Metal or Plastic? Framing the Decision
Start with the loads and environment
Die castings carry structural loads, dissipate heat and shield EMI; injection molding wins on weight, corrosion immunity and integration of features like living hinges and snap fits. If the part houses electronics that run hot or must act as structure, metal usually leads.
Hybrid strategies exist: plastic covers over a die cast chassis.
Tooling and volume economics
Both processes need expensive molds, but die casting dies endure thermal cycling from molten alloy and generally cost more with shorter die life. Injection molding pays back at very high volumes with fast cycles; die casting competes on performance per part rather than pure cycle time.
Run a cost crossover at your forecast volume — not a per-quote snapshot.
Secondary operations differ too
Die castings often need machining, leak testing and finishing; moldings often need painting, ultrasonic welding or insert over-molding. Compare the finished-part cost, including every secondary step.
FAQ
Which process is cheaper per part?
Depends on volume and part function; plastics often win at very high volumes, while die casting wins where performance justifies material and tooling.
Can injection molding replace a die cast part?
Sometimes — requires redesign for plastic behavior (ribs, bosses, tolerances); a full revalidation, not a material swap.
Which has tighter tolerances?
Both are precise; die casting holds excellent net-shape tolerances on metal, molding holds fine detail — compare on your specific features.
Which is better for heat dissipation?
Die cast aluminum — its thermal conductivity makes it the default for heat-generating electronics housings.
All figures above refer to standard product data sheets; final confirmation is subject to written quotation.