Low internal tool pressures (<50psig) developed during injection of METTON LMR, allows numerous low-cost tooling options (relative to sheet molding compound {SMC} and injection molding tools). Available mold types range from prototype to high volume production. The table below shows durability, surface quality, cost (as a percentage of injection molding tooling) and some general information for each tool construction.
| Tooling Construction |
Projected Tool Life (# of Parts) |
Surface Quality |
Est. Cost vs. Inj. Molding Tooling, % |
Comments |
PROTOTYPING |
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| Epoxy/Polyester | <100 | Fair | 15 | Most common prototype. Durability for short-term production cannot be predicted. |
PRODUCTION |
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| Nickel Shell | 150,000 | Very Good | 40 | Changes to the cavity side cannot be readily made. |
| Cast Aluminum | >50,000 | Good | 20 | Excellent heat transfer. Light weight. Non-Class A parts only due to porosity. |
| Cast Kirksite | >50,000 | Good | 35 | Excellent heat transfer. Non-Class A parts only, due to porosity. |
| Machined Alum. | >150,000 | Excellent | 30-60 | Excellent heat transfer. Tighter dimensional tolerances vs casting. |
| Machined Steel | >150,000 | Excellent | 80 | Highest surface quality, cost, longest delivery time, weight disadvantage. |
