smc molds

[giocamb]

Good day to all

I have a problem with molds for the smc.
our client has sent us moulds for smc, we are discussing for retreats to be applied,
the problem is who has to make the molds says one thing and who gives the raw material to print tells another without getting to a soluziaone, I tell you.
the SMS supplier says:
smc material cold mold to cold part shrinkage : 0.000009 in/in
practically no withdrawal,the problem however is that the mold being made of steel and at 150 degrees has an elongation(coeficent of steel elongation is 0.000012) on 1000mm stretches of 1.5mm.
molds with details to print vary from a length of 1000mm to get to lunchezze of 2000mm, the problem that not withdrawing and that there are tolerances of +o-1mm, the smc once printed does not withdraw practically nothing according to me the withdrawal to be applied in the design is a negative withdrawal of the -0.15% for the mold from 1000mm and for the mold from 2000mm one -0.3%.
do you think if there is someone who has done or does molds for the smc is correct my interpretation?

thanks guys and good work

 

[TECNOMODEL]

can you post the material card?

if you can also a drawing/image of the piece.

Those tolerances on a printed piece seem a little tight for that size.

 

[giocamb]

 

[TECNOMODEL]

in the tab see polymerization shrinkage 0.00008 in/in expansion.

gives me the idea of a positive retreat

 

[giocamb]

I also agree, but the customer tells me that once I print the piece and pull it out of the mold does not withdraw because practically that value on one meter is 0, but the problem is that if I cut a mold without withdrawal and then the scaldo to 150° on one meter dilated of 1.5mm not withdrawing sonbo already out tolerance...the withdrawal on mold injection, that they are of the thermoplastic that of the Pu or pdcp just

 

[TECNOMODEL]

I also would have reasoned as you did, but I confess that I never found myself in such a situation.

an idea would be to make a pilot mold to verify the retreats.

 

[giocamb]

already, but we also told him to try with a stupid piece with the same material and check after 24 hours if he is withdrawn and then make a dimensional relief of the mold and piece. .

bho we will be seeing but I am glad that my reasoning is not wrong, because you know tamte times there are also doubts that then you risk doing some crap and then they are pains.