Simple Invention Speeds Up Metal Investment Casting Process

New process cuts time by at least 33%

Shells being heated to pour metal

Shells after removing wax

pattern in autoclave

• Faster cycle time for dipping shell• Can build a shell with 6 layers plus a seal coat in an 8 hour shift using 1 hour cycle time• Need lots of air flowing over the shell between coats• Appears to be easier to immerse tree into fluidized bed with

AMS additive• It is possible to reduce cycle time to 30-45 min

• Characteristics of the shell after 1 hour when it is ready for redipping

• Surface of the shell is hard• Shell still contains moisture• We say the shell is dippable: we do not say the shell is dry• Shell materials does not peel off in the slurry when the shell is redipped

• Time line to build shell, remove pattern and pour metal – 1 hour cycle time• Day 1

• Build shell in one shift• Dry shell overnight

• Day 2• Remove pattern• Heat shell and pour metal

Shells after metal has been poured

Metal part – before and after final finishing processes

Dan McGuire1 and Eric Hellstrom2

1University of Wisconsin-Whitewater, 2University of Wisconsin-Madison and Florida State University; Patent # 7,278,465, Support from WiSys

Clinton L. Atwood http://www.wtec.org/loyola/rp/10_01.htm

Wax patterns with and without 1st coat

Applying stucco in fluidized bed

Summary• We have developed a new, simple, inexpensive

process that drastically decreases the time needed to build a shell for investment casting.

• The heart of the invention is an amorphous mineral silicate that is added to the stucco.

• No change in other materials and the fabrication methods

• Time reduced by at least 33%• Cost reduced by at least 25%

• Same basic process currently used for metal investment casting. • Useable with fluidized bed and rainfall method for wax, Styrofoam, and all burnable patterns

• Major modification is to the stucco:We add amorphous mineral silicate (AMS) plus an organic (e.g., corn starch) to the stucco. • No changes in slurry• AMS and corn starch are mixed

with stucco• Can be used with all standard

stuccos - zircon, silica, alumino-silicate, alumina

• Can use additives in all stucco coats• Some companies choose not

to use it in the face coat- primary stucco because the first layers dry so quickly

• No changes when applying stucco with fluidized bed

• Add one step before redippingwith rainfall method to remove

loose stucco

• Time line to build shell, remove pattern, and pour metal – 45 min cycle time • Day 1= 12 hour shift

• Build shell• Remove pattern• Heat shell and pour metal

• Other factors• Shell is lighter so it takes less heat to bring shell to pour temperature• Does not use any drying accelerants, like alcohol• Green, environmentally friendly, non-toxic• Potential to recycle shell• Shell breathes• Shell has larger Modulus of Rupture (MOR) than traditional shell• Compatible with all standard metals

• Light alloys – aluminum, brass, bronze• Cast iron• Stainless steels

• Modified shell breaks off casting more easily and in larger pieces than traditional shell

• Cost should be about 25% less expensive than traditional shell

For licensing contact:

Paul PucciWARF608-262-4924 ppucci@warf.org

For more information on the process see:

www.FoundrySolutions.net