Mold Materials

Advantage

Disadvantage

Urethane

Relatively inexpensive. If tolerances allow a mold can be made from an existing part or for greater accuracy an oversize pattern can be made.

Not for tightly toleranced parts. Variability of 0.002� to 0.003� per linear inch of part. Limited lifespan. Molds can last for several hundred cycles but will need to be replaced periodically.

Reinforced Urethane

Relatively inexpensive. Dimensional stability is better than pure urethane but still not as accurate as a metallic mold.

Not for tightly toleranced parts. Variability of 0.001" to 0.002" per linear inch of part. Limited lifespan as above

Silicone

Can capture great detail and due to softness can stretch and evacuate unusual shapes

Somewhat more expensive than urethane.

Aluminum

Relatively low cost. Fast heat transfer leads to shorter cycle times and lower part costs. Relatively long tool life

Not extremely durable, but can last a very long time.

Tool Steel

Very long tool life. Durable and dependable.

Most expensive material for mold manufacture.