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A question about investment casting...

Hokkmike
Can somebody explain in layman's terms the diffeence between cast and investment cast receivers. (on AR's)

Sako Fan
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3 comments

Date Votes
  • Tailgunner1954
    Cast: A form (normaly wood) is used to create a cavity in a sand mold, and metal is pored in. The form is removed before pouring takes place.
    Investment Cast: a form (normaly wax) is placed inside the sand mold and is melted by the metal being poured.
    The wax form is "near net" or finished size and can include any number of features (internal bores, rails etc) that a wood mold can't as it must be removable. Investment cast parts require less "post casting" work to finish.

    Whittemore
    Some guys like a mag full of lead, I still prefer one round to the head.
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  • hslaterpryce
    "Investment Casting" - A large $$ "investment" is made in a tool/die that has a cavity of the EXACT shape as the piece that you desire. If there is a requirement for passages or details internal to the part, a "core" (generally ceramic)is inserted in the die and held in the proper location in the die by an external piece or pins. Wax is then injected into this die, allowed to cool (freeze) and is removed. That wax is then dipped in a series of dips (proprietary ceramic mixtures/suspensions) and dried between each dip. The wax is then melted out and you are left with the mold into which you pour the metal of your choice. After the mold cools the mold (shell) is broken away and you have the casting. If a core was involved this it is then removed in a pressurized vat of hot caustic which leeches out the ceramic core. The part is then "finished", excess metal etc removed, and non-destructive testing (Xray-for internal defects and flourscent penetrant-for external defects), if required, is performed.

    Regular "casting" is done using a one time form, generally sand, that is formed into a mold using an insert that is used over and over again. Internals may also be formed in this process, again using a "ceramic" core that will generate the internal geometry. Metal is poured into this mold, the metal cools and the sand is removed. "Sand" castings generally have a much rougher finish and are almost always larger in size. The remainder of the process is very similar to investment casting.

    Hope this helps! If you need any further explaination you can E-Mail me at:

    hslaterpryce@pccair.com
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  • duppee
    I've always read that the investment process included a ceramic coating being used to cover the wax. The wax melts out when the ceramic is fire-hardened, and metal is poured into the hollow ceramic "mold". After the metal hardens, the ceramic is just broken off of the metal part.
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