece has stress risers machined or molded in, for example, if the piece was cut with a saw and scratches not polished out. The other possibility is too high stress on the DELRIN. Flex fatigue life has a strong dependence on the stress (force per unit area) applied during bending; DuPont can probably supply flex life vs. stress. I "guesstimate" that if the part failed very quickly (say less than 100 cycles) than the applied stress had to be at least 5000 psi; based on this guesstimate, for the 0.0625"x0.0625" part, the force would have had to be at least 20 lbs.
If you are relatively sure that the physical condition of the test piece was OK, than you may want to consider redesigning the part to reduce the stress on DELRIN. You could also try something like DELRIN 100ST, which has much lower modulus, and for the same amount of bending will be subjected to much lower stress, but will also exert less return spring force. Or, you can consult a plastic part designer, who should be able to design a new part geometry. You may want to consult with DuPont.
Correct. BUT, the morphology of Delrin*100ST is very poor (laminar, = onion-like!) due to a relatively poor compatibilizer! I wouldn't touch 100ST. Sorry = Ed!
"Ernie" schrieb im Newsbeitrag = news: snipped-for-privacy@corp.supernews.com...
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