Best results are obtained in 6 inches or less in either ferrous or non-ferrous alloys. Casting lengths of up to 14 inches, as well as weights of 10 pounds in aluminum and 25 pounds of steel, are now available.
Certain design factors are essential for the production of successful investment castings.
a. Fillets should be incorporated whenever possible, because the production of a sharp angle weakens the casting. A minimum radius of 1/32” should be employed, with an average radius of about 1/16”.
a. Blind holes can be cast if they are no greater in depth than they are in diameter. The minimum diameter is ¼” for blind holes.
b. Hole size – Holes as small as 1/8” diameter may be cast. The depth of the hole can be as much as four times the diameter. Ceramic cores allow for almost any hole dimension.
a. These are generally impractical
4. Wall Thickness
a. A minimum wall thickness that is practical for investment casting ranges from .100 to .125.