Re: SLA basics: a question

From: Elaine Persall (
Date: Thu Jun 19 1997 - 17:01:25 EEST


>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
>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)

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