Lost PLA casting
FDM printing can create expendable patterns, but layer lines, hollow geometry, ash, expansion, and burnout need a plan.
Lost PLA replaces wax with a printed thermoplastic pattern. The print is invested, heated until the plastic leaves, and the cavity is cast. It can bypass silicone and wax injection for one-off geometry.
Design for disappearance
PLA does not drain like foundry wax. It softens, expands, decomposes, and may leave ash. Thick solid prints increase pressure on the shell. Hollow patterns, controlled walls, drain paths, suitable infill, and venting help—but the system must match a tested schedule.
Layer lines and support scars transfer into metal. Repair them before investment unless intentional. Sprues may be printed, wax-added, or combined.
Use it where it earns its keep
Lost PLA suits unique parts, internal geometry, rapid iteration, and patterns too costly to mold conventionally. It is less attractive when a reusable mold would support an edition efficiently.
Burning plastics creates hazardous emissions. Kiln ventilation, investment compatibility, and foundry-approved procedures are mandatory.