68th Annual Technical Conference & Exposition TUESDAY, continued
10:20 a.m. - 11:00 a.m.
Paper No. 12: Implementing Best Practices & Reducing Process Costs For Refractory Use in Investment Casting & Alloy Production Foundries
Phil Geers, Blasch Precision Ceramics, Booth 316 ICI member foundries, which include Investment Casting and Alloy production companies, are constantly working to preserve and improve the quality of their product. While they do this, they are challenged with tight deadlines, all while working with the available resources on hand. Because of these demands, best practices for refractory linings can be overlooked and in the worst case ignored by the foundry manager or plant engineer. The truth is the time required to implement best practices for foundry refractories is small, but it does require that standards and procedures are followed. Any time required for these best practices are easily recouped by achieving longer refractory life, more consistent heats, reductions down time and a safer foundry environment. In this paper, we will review best practices for foundry refractories (from simple to complex) that can be utilized immediately to improve refractory life and reduce cost.
AGENDA
11:00 a.m. - 11:40 a.m. Paper No. 13: The Effect of Firing Temperature & Time on Silica Based Investment Shells Strength Mingzhi Xu, Georgia Southern University Silica based shells are commonly used in the investment casting industry for its superior dimensional stability, thermal shock resistance and ease of removal. Investment shells are generally fired and/or preheated prior to the casting process to remove pattern residue and increase shell strength by sintering. However, it has been found in previous research that, if the firing time is not closely monitored, extended firing/preheating can weaken the room temperature shell strength, due to the coarsening of the ceramic grains.
In addition,
the reduction of surface area of fused silica impairs the amorphous to cristobalite phase transformation during the casting process, which causes difficulty on shell removal. In this study, the effect of firing time at different firing temperatures on the shell hot strength at elevated temperatures were systematically studied. Recommendations on maximum firing time were discussed.
11:40 a.m. - 12:20 p.m. Paper No. 14: Rapid, Low Cost Tooling for Small Engine Castings Dan Sokol, Renaissance Services – PERFECT – 3D, Booth 318 A historical challenge for the U.S. Air Force is rapid development and deployment of new systems to meet evolving and emerging threats. In recent years, a critical element in the new systems equation has focused on expendable and attritable aircraft. Investment castings are critical to the cost and performance of the small and medium-sized engines for these systems. Essential turbine engine components, produced from castings, impact cost, lead time, and performance. A key driver for these castings is the tooling used to produce them.
A growing need exists for engine component parts that can be delivered rapidly, affordably, and in both small and variable quantities. This presents a challenge for not only essential castings, but for the tooling required to produce them, as considerations such as tooling durability and life, non-recurring and recurring costs, design and delivery lead times all become important variables in the decision process. For example, conventional wax die injection tooling is proven to be durable for thousands of applications, but the lead time and non- recurring cost are prohibitive for a program that needs 250 or fewer castings to be delivered in a few months.
To address this need, Renaissance Services is leading a U.S. Air Force-sponsored program for Low Cost Tooling for Castings; specific focus is on castings for small turbine engines. The team consists of foundries (Bimac, HTCI, Nucor, and PCC) and small engine programs/ OEMs (Air Force Research Lab Responsive Open Source Engine, FTT, UAV Turbines). Included are castings for rotating and non- rotating components (rotors, impellers, stators) as well as structural components (casings, housings). Materials range from nickel-based alloys to steel and aluminum.
12:20 p.m. - 1:00 p.m. LUNCH 18 ❘ August 2021 ®
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