Thermoforming vs. Injection Molding

Injection molding is used to make a wide range of parts but is often not the most cost effective process, especially for lower volume parts.

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Shapes produced Single surface Ideal for flatter parts Full 3-D Nearly any shape possible
Mold Type One part Only one side contacts the part 2 halves Part enclosed on all sides
Mold Material Aluminum Easy to machine Tool Steel Hardened after machining.
Mold Cost Low Only one part to mold and has to handle atmospheric pressure 14.5 psi. Generally $1,000 to $5,000 High 2 halves to mold and has to withstand several tons/sq.inch of pressure. Typically $30,000 to $100,000.
Mold Maintenance Minimal Wipe down to clean. No significant wear, typically lasts for 1 million + cycles. High Narrow ducts and corners eroded by hot plastic high pressure flow. Can require rework every 100,000 cycles.
Part Quantity Suitability Low to Medium 10 to 10’s of thousands Medium to High 10’s of thousands to millions
Part Trimming Medium CNC machine or die cut to remove sheet edges and add holes & other features Low With high cost molds minimal excess plastic to remove. Holes etc. can be molded in.