Meaning
Post-molding subtractive operations remove excess material or add fine details to a molded plastic component after it has been ejected from the injection tool. Performing secondary machining allows molders to achieve dimensional tolerances, internal threads, or complex geometries that are impossible or too expensive to produce directly through the molding cycle.
Feature Addition
High-precision components often require threaded holes or deep undercut regions that would require complex collapsible cores in the primary molding tool. By performing subsequent drilling, tapping, or milling, the molder can simplify the tooling design and reduce the risk of mechanical failures in the mold. This operation runs on standard CNC equipment or dedicated automation cells.
Tool Wear
Cutting composite polymers with abrasive glass or carbon fiber reinforcements accelerates the degradation of milling bits. Tool steel wears quickly, causing burrs. Molders use diamond-coated cutters to maintain tolerances.
Economic Tradeoff
Adding a post-molding operation increases the total cycle time and labor costs associated with the part. For thin-walled enclosures, the cost of machining a feature can exceed the cost of the entire injection molding process. Molders must analyze the trade-off between the high initial cost of a complex mold and the ongoing operational cost of subsequent mechanical processing.
