Permanent Mold Castings
Molten metal is gravity poured into cast iron molds, or graphite molds coated with a ceramic mold wash. Cores can be metal, sand, sand shell, or other. Molds open and castings are ejected. The Low Pressure Permanent Mold method pressure-pours up to 15 p.s.i.
Metals: Aluminum, Zinc, some Brass, Bronze, H.C. Copper, Lead and Gray Iron.
Size Range: Limitation mainly foundry capabilities. Aluminum and Copper base: ounces to 100 lbs. Ferrous: 60 lbs. max.
Tolerances: Aluminum: Basic ± .015" Add ± .002"/in. If across parting line add ± .010" to ± .030" depending on size Copper Base: Similar to Investment Iron: ± .03" Basic.
Surface Finish: Aluminum: 150-250RMS Copper Base: 125-200RMS Ferrous: 200-350RMS
Minimum Draft Requirements: Non-Ferrous: Outside: 2° Min (3° desirable) Inside: 2° Min (4° desirable) Ferrous: Outside: 1° Inside: 5°
Normal Minimum Section Thickness: Aluminum: .100" for small areas, up to 3/16" or more for large areas. Copper Base: .060" Ferrous: 3/16" for small areas, 1/4" normal.
Ordering Quantities: Minimum one day's run: (100-1,000 depending on size).
Normal Lead Time: Samples: 8-20 weeks.
Production: 4-8 weeks A.S.A.
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