The improvement of dimensional accuracy on the part allowed the 10% reduction in scrap at the assembly line because the alignment of the alternator and compressor pulleys to the engine flywheel pulley were dictated by Deere to be no greater than one half of a de- gree from parallel.
Cast to Impress The AFS/Metal Cast-
The casting process (right) allowed the design team to use bends and curves where the weldment (left) was straight, thereby optimizing the space utilization of the bracket.
In addition to the redesign, one final
factor helped sell Deere on the cast bracket component. With the help of a third party supplier, the design team was able to procure a full scale ste- reolithography rapid prototype, which the company mounted on an actual engine with working alternator and air conditioning compressor. “We cut some of the lead time out
by taking that model to the machine shop so it could make fixtures,” Von- nahme said. In fact, a total of only four months
passed from the time Deere began planning the casting conversion to its approval of a sample submission.
Deere Prudence In the process of designing a more
castable part, the design team of Deere, Dotson and G&V also developed a part that was more conducive to the end- user’s needs. The team added a round extrusion on the tip of the part where Deere bolts the skid loader’s dipstick. Previously, a clamp was added in post-processing. The team also positioned mate-
rial on the component only where it was needed. According to Witt, by implementing curves and bends where the weldment was constrained by its straight and flat stock steel pieces, the bracket more perfectly
May/June 2010
fit the envelope of the Deere skid loader’s engine and weighed less than its welded predecessor. “[The part] sits underneath the cab,
where space is limited, and there is little room between the bracket and engine profile,” Witt said. “The space between the cast bracket and the alternator and compressor also was reduced to allow for the electronic engine throttle management system.”
ing Design & Purchasing Casting Competition is judged by four indus- try experts on several criteria. One is the po- tential for marketing the metalcasting process to potential end-users. So, conversions to the cast- ing process from another manufacturing method
have an advantage. But that’s not what tipped the scales for Dotson’s alterna- tor/air conditioning bracket. “When I noticed that when the
bracket was mounted, the com- plex geometry was designed to fit better than the weldment—an ab- solute match to the final part rath- er than an appendage—that did it for me,” said one of the casting contest judges.
METAL
Because the 11-piece weldment required multiple processing steps, the part often arrived at John Deere’s assembly line out of specification.
Metal Casting Design anD PurChasing 27
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