prototype castings with the printed molds and/or cores. One such part was a transmission
housing for one of John Deere’s iT4 tractors. Te part was originally slated to be produced via the traditional route. But an aggressive launch plan drove the team to utilize additive man-
ufacturing. John Deere has found that conventional CNC-cut tooling for prototypes can take between four and eight weeks, depending on part size and complexity. More coreboxes means more time and more cost. With the conventional approach, the transmis- sion housing would have required nine
coreboxes and assembly. Using additive manufacturing, John Deere Technol- ogy Integration Personnel determined only six cores were needed, four of which were assemblies. Te conven- tional prototype approach would have required a 20.5-week lead time for tooling, castings and machining. Using additive manufacturing cut the total lead time to just 15 weeks and saved close to $44,000 in total spend. “Reducing the number of cores led to cost savings and time sav- ings, which permitted us to prevent delaying a tractor build,” Dickey said. “Tat was the key driver, that we would not delay a build. And we would have had to with a convention- al prototype tooling approach.” John Deere’s foundry in Waterloo,
Iowa, does not yet have its own 3D printer, so it works with third-party facilitators to produce its molds and cores and ship them to Waterloo. Ac- cording to Dickey, the company has used additive manufacturing on close to a dozen projects a year since 2011 and is considering investing in its own 3-D printing equipment in the future. “I see our use growing,” Dickey
said. “You can use it in casting design for cost reduction in testing. Instead of changing the tooling or making a new corebox, you can make a new proto- type core. We have completed projects at John Deere Foundry for large trac- tor castings and for our sister factories and global operations for entire mold packages, as well.”
Is It a Right Fit?
Te possibilities of design using 3D sand printing seems limitless in shape, if not in size, but the cost will be high enough in many cases to be a deterrent. Right now, the equipment needed to print the molds and cores is a considerable investment and the resin and sand used to build the molds are not inexpensive. Domestic sources are scarce, and the sand has to be specially processed to achieve a unique screen distribution. So, the decision to use a printed sand mold or core is not made lightly. Murray has seen his customers
arrive at additive manufacturing for a number of reasons and at different
38 | METAL CASTING DESIGN & PURCHASING | Nov/Dec 2013
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