Most engineers know intuitively that an efficient product design that minimizes part count will save time and money on the production floor. But Mike Shipulski, director of engineering at Hypertherm Inc., a Hanover, N.H.-based manufacturer of plasma arc cutting systems, has the numbers to prove it.
When a Hypertherm team led by Shipulski designed a major new plasma cutting machine several years ago, the team was able to reduce the number of parts required to about 700, down from around 1,400 in the previous generation design. The result was a machine that took about four hours to build, compared to 10 hours for the previous unit, enabling Hypertherm to hit its 35 percent cost reduction target for the system.
Since that time, Hypertherm has applied the same design methodology—known as design for manufacture and assembly, or DFMA—to several additional products, all with similar results. “With one major subsystem, we saw a 90 percent reduction in labor, going from 10 hours to one,” notes Shipulski. Across the board, the DFMA initiative has produced a 300 percent increase in profit per square foot of factory floor space, he adds.
Start with DFA
Much of the initial savings comes through DFA, or design for assembly, by itself, Shipulski says. DFA focuses on reducing part count and complexity, while DFM, or design for manufacture, targets the manufacturing methods used to produce the parts, he notes. Shipulski recommends that manufacturers initially perform DFA alone on a new product design, then launch the product. DFM can then be applied in subsequent design efforts as a way to improve the design further, he says, targeting only those components that prove to be the most costly or time-consuming to assemble. This approach “avoids doing DFM on parts that you should have eliminated in the first place with DFA,” Shipulski explains.
The Hypertherm team tackled its initial DFMA project in 2001 using manual methods that Shipulski learned in engineering graduate school in the early 1990s. But for subsequent designs, the company is using DFMA software supplied by Boothroyd Dewhurst Inc., of Wakefield, R.I. The software provides tools for use in analyzing and understanding the cost effects of design decisions, with an eye toward reducing the manufacturing cost of a product during the design phase through product simplification and cost estimation.
Hypertherm isn’t the only company that has successfully reduced costs through the DFMA methodology. Indeed, the company was one of 19 Boothroyd Dewhurst DFMA software users that participated in a survey sponsored by the vendor last fall aimed at assessing the benefits of the approach to users. Besides Hypertherm, participating companies included Boeing, Dell Corp., GE, Harley-Davidson, KPMG, Magna Intier Automotive Seating, MDS Analytical Technologies, Motorola, Raytheon, Solectron (now Flextronics), Trane and TRW Automotive.
As part of the survey, participants were asked in which of 15 categories their companies have measured savings in overhead costs related to DFA part-count reduction. The largest number—13 of the 19, or 68.4 percent—cited production throughput savings. More than 47 percent cited factory floor space savings, while about 42 percent said that DFMA has produced savings in supply chain management.
Other top categories can be seen in the chart on this page. In addition to taking the survey, representatives from some of the companies participated in a roundtable discussion about DFMA, the text of which was published as part of the October 2007 report. One of those participants, Jay Mortensen, a cost optimization professional at KPMG, summed up the benefits. “DFMA can reduce costs and time-to-market by identifying opportunities early in the process when actions are easier to take.
The standardized DFMA process provides a conduit for communication within the organization and the supply chain. It also provides a means for identifying the financial impact of an efficient design,” said the KPMG representative, who is also a former director of target costing for Maytag, and was a Kaizen engineer for Toyota.
A copy of the full survey and roundtable report can be downloaded on the Boothroyd Dewhurst Web site at www.dfma.com/downstream.