UHMW and humidity absorption
UHMW and humidity absorption
(OP)
HI,
I have used UHMW-PE for the manufacturing of three parts, one that is 7 inch wide by 24 inch long and 3/8 thick. Inside of this parts I have two holes of 5"1/2 diameter. then I have two other identical parts, who looks like donuts that inserts in this hole with the same thicknesses than the first one. They have a 0.010 press fit tolerance when inserted in the hole.
Since UHMW-PE is reasonably malleable we have no problem inserting the parts manually. The problem is that these parts are used in a tempered environment at 4°C with a lot of humidity. And after a couple of weeks we are no longer able to insert the parts manually. So I wonder if it's because the material absorb some humidity and then he changes dimensions.
What do you think about it? Am I right? what type of plastic material who is FDA approved that would be much stable?
Thanks in advance for any help.
Patrick
I have used UHMW-PE for the manufacturing of three parts, one that is 7 inch wide by 24 inch long and 3/8 thick. Inside of this parts I have two holes of 5"1/2 diameter. then I have two other identical parts, who looks like donuts that inserts in this hole with the same thicknesses than the first one. They have a 0.010 press fit tolerance when inserted in the hole.
Since UHMW-PE is reasonably malleable we have no problem inserting the parts manually. The problem is that these parts are used in a tempered environment at 4°C with a lot of humidity. And after a couple of weeks we are no longer able to insert the parts manually. So I wonder if it's because the material absorb some humidity and then he changes dimensions.
What do you think about it? Am I right? what type of plastic material who is FDA approved that would be much stable?
Thanks in advance for any help.
Patrick





RE: UHMW and humidity absorption
holes? Are the donuts also plastic
and attached to a plastic part?
Why are you pressfitting these .010
tight? Could one be a pressfit and
the other to size? I do think humidity
would change the parts. It might be
cheaper to have a second jig for the
extreme temperature range.
RE: UHMW and humidity absorption
Patrick
RE: UHMW and humidity absorption