12:00 p.m. - 1:00 p.m. LUNCH 1:00 p.m. - 1:40 p.m.
1:40 p.m. - 2:20 p.m. Paper No. 3
Cristobalite Formation in Investment Casting Shells George Salomon, Ronald Doles, Francois Batllo, Nalco, Booth 418 Cristobalite is a polymorph form of silica converted from quartz or fused silica and stable only at temperature above 1470C. Because of the energy intensive reconstructive nature of the transition from cristobalite to quartz or tridymite upon cooling, Cristobalite remains in a metastable form at low temperature in silica base investment casting shells. Furthermore as the temperature decreases, cristobalite undergoes a crystalline phase transition from its cubic form beta to a tetragonal form alpha around 220C. This phase transformation is accompanied by a volume contraction of about 5% creating strains, defects and cracks in the shell. While some casting applications benefit from weaker fired shells with easier shell removal or knock-out, others rely on the mechanical integrity of the fired shell for dimensional and throughput consistency. In this work, the factors impacting cristobalite formation in investment casting shells were investigated by determining the impact of material composition, chemical and physical properties as well as heat cycle on the crystalline structure and strength of the material.
Process Improvement in the Wax Room with Solucore®
Plus J23 Soluble Core Wax
Joseph Stanco, Randy Morss, Kenneth Zuis, REMET® Al Webb, Cera-Met, Booth 407 Soluble wax cores enables precision investment casting foundries to incorporate internal features that cannot otherwise be obtained through hard tooling inserts or ceramic cores. However, as foundries continue to meet challenges to cast ever larger investment castings with more complex internal features, soluble wax technology has not kept up. For example, increased volume of soluble wax required for some patterns leads to longer dissolution times which slows down productivity. End users have also seen increase in surface crazing or cracking in larger cores along with air entrapment. This has resulted in higher reject rates and increased production costs. Working closely with Cera-Met, REMET’s new Solucore®
implemented into production. This paper presents results of productivity analysis that evaluated the performance of Solucore®
Plus J23 soluble wax was evaluated and successfully Plus J23 in
injecting larger soluble wax cores with improved surface finish and faster dissolution rates while maintaining dimensional requirements of existing tooling. Improvements in processing soluble wax cores has also resulted in reducing the foot print in the wax room, lowered production costs and delivered higher quality castings to the customer.
Paper No. 4
October 2016 ❘ 21 ®
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