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Program highlights products, processes.

New product and process developments were the focus of the papers presented in the investment casting sessions during this year's Casting Congress.

On the process side, an innovative melting and casting process for titanium and reactive alloys was described by D.S. Reed and M.L. Jones, The Duriron Co. (91-162). Patented in 1988, the process is called induction skull melting. According to the authors, the process uses a segmented, unlined, water-cooled crucible surrounded by an induction coil for melting. The crucible is placed in either a vacuum chamber or used with an inert gas shield for melting and casting. They reported that the system requires no insulating slag, as with similar systems, and is capable of melting up to 50 lb of titanium per heat.

Among the advantages of the system, according to Reed and Jones, are "alloy homogenization and flexibility, coupled with a nonceramic crucible, lends itself extremely well to the production of rather exotic alloys such as titanium aluminides, nitinol shape memory alloys and various other reactive metals. Due to the lack of refractory present in induction skull melting, a great deal of interest exists in the superalloy community."

Four authors from Cober Electronics, Inc. and the Investment Casting Institute reported on a study designed to measure the dielectric properties (microwave properties) of the common ceramic materials used in investment casting molds 91-166). Microwave is considered an alternative to conventional dewaxing methods because the wax is removed at lower temperatures, allowing it to be reclaimed with higher yields. According to the researchers, "There is also a significant energy savings on a Btu basis with the microwave process." Their work showed

at most materials that are used in the shell will heat very little or not at all when placed in a microwave cavity. The result is that an investment casting mold can usually be efficiently and uniformly heated using microwave techniques.

Two product developments were also described during investment casting sessions. S.G. Oswald, VSX Corp., reported on his foundry's conversion to preformed ceramic pour cups to alleviate cup splitting and breakage of their existing dipped pour cups (91-144). Oswald demonstrated how the foundry will save $100,000 annually by using ceramic cups, reducing both scrap and labor costs.

Oswald, together with M.A. Lucatorto, NALCO Chemical Co., reported on another effort by VSX to reduce costs by using a polymer-enhanced colloidal silica binder (91-161). This development, according to the authors, resulted in a savings of more than $98,000 because of a 24.3% decrease in scrap.
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Title Annotation:95th AFS Casting Congress, May 509, 1991 - Birmingham, Alabama; A Technical Review: Investment Casting Division
Publication:Modern Casting
Date:Jun 1, 1991
Previous Article:New technologies address industry needs.
Next Article:Close attention paid to gas testing, MMCs.

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