What have you guys seen for good bits to CNC machine compound shapes (molds) from pure fiberglass? I assume carbide at a minimum but do shops have to use diamond bits to get decent life and/or not heat up the laminate by cutting too slow/dull? Styles (in either carbide or diamond coated)?
BTW this is a bit different than just trimming fiberglass- this is 3d machining solid laminate.
I have had decent bit life 3D machining carbon plate with coated (TiCN) 3-flute carbide ball-end mills. The three flute with a single center cutting flute gives better clearing of dust and seems to leave a better surface finish. Diamond coated (PCD-$$) is the best though!
The hardness of the laminate makes a big difference. With epoxy wet or infused, it is nice to post-cure to bring the hardness up. Well compacted/autoclaved prepreg is the nicest to machine.
Harvey Tool makes some nice composite-specific tooling with more flutes - both PCD and carbide.