RE: SLA 250 laser remelts.

Date: Tue May 21 1996 - 21:53:19 EEST

>what happens to a part if you have to do a re-melt in
>the middle of a
>build, such as of your laser power drops 10-15mws from
>around 20mw to a
>low of 5-10mws?



I had that very thing happen to me (the numbers were
different...35mW dropped to 9mW). I did a double
re-melt, returning the power to 35mW and continued the
build without incident. What happened to the parts?
Well, they finished building ok and the parts LOOKED
fine...but the real question is were they as accurate?

This leads to my question, how often are you SLA
operators performing calibration tests such as Window
Panes and Christmas Trees? How much do you let the
laser power change before recalibrating? Do you have a
regular calibration day regardless of, or in addition to
power drops? What other things do you let influence
your decision to recalibrate? Do you always run Window
Panes before Christmas Trees?

As far as the question of re-melts and laser life. My
last two lasers have not lasted as long as earlier
lasers (~3000 compared to 5000 and 6000 before). My
most recent laser (3-1/2 months, ~1300 hrs) has already
had atleast 4 double re-melts, the first one was
required at only 210 hrs, but it does seem to run at a
consistant power until it does a dramatic drop.

Beth Israelnaim
Becton Dickinson Research Center
(919) 990-2153

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