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Burn-out cycles for RP


#1

James,

Speaking of burnout cycles, How about the best for RP resins? 

The cycle I use for Perfactory and Viper models is as follows: (all
in Fahrenheit) flask into cold oven; raise temp 600 degrees per hour
to 300-hold for three hours; raise temp by 600 degrees per hour to
700-hold for 2 hours; raise temp by 600 degrees per hour to 1000-hold
5 hours; raise temp by 400 degrees per hour to 1400 (to 1450)-hold 4
to 5 hours; drop temp down as quickly as kiln will cool to your
holding casting temp (casting temp dependent upon the metal being cast
and model design) hold at casting temp 1/2 hour to 1 hour to stabilize
temp.

With ramp times and holding times this works out to be about a 17-1/2
hour burn-out cycle. Because of the high temp needed for the RP
models you need to use either a platinum investment or R&R’s
Ultravest-Maxx. I use the later with excellent results. (as always
said…not associated with the company, just happy end user of their
product).

Using the above burn-out schedule and the specified investment
material, you will get very clean, smooth castings from both
Perfactory models and Viper models, provided you do a compressed air
blow out of the mold prior to casting…I use 30 pounds air pressure
to do this, holding the flask with button hole facing down and
blowing across the button hole to create a Venturi effect sucking any
remaining dust out of the mold.

Paul D. Reilly


#2

Paul,

Did you run the Perfactory parts through a flash-oven (which blasts
them with high-intensity light) before burning them out? That’s
supposed to cure the resin that remains inside the parts uncured
through the build process, promote melt-out, reduce ash formation,
and speed up the burnout cycle. 17.5 hours seems like a long time.
Are these fairly big flasks?

Andrew Werby
www.computersculpture.com


#3

Andrew,

Did you run the Perfactory parts through a flash-oven (which
blasts them with high-intensity light) before burning them out?
That's supposed to cure the resin that remains inside the parts
uncured through the build process, promote melt-out, reduce ash
formation, and speed up the burnout cycle. 17.5 hours seems like a
long time. Are these fairly big flasks? 

I don’t do my own printing, I have various service bureaus do that
for me (soon I hope this to change). The company I have printing my
models on the Perfactory machine do cure them in a flash oven and
this burnout cycle is their recommended cycle. They cast as well as
print so I trust their input. The flasks I am casting are ususlly 3 X
6 inch and contain a number of models on a central tree. I agree that
17-1/2 hours seems long but at their given temp hold times and the
ramping rate they advise, this is what it works out to and the
castings have been very successful; so I haven’t attempted to change
the schedule they 1st recomended.

If you have another burnout cycle which you use for the Perfactory
+/or Viper models please post it to the group, I’m always open to
better, quicker, more cost effective suggestions and I am very
willing to try new techniques. Personally, I like Solidscape models
for their easy burnout properties, but some modelsare better done in
resin printing to get the fine detail and the durability I frequently
need for my clients products.

Thanks for the comments! I hope you can provide an effective, faster
cycle!

Paul