Conference mirrors industry optimism.

A record 1000 metalcasters and foundry products suppliers attended the third annual investment casting technical and operations conference, Oct 713 in Dallas.

Representing one of the fastest-growing segments of the metalcasting industry, the conference reflected industry optimism that new technologies and processes will ensure investment casting an increasing share of the market.

The industry should experience double digit growth for the next three years despite the current economic slowdown, according to R. Russell Stratton, executive director of the Investment Casting Institute. He reported that results of a recent ICI survey showed investment casting forecast increases of 19% in 1990 and 14% in both 1991 and 1992. NETCAST Awards

A highlight of the conference was the presentation of ICI's NETCAST awards. The awards recognize the quality and economies attainable through the use of investment casting for high-performance applications.

Placing first this year as the premier example of investment casting was a jet engine fan frame hub produced by Precision Castparts Corp, Portland, OR. Precision Castparts Corp also was honored for the aerospace category. Other NETCAST award winners were: Ceramet Div/Howmet Cercast (USA), Inc, Bethlehem, PA, nonferrous category; and Pine Tree Castings, Newport, NH, commercial category.

Keynote speaker for the conference was retired U.S. Marine Col. Robert Overmyer, a former astronaut and currently an executive with McDonnell Douglas Space Systems Div. Overmyer made two space flights as a shuttle pilot and as a mission commander during which metallurgical studies on crystal formation in zero gravity were conducted.

"The investment casting industry has made great advances in near net shape casting technology, but the need for a related economic partnership between users and producers has never been greater," Overmyer said. Technical Developments

Among the 35 technical presentations that drew special attention, one modem casting / December 1990 involved a revolutionary melting system, another covered shell drying involving the elimination of toxic agents and the third covered the direct delivery of low-temperature wax to injection cylinders.

Containerless, or levitation, melting was one of the technological highlights demonstrated at INCAST Roundup'90. The revolutionary process, developed by the electromagnetic processing laboratory at the Univ of Alabama, suspends a metal melt in an electromagnetic field. This frees the isolated molten mass from any nonmetallic inclusions or crucible contamination.

Known as Bama Therm, the development program was funded and jointly developed by the university and Inductotherm Corp. According to Dr. Thomas Piwonka, director of the Univ of Alabama Metal Casting Technology Center, the technique produces sound castings uncontaminated by impurities and gas porosity.

He said the process has proved effective for aluminum alloys and that work is under way to apply the technology to ferrous, titanium and superalloys.

Water-based colloidal silica for producing shells for investment casting is gradually replacing ethyl alcohol-based slurries because of the latter's toxicity, according to Spencer Goland, Cargocaire Engineering Corp.

Though colloidal silica takes longer to dry than the ethyl silicates because of its lower vapor point, environmental disposal problems with ethyl silicate binders have given the 35-year-old colloidal process new life.

One of the more difficult problems associated with the colloidal silica binders is controlling water evaporation from the dipped shells at a consistent and predictable rate.

Controlled water evaporation is the key to successful shell production. Drying done too slowly interferes with production efficiency and too rapid an evaporation rate can cause excessive shell failure.

The use of desiccant dehumidifying as a shell drying agent was described as a solution for drying rate control. The desiccant, lithium chloride or a silica gel, is impregnated into in a large, fluted, rotating honeycomb wheel through which humidified air is forced.

Since the dryer can be regenerated with natural gas or steam, the desiccant method of moisture removal is reportedly less costly than refrigerant drying systems.

The benefits of low-temperature injection of wax to the quality of investment casting patterns was discussed by Peter Witham, American Casting Equipment. He said the two reasons for injecting patterns and sprues at a low wax temperature were quality and productivity. Injecting wax at a temperature closer to its solidus point can greatly reduce the amount of sink and cavitation that occurs during the cooling process. This lessens the time wax is in the tool.

Using wax at lower temperatures also reduces its tendency to entrain air, but requires careful control of temperature loss as the material moves from the wax melter through the wax handling system to the injectors.