From: JB Ventures BV (info@jbventures.nl)
Date: Wed Nov 20 2002 - 10:35:46 EET
missed a word in my reply :
'are specific affected by warpage' must be 'are NOT specific affected by warpage'
(what a difference one word can do
JB
----- Original Message -----
From: JB Ventures BV
To: Scott Tilton
Cc: RPML
Sent: Tuesday, November 19, 2002 11:23 PM
Subject: Re: Stratasys - SPT - Slow Prototyping
Guess it's my turn again ...
How does it work with FDM? For PolyCarbonate, buildvolume temp is 145 degrees C, with a tiptemperature (model) of about 360 degrees C(ABS = buildvolume about 80 degrees C)
I assume the build chamber is also heated in an FDM machine to somewhere up near the melting point of the material. True? Nip, See prev.
Is there a gradual, programmable cool down stage for a FDM with some sort of convection currents to assure even cooling? Parts can be taken off directly without any damage when machine finishes it's job
Do the parts suffer from warping problems because of thermal gradients? FDM Parts do shrink but tends to be lineair as all plastics do due to temp. change. Parts are specific affected by warpage because buildvolume temp is (a lot) lower than meltingtemp. of modelled material. Only on large (+75mm.) right upstanding (Z-direction) flat thinwalled product (<0,7mm) deformation occurs due to warpage (packaging products). Typical problem we experience in these cases is the fact that resonance of both pressure- and vacuumcompressors in the machine causes also surface deformation (FDM Titan). Constructing a separate compressorbox would end this problem ...
I would guess that this is dependant on the specific part geometry. Prev.
Thin wall, solid mass . .mix of the two. Wall thicknesses from 0,5mm can be build on 0,17mm layerthickness (0,8mm on 0,25mm layers). Building as thick as you want is possible hower wallthickness must fit the buildvolume ;-)
Jorn Berends
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