polypropylene (SLS)

Polypropylene printed by selective laser sintering is a semi-crystalline thermoplastic built from fine powder that a laser fuses layer by layer in a heated bed. Loose powder supports the part, so no support structures are needed and nested geometries are possible. Surfaces are matte and slightly grainy with some residual porosity, and shrinkage and warpage on cooling require tight bed temperature control and dimensional allowances. Strength is somewhat anisotropic, with layer bonding usually the weaker direction, and parts are cleaned of powder by blasting. Typical uses are functional prototypes, housings, ducts and fluid-handling parts needing chemical resistance.