**Next message:**Lightman, Allan J.: "Re: SLA scan speed vs. laser power"**Previous message:**Nagendra H. V. (proj BGM): "Re: SLA basics: a question"**Maybe in reply to:**ralott@CCGATE.HAC.COM: "SLA basics: a question"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ] [ attachment ]

*>Rick,
*

*>Elaine Hunt has informed me of your question.
*

*>
*

*>From Rapid Prototyping & Manufacturing Fundamentals of StereoLithography
*

*>by Paul Jacobs (SME, 1992):
*

*>
*

*>V = P/(Eo h)
*

*>
*

*>where V is the scan speed (cm/s)
*

*> P is laser power (mW)
*

*> Eo is energy delivered at the surface of the vat (mJ/cm^2)
*

*> h is the line spacing (cm)
*

*>
*

*>This of course is the theory.
*

*>
*

*>Using another equation, from the same book:
*

*>
*

*>Cd = Dp ln(Eo/Ec)
*

*>
*

*>where Cd is the cure depth (mils)
*

*> Dp is the depth of penetration (mils)
*

*> Ec is the critical energy (mJ/cm^2)
*

*>
*

*>and combining it with the first equation to get:
*

*>
*

*>V = P/[Ec h exp(Cd/Dp)]
*

*>
*

*>gives an equation that can be used to verify the performance of the SLA.
*

*>
*

*>Given the surface area of a layer, and the line spacing h, and the time
*

*>required to draw one layer, V can be calculated experimentally. Ec and Dp are
*

*>in the resin file. Cd can be considered the layer thickness plus overcure.
*

*>Compare P from the monitor to V to verify the first equation.
*

*>
*

*>The performance of our SLA 250/50 seems to correlate nicely with first
*

*>equation.
*

*>
*

*>Douglas Taft
*

*>Graduate Assistant
*

*>Department of Chemical Engineering
*

*>Clemson University
*

*>
*

*******************************************************************

Opinions, suggestions, and other controversial matter VOID where prohibited.

******************************************************************

Elaine (Persall) Hunt, Director

Clemson University Laboratory to Advance Industrial Prototyping

206 Fluor Daniel Bldg. Clemson, SC 29643-0925

864-656-0321 (voice) 864-656-4435 (fax)

persall@ces.clemson.edu

http://design.eng.clemson.edu/rp/persall/elaine.html

**Next message:**Lightman, Allan J.: "Re: SLA scan speed vs. laser power"**Previous message:**Nagendra H. V. (proj BGM): "Re: SLA basics: a question"**Maybe in reply to:**ralott@CCGATE.HAC.COM: "SLA basics: a question"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ] [ attachment ]

*
This archive was generated by hypermail 2.1.2
: Tue Jun 05 2001 - 22:39:44 EEST
*