Slide 11 of 24
Notes:
Polyurethanes used from Innovative Polymer (get contact information)
- Hardness - Polyurethane Shore A and Shore D hardness
- Machinable with Fly-Cutter to Shore Hardness 90A
- Bond Issues - when selecting materials, materials with ~.003In/In shinkage. Cure times are broken into three times: Gel Time, Demold Time, Ultimate Cure.
- Gel Time - This is the working life of the material in its liquid state. After this time has expired, the polyurethane must be de-gased and in its mold.
- Demold Time - This is approximately the time after which the part can be removed from its mold (i. e. geometry is stable) and will probably be machinable. If material is soft or machining intricate wait 2x or 3x the demold time before the next process step.
- Ultimate Cure Time - After this time, the polyurethane has reached its final hardness (significantly harder than after the demold time).
