object and to work with them when we were designing the experiments,” said Cary Forest, UW-Madison phys- ics professor. Casting the two sections in A356-2 aluminum, PCM built massive mul- tiple air set molds to cast the 11,500- lb. hemispheres. (T e sections each weighed 6,800 lbs. after machining.) At nearly 75,000 lbs., each mold in- cluded numerous risers and a complex system of chills. “T e casting required approximate-
ly 1,640 chills, which were all placed in the same locations to infl uence solidifi cation,” Griep said. “Special at- tention was paid to timing our shake- out procedure as we knew this would be critical in trying to duplicate both shrink and casting geometries.” In addition to a number of
pouring-related complexities, the hemispheres had to be machined heav- ily before delivery. T irty-two stain- less steel “water lines,” the concentric circles that ring the sphere’s interior, needed to be placed in exact locations to allow for proper temperature con- trol. PCM then tested the hemispheres for vacuum integrity, before an outside fi rm coated the interior in alumina to hold up to the high temperatures. T e completed dynamo was delivered to the university in January 2012.
Business in Learning T ese unique projects show what
metalcasting facilities are capable of producing for large-scale projects. But the contributions of Bay Cast and PCM to scientifi c research also highlight public research funding as a potential revenue stream. Both relationships between the metalcast- ers and universities are ongoing and orders continue to be placed. “T is relationship is more impor- tant than ever,” said Dan Griep, PCM director of tooling. “T ere are a lot of funds fl owing through the state of Wisconsin in these projects. If we can capture even half of the new UW business, it would have a huge impact on employment and enhance our ability to identify new business and understand where we should focus in the future.”
To cast each half of the dynamo, Portage Casting & Machining created a fi ve-section mold that weighed nearly 75,000 lbs.
PCM duplicated the molding and gating system from one pour to the next.
Engineers used approximately 1,640 chills to ensure both hemispheres solidifi ed uniformly. Sept/Oct 2013 | METAL CASTING DESIGN & PURCHASING | 35
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