59th Technical Conference & Expo Program
ticularly during the injection of a wax, the changes in tem- perature profile during the injection process can have ef- fects on the flow and dimensional characteristics of a wax. An understanding of these mechanisms allows strategies to be developed that lead to improved process control and surface definition of wax patterns. Controlled stress rheometry and dynamic mechanical analysis (DMA) have been employed to study the behavior of waxes at the on- set of congealing under flow conditions in an attempt to measure these effects. Characterization of the wax using controlled-stress rheometry reveals phase changes that occur along with linear viscoelastic behavior. Temperature modulated DMA allows for the investigation of reversible and non-reversible phenomena in the melting and crys- tallization region of waxes. Temperature modulated DMA also provides high sensitivity for small and slow changes in crystallinity, e.g. during re-crystallization. The combina- tion of controlled stress rheometry and DMA yields new information about local processes at the surface of poly- mer crystallites.
11:25 a.m. - 12 noon. .................................. Paper No. 15 Nathan Robertson, Consarc Corporation Developments in Vacuum Furnace Design for Investment Casting Modern vacuum furnaces for investment casting come
in a variety of designs, shapes and sizes depending on application. This paper provides a review of modern vac- uum furnace configurations, the options open to foundries when selection the appropriate furnaces and discusses the advantages and applicability of each. Further, there are a number of developments in furnace technology in recent years which include a number of design features to: (1) aid process control, (2) provide excellent repeat- ability of casting, (3) provide highest possible quality of casting, and (4) achieve highest productivity rates. This paper will describe some of these features and develop- ments included in the latest generation of vacuum furnac- es, detailing the significant and distinct process advan- tages that they can offer.
12 noon - 1 p.m.
..................................................LUNCH
1 p.m. - 1:35 p.m. ....................................... Paper No. 16 Norm Hirtner, Avalon Precision Castings Mike Hascher, Eagle Engineered Solutions Inc. Melting Crucible Quality & Cost Improvements- ‘Low Hanging Fruit’ Foundry and quality engineers in modern investment casting facilities face a myriad of challenges each day in their quest to improve casting yields and quality, and lower total operating costs. Those challenges rarely fo- cus on products that “work” and typically focus on what “doesn’t work.” This paper examines the cost saving and
September 2012
quality improvement opportunities associated with the use of Sol- Gel bonded melting crucibles when compared to clay bonded melting crucibles. A detailed evaluation and comparison of these two types of preformed/prefired cru- cibles was conducted at Avalon Precision Castings with patented Sol- Gel bonded crucibles manufactured by Mag- neco/Metrel. The evaluation led to an increase in crucible life across a variety of ferrous, nickel and nonferrous al- loys resulting in a cost savings of 22% when compared a more traditional clay bonded crucible. The evaluation plan and results will be presented along with results of a “veri- fication” study conducted after the initial conversion from clay bonded crucibles to sol- gel bonded crucibles.
1:35 - 2:10 p.m. .......................................... Paper No. 17 Dr. Carlos Suchicital, Virginia Tech Investment Casting at Virginia Tech The new Kroehling Advanced Materials Foundry, home
to the Virginia Tech Foundry Institute for Research and Ed- ucation (VT-FIRE), officially opened in January 2011. The foundry has induction and resistance melting plus bonded sand, printed and investment molding. Patterns for invest- ment casting are currently being made by pouring wax into silicone rubber molds or by 3D printing. Engineering students are designing complex components (structural and non-structural) and rapidly turning their designs into metal components by investment casting. The polymers used for 3D printing pose many challenges when used as investment casting patterns. During burn-out, printed polymers generate greater amounts of gas, compared to wax, and the complete removal of carbon created by the polymer decomposition requires higher burn-out tempera- tures and longer times. This paper describes our efforts at developing a standard practice for the use of 3D printed polymer patterns for investment casting.
2:10 p.m. - 2:45 p.m. .................................. Paper No. 18 Sam Scott, ESI Group North America Dimensional Prediction – Trials & Research This presentation will look at the cost of scrap and
review the many distortion sources during the investment casting process. It will review previous simulation prac- tices and will explore efforts running casting simulation to get “as-cast” distorted shape, then running casting simu- lation on new cavity, which should end up deforming to the initial intended shape, then performing chained simulation to “back” thru the entire process.
3 - 6 p.m. ................................................................EXPO 6:30 - 8 p.m.
................................................RECEPTION
13
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32
