The_Great_Orgo
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Lost PLA Sand Casting
A friend of mine does lost PLA casting and he said that in order to remove the PLA from the mold, they had to heat it to 500 degrees. Why is this? The
melting point of PLA is only 160 or so. Is this due to the sand mold being an insulator/ a poor conductor of heat?
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Gearhead_Shem_Tov
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Quote: Originally posted by The_Great_Orgo  | | A friend of mine does lost PLA casting and he said that in order to remove the PLA from the mold, they had to heat it to 500 degrees. Why is this? The
melting point of PLA is only 160 or so. Is this due to the sand mold being an insulator/ a poor conductor of heat? |
Lost wax casting uses plaster and fireclay moulds which don't have the porosity of clay-bonded green sand moulds (which is what you seem to be
thinking of). With lost wax you first place the inverted mould with its wax model in an oven to melt the wax out. It then needs to go in a higher
temperature kiln to burn all the remaining wax out so that even soot no longer remains. Lost PLA casting would be similar except it would require
higher temperatures for both phases.
You have to burn the modelling material completely out of the mould because otherwise the gasses generated when molten bronze or even aluminium make
contact would instantly vaporise the remaining film of volatile material (wax, styrofoam, PLA, etc.). Best case this would spoil the surface finish
with bubbles and voids; worst case it would cause an explosion during the pour.
[Edited on 27-11-2018 by Gearhead_Shem_Tov]
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The_Great_Orgo
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Thank you, that exactly answers my question.
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