CAD rendering of a torpedo level (simplified). Aztalan used DFM concurrent costing to compare processes and determine the most cost-effective way to manufacture this part.
Aztalan Engineering uses DFMA to quote costs, analyze designs, implement process controls and communicate with customers and the supply chain
Taking Cost Drivers Out Of A Complex Part
Recently, Aztalan prepared a quote for a carpenter’s level (see Figure 1). This particular part was to be produced at a very large volume—hundreds of thousands—so costing it accurately was imperative.
The initial proposal called for machining the level out of a rectangular tube of extruded aluminum. The amount of scrap material was considerable.
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“The aluminum before machining weighed 1 pound. Afterward, the level weighed four-tenths of a pound,” Jim Hale, general manager at AEI.
He entered the machining information—because of the high volume of production, the part would have dedicated machines.
The machining operations would include high-precision milling of the leveling faces, milling the datums, and precision hole drilling and boring. Hale then printed out an initial costing report for use as a benchmark.
“I knew that the part would come in high,” he says. “The main cost driver was not the material—aluminum isn’t that expensive—but the time spent machining each feature.”
Hale used his baseline analysis as a starting point for seeing what processes would reduce machining time by creating a near-net part. “The typical starting point for a machined part is a standard size bar, plate, or sheet,” Hale says. “We compare the part geometry to the metal and see how close we are.”
If the part geometry is not a close fit to a stock metal size and volume, that may suggest that a better starting point might be investment casting, forging, or another process that produces a near net size and shape and reduces material costs and fixturing and machining times.
“The closer we can get to starting from near-net,” Hale points out, “the less metal we cut—and the more costs we save.”
Two subsequent analyses—one for forging and one for investment casting — each suggested possible savings (see Chart 1 below). Investment casting offered the most savings — 21 percent lower costs than the baseline machining estimate.
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The bar chart generated with DFM Concurrent Costing software compares what it would cost to manufacture the level by:
Machining (A)
Forging (B)
Investment casting (C)
The software demonstrates that investment casting would reduce costs by 21 percent. Aztalan and its customer have continued exploring cost reductions for the level, moving from an investment casting to either a pre-machined extrusion or a pre-machined forging.
Ongoing Processes
Aztalan has continued working with its customer to explore cost reductions for the level—everything from different processes to ordering near-net extrusions out of China. DFMA remains part of that process (see Table 1 below).
.jpg?n=1388 "DFM Concurrent")
“DFMA is a great addition to the services we offer,” Hale says. “When we first purchased the software, I assumed we’d be using it as part of supplier/OEM negotiations. Now it has an important role in how we approach our machining business, from quoting and manufacturing right through to post-op.”
One of Aztalan’s goals is to share its machining and DFMA expertise with customers at the concept stage of product development, working with them to create optimized, readily manufacturable designs.
He notes, “The earlier we use the software, the more we can build in producibility and cut away their costs.”
Click here to read: It’s Simple: Part 1, which explains how DFMA works for quoting and analyzing manufacturing costs