design details D
Designers Steer Capabilities in Consolidation JITEN SHAH, PRODUCT DEVELOPMENT & ANALYSIS, NAPERVILLE, ILLINOIS
CASTING PROFILE
Cast Component: Auxiliary drive casting.
Casting Process: Vertically- parted green sand. Material: Gray iron. Weight: 170 lbs. Dimensions: 32 x 18 x 10 in.
Casting Application: John Deere tractors.
Casting-in features is often economical, but sometimes drilling them in later is more cost-effi cient, so the designer should consider both options. • Depending on the feature size (diameter and depth) and section wall thickness in the vicinity of a hole, the design engineer must make a call to design it as-cast or cast solid and then drilled.
• In highly automated molding processes, cores should be minimized for increased cycle times, better dimensional accuracy and a clean casting.
• For the auxiliary drive casting, engineers made as-cast vs. drilled hole decisions on the following sections: - Deep, cored pockets needed higher draft angles. - Mounting holes on the vertical surface are cast-solid and drilled later.
- Mounting lugs are cast solid.
across multiple tractor options. T e design reduced part numbers, eliminated infl ated inventory levels and suc-
C
cessfully met limited space and weight restrictions. T e supplier produced the part via vertically-parted green sand molding, which is a cost eff ective molding process with tight dimensional accuracy and reproducibility and good as-cast surface fi n- ish. It’s a fl askless molding process, meaning molds are created without a metal or wood frame, which improves cycle times.
reative casting design with a sound understanding of the casting process and its limitations allowed engineers at ThyssenKrupp Waupaca, Waupaca, Wis., and John Deere to work together to consolidate multiple castings and weldments into one auxiliary drive casting for a tractor engine. The casting is a common part
18 | METAL CASTING DESIGN & PURCHASING | Sept/Oct 2011
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