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Investment Castings in Ferrous and Non Ferrous Materials
Lost Wax Precision Casting Process
 Ferrous Investment Castings are castings that utilize Stainless Steel, including 300/400 Series Alloys and any Precipitation Hardened Steel Alloys. Non-Ferrous Investment Castings utilizes copper based alloys, zinc based alloys, aluminum, bronze and iron.
Investment Casting. Often called lost wax casting, is regarded as a precision casting process to fabricate near-net shaped metal parts poured from almost any alloy including: stainless steel, aluminum, brass, bronze and copper.
Casting by the investment process allows for parts to meet x-ray and non destructive testing specifications for: military, aerospace, semi conductor industry, valves, pumps and many other industrial applications.
The investment casting process consistently provides high integrity (sound) and dimensionally accurate castings. Cast part dimensions vary less than +-.001 from part to part.
Investment casting uses a mold that has been produced by surrounding an expendable pattern with a refractory slurry that sets at room temperature. The pattern (usually of wax or plastic) is then melted or burned out, leaving the mold cavity. Investment casting is also known as the “lost wax process” and as “precision casting”.
For more details, see the process chart for further explanation of Investment Casting.
PROCESS BENEFITS OF INVESTMENT CASTINGS (Lost wax)
- The process is capable of making parts from prototypes to high volume. Investment Casting tooling
is capable of making over 1 million parts per tool.
- Cast tolerance to +/- .005 or better, per inch
- Cast surface finish of 125 RMS or better
- Excellent cast details with regards to cast letter i.e. logo, names, part number, etc
- Reduced machining due to castings designed to near net shape
- Investment castings can have undercuts, blind holes, thru holes .250 or greater and, almost any
geometric shape or size
All of the above advantages reduce your casting costs.
MACHINING: Aluminum, brass & bronze, along with other non-ferrous and ferrous alloys, machine easily with today’s CNC & digital N.C. machining centers. Starting with a near net shape casting, machining times are reduced which, in turn, save $$
Castings can be quoted complete to print specifications by utilizing our in-house machining capabilities.
CASTING SIZES: Although some foundries can cast parts the size of a bathtub, most casting facilities pour parts in the 12” x 12” x 6” range with weights up to 50 pounds.
Please submit your design via email in STL, STEP, IGS, DXF, or PDF format to: dick@castingreps.com for an engineering discussion on your casting requirements.
TOLERANCES: Generally, +/- .005 per inch
Premium tolerances of +/- .003 per inch.
WALL THICKNESS: Investment casting can have a minimum wall thickness as thin as .030. Normal casting wall thicknesses of .080 to .125 are preferred for casting reliability.
DRAFT: There is NO DRAFT required in the lost wax investment casting process.
Please contact Dick Palmer to learn more about how we can work together to help to reduce your company’s costs using either the investment casting (lost wax) process or other casting processes. Mr. Palmer may be reached, toll free, at 888.494.0414 or via email at dick@castingreps.com
WAX INJECTION
The process begins with production of a heat disposable pattern. This pattern is usually made by injecting molten wax or plastic into a metal die or mold.
PATTERN ASSEMBLY
The wax patterns are attached by the gate to a central wax runner system. The runner system is called a sprue. Patterns, runners, and pouring cup compromise the cluster or tree.
SHELL BUILDING
The shell building technique involves dipping the assembly into a ceramic slurry and then into a bed of extremely fine sand. After drying, the process is repeated. Up to 7 layers may be applied in this manner.
DEWAX OPERATION
The completed shell is placed in a steam autoclave where the wax pattern melts and runs out through the gates and pouring cup.
FIRING THE SHELL MOLD: Preheat
Molds are placed into a kiln at 2000 degrees, this cures and hardens the mold.
CASTING
Molds are removed from the kiln while the mold is still hot to reduce thermo shock, metal is then poured directly into sprue cup.
SHELL REMOVAL: Knockout
Once molds have cooled for approximately one hour the ceramic shell is knocked off from the metal castings and runner system.
CASTING REMOVAL: Cut Off
Castings are cut from the sprue tree.
LOST WAX, INVESTMENT CASTING PROCESS
Mr. Palmer may be reached by calling toll free:
888.494.0414 or email: (dick@castingreps.com)
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