Any veteran machinist has stories of laughable part designs. Parts with impossibly deep hole callouts, dead-sharp internal corners and grooves wider than the Grand Canyon. Design engineers love to dream up impossible-to-cut part geometries. It might sound harsh, but those engineers sometimes learn the hard way how not to design machined products.
In his book “Design for Manufacturability and Concurrent Engineering,” David M. Anderson, fellow at the American Society of Mechanical Engineers, wrote, “Design for manufacturability is the process of proactively designing products to (1) optimize all the manufacturing functions: fabrication, assembly, test, procurement, shipping, delivery, service and repair, and to (2) assure the best cost, quality, reliability, regulatory compliance, safety, time to market and customer satisfaction.”
That’s a mouthful. What it means depends on whom you ask. Engineering, cost accounting, logistics and quality departments each have their own version of the truth. To the people in the shop, it’s simple. Design for manufacturability (DFM) means making parts easier and faster to machine and, therefore, more profitable.
Anderson suggests a number of no-brainer techniques: design parts that can be made in a single operation, avoid interrupted cuts and complex part geometries, specify reasonable tolerances and surface finishes, understand workholding principles and design features that can be cut with standard tools. Sounds great, but how does one learn how to design a more machinable mousetrap without first spending years in the shop?
DFM software is part of that answer. Brian Rapoza, R&D manager at Boothroyd Dewhurst Inc., Wakefield, R.I., explained how his company’s software helps designers estimate the costs associated with decisions made during the part design process and identify the potential for reduced cost and improved quality.
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