15th WCIC Agenda


mould loading into the furnace, mould pump down stage, mould raise to heating/pouring position, mould heating (DSSX process), liner and ingot loading, alloy melting, mould pouring, casted mould unloading and used liner removal. Among each of these operations, there are many subtasks that should be identified, analysed and optimised. Proper cycle process time analysis enables a view of the time consumption of each process stage, and the best synchronisation strategies to avoid wasted time and ensure the fastest cycle time is achieved. This work will show how furnace design principles can permit the operator to achieve the fastest, most productive, most efficient, and reliable casting process.


10:45 a.m. – 11:15 a.m. Investigation on Permeability Measurement Method of Investment Casting Shell Molds and Influencing Factors on Permeability Ryosuke Naito, IHI Corporation


Shell mold management is important to improve the stability of the investment casting process and their production. The permeability of shell molds is an important factor because it affects shell molds cracking while dewaxing, shell dry time, and smoother run of metal in shell molds. Permeability has been measured by various methods


in the investment casting industry. In the Ceramics Testing Guidebook by ICI, three permeability measurement methods are introduced. However, there are rooms for improvement for permeability measurement accuracy and stability. In the Japanese industrial standard (JIS), a permeability measurement method for ceramic materials is introduced. They are used for various ceramics such as bricks or concrete materials. There is a possibility to improve accuracy and stability of permeability measurement by the JIS method. However, this method is currently not applicable for investment casting shell molds. In this study, a sample preparation process and sample shape are checked to apply the JIS method for shell molds. Then, a relationship between shell conditions and permeability values is studied.


11:15 a.m. – 11:45 a.m. A Novel Prime Coat Slurry Mineral for Aluminum Investment Castings Steven Ashlock, Kyanite Mining Corp., Booth No. 324 Kevin Rudolph, O’Fallon Casting The selection of a face coat refractory material to be used


in investment casting is crucial when evaluating “as-cast” quality. The face coat material must be refractory, as it needs to be able to withstand the “super heat” of the molten metal to avoid defects caused by mold-metal reactions. Ideally, the material would be non-wetting so that the molten metal never has a chance to penetrate the porosity of the prime coat. The prime coat slurries must have adequate flow-behavior (rheology) to ensure the casting maintains the intricate detail of the pattern. Zircon is nearly always used in prime coat slurries


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and prime coat stuccos. This is primarily because zircon is a stable refractory mineral and can withstand the superheats used to cast stainless alloys. However, in applications where the alloy temperature is much lower than iron or nickel- base superalloys, high temperature refractoriness may not be needed; e.g. investment casting aluminum. In aluminum castings, the backup materials may differ from steel, but the prime coat material is often the same: zircon. Zircon is commonly used even though aluminum alloys melt at significantly lower temperatures than their steel counterparts. Molten aluminum is corrosive and readily reacts with most refractories through the reductive action of aluminum. This corrosiveness causes mold-metal reactions and leads to surface defects, increasing finishing labor. Zircon does a good job resisting this corrosion but comes at a significant cost and is over-kill for aluminum casting applications. Kyanite Mining Corporation has recently developed a new prime coat slurry mineral alternative that is both refractory enough to withstand the temperature of aluminum superheat and exhibits non- wetting characteristics with molten aluminum, leaving a smooth as-cast surface. This paper will discuss the viability of this new prime coat slurry for aluminum investment castings through laboratory testing and a foundry case study.


11:45 a.m. – 12:30 p.m. LUNCH - Disneyland South Ballroom


12:30 p.m. - 1:00 p.m. A Shop Floor Approach to Continuous Improvement in IC CF8M Components for Biomedical Applications Dr. Roger Lumley, AW Bell Pty Ltd., Booth No. 313 The current study formed part of a continuous improvement


program in which components made from Alloy CF8M used in biomedical devices were evaluated. The purpose of the study then was to isolate causes of scrap or rework and in particular, those that required remediation by defect removal and repair. Perceptions of the established production methods and poor understanding of acceptability criteria were found to be some of the major impediments to long term remediation of problems. A range of variables were examined that relied on accurate record keeping and measurement of key quality data by shop floor staff, as opposed to management or technical staff. It was shown that, among the variables assessed, over processing the investment casting shells prior to casting, de-slagging procedures during melting, entrained oxides, alloy composition, shell temperature, melt temperature, and manual handling during casting all had major influences on variability. Understanding these variables in detail meant that the amount of scrap, rework, welding and straightening of castings was able to be significantly reduced. Providing shop floor staff with the ability to actively contribute to R&D programs and hence manufacturing process development was found to be one of the greatest contributors to improving productivity of investment cast stainless steel in a production environment.


August 2022 ❘ 25


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