SL resin perishability

From: Guy Allen Brady (galbrady@engin.umich.edu)
Date: Fri Sep 13 1996 - 17:12:26 EEST


I have a question regarding the perishabilty of stereolithography
resins, particularly SL 5170 epoxy.

As resin is used and replenished with new resin as needed, at what point
do users "purge" the old resin and start with 100% new resin? Does it
ever need to be "refreshed"? If so, what criteria is used to determine
when this needs to be done? Is it too much crap at the bottom of the
vat, viscosity measurements, the "feeling" of the operator, part
quality-strength, rate of resin usage, laser hours, cash on hand to buy
resin....etc.

Is the "old" resin filtered and resued at some point??

Or, are there cases where new resin is added continuously without any
purging process???

I would appreciate any comments on this issue. It would be best to get
both 3D's Resin R&D folks (or equivalent) as well as anecdotal evidence
from typical users.

Thanks, all.

-- 
          G. Allen Brady  --  Graduate Research Assistant          
Materials Science and Engineering - The University of Michigan     
2219 H.H. Dow Bldg.  2300 Hayward Street   Ann Arbor, MI  48105
work: 313/936-0177   fax: 313/747-4807   email:
galbrady@umich.edu          
           http://www-personal.engin.umich.edu/~galbrady



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