Projector Dfma

Boothroyd Dewhurst, Inc. Design For Assembly Software Case Study

Product

Overhead Projector

Company

3M

Source

"DFMA: Learning to Design for Manufacture and Assembly" Mechanical Engineering May 1992

Improvements/Reductions Product Development Cycle

45%

Summary Redesign of overhead projector.

BDI Case Study # EQP5

Automakers and other manufacturers using design for manufacture and assembly are relishing its fruits-shorter production times and improvements in product quality-while saving money.

Joseph Constance Wyckoff, N.J.

D

esign for manufacture and assembly (DFMA)-a management and software tool based on the premise that about 70 percent of all product development, assembly, and production costs are built in during the design stage-has been saving some companies production and labor costs for the last decade. The tool enables designers to consider a product’s material selection, design, manufacturability, and assembly up front. It also increases productivity and quality. Approximately 400 companies and institutions use it worldwide. At Ford Motor Co. (Dearborn, Mich.), for example, executives saved $1.2 billion worldwide using design for assembly (DFA) in l987 alone. And General Motors Corp. (Detroit) reportedly has reduced manufacturing costs 30 to 60 percent on certain projects since it started to use DFMA in late l989. GM has implemented a large program using DFMA and concurrent

engineering. While many automakers have embraced DFMA and benefited most from this manufacturing approach, it is also available to other industries. DFMA has enabled various companies to design, manufacture, and assemble products more efficiently and competitively. Makers of aircraft, industrial and electrical machinery, pumps, and compressors are among the growing number of manufacturers adopting the method. However, DFMA has caused some disruptions. Under this system, engineers and designers arc forced to work in teams rather than individually, and this occasionally creates friction. Additionally, their work is more closely scrutinized, as DFMA often reveals that their initial ideas may not be the most effective. DFMA, developed by Boothroyd Dewhurst Inc. (Wakefield, R.I.), calls for the development of detailed designs for each of a product’s individual parts, based on the combination of various capabilities and limitations inherent in the materials and processes used. That is, manufacturers must identify the most appropriate assembly system for a new product design in con-

70 / MAY 1992 / MECHANICAL ENGINEERING

junction with a structural analysis of the design for its overall efficiency and suitability for the chosen assembly method. DFMA runs on IBM PCs and on Apple computers. The minimum cost of licensing either DFM or DFA software, for a site with 250 employees, is $12,500. The DFMA software is a methodology and data base system that allows a design engineer or crossfunctional manufacturing team to analyze and rate product designs for ease of assembly and structural efficiency, as well as to predict assembly and manufacturing costs. The program allows for the selection of the most feasible manufacturing process at the concept stage, when product configurations are a rough sketch or outline and before CAD/CAM activity has begun. Putting DFMA to Use The Portable Compressor division of the Construction and Mining Group was one of the first divisions of Ingersoll-Rand Co. (Mocksville, N.C.) to use the DFMA tool, according to Don Gerhardt, manager of engineering and development. In the past, he explained, products were designed and preproduction units were built. Then 6 to 12

Instrument panel

Screw,

r

Control panel

Screw, nut

Relay

_

r Control panel

Valve, 2-way Decal-l

I. Lamp

Rivet

Cable, choke-

,

Door, control panel

d Rivet

Combined control and instrument panel

Fewer parts. At Ingersoll-Rand, DFMA software was used on a control and instrument panel assembly. The number of parts was reduced 33 percent; the number of fasteners used fell 38 percent; assembly operations decreased 33 percent; and assembly time improved 28 percent.

MECHANICAL ENGINEERING / MAY 1992 / 71

months were spent obtaining input from employees on how to optimize a prototype. But that all changed in 1987 when DFMA was adopted, said Gerhardt. “We have been able to reduce our new product development time from 2 years to 12 months while maintaining high-quality standards,” he said. “DFMA has been an important tool in uniting the project teams from various departments into a cohesive group.” Ingersoll-Rand began seeing the benefits of DFMA as soon as it began its training period, said Gerhardt. In a new radiator and oil cooler design used as a test, the number of parts was reduced 64 percent from 80 to 29; the number of fasteners was cut 47 percent from 38 to 20; assembly operations decreased from 159 to 40, a reduction of 75 percent, and assembly time decreased from 18.5 minutes to 6.5 minutes, a 65 percent improvement. In another instance, the DFMA software was used on a control and instrument panel assembly. Again, there were significant savings. The

number of parts was reduced 33 percent; the number of fasteners used fell 38 percent; assembly operations decreased 33 percent; and assembly time improved 28 percent. To convince engineers of the value of the DFMA approach, IngersollRand analyzed components not made with DFMA and showed company designers firsthand how the technique could improve designs. Gerhardt said engineers were more open to the concept once they were given concrete examples of improved designs. While it was good for the company as a whole to show its designers how they could improve their work, management had to soothe the egos of engineers who found that they were not producing the optimum designs. The key here, Gerhardt said, was to show how DFMA was not going to be used to criticize the engineers’ work, but rather to help them improve it. Teaming Up As soon as the training period was over, Ingersoll-Rand combined engineering and manufacturing ex-

72 / MAY 1992 / MECHANICAL ENGINEERING

perts into teams so that they would communicate with each other readily during implementation of DFMA. The most important element in successfully applying DFMA and concurrent engineering involves team building and proper team selection, said Gerhardt. A team leader must have the necessary technical skills, a sense of urgency and persistence, and the ability to deal well with people. Ingersoll-Rand team leaders have come from engineering, marketing, and purchasing groups. The company has learned that early supplier involvement provides several benefits. The overall cost of a product can often be reduced by working with a supplier and incorporating simple changes in a component, said Gerhardt. IngersollRand has invited suppliers to partake in DFMA training sessions as the company relies on them to take more of the design responsibility in areas in which they have the expertise. Ingersoll-Rand’s Portable Compressor division is currently using

DFMA concepts on several products: air compressors, portable generators, and portable construction lighting equipment. “The DFMA concept is becoming second nature to users,” Gerhardt said. “Initial designs are coming out with the best ratings even before running them on the software.” At Precor USA Inc., a maker of aerobic exercise equipment based in Bothell. Wash.. DFMA--initiated last year-is used to improve product quality and productivity and to enable the firm to estimate competitors’ overhead, labor, and material costs as well as the type of production process they use. George Henry, vice president of engineering at Precor explained that the company began its business in the early 1980s when there was not much competition in aerobic exercise equipment. But competition increased in the mid-1980s after medical experts revealed that exercise affecting the cardiovascular system could help fight heart disease and improve general health. “We had to find a way to keep our lead in the business, improve our time to market and get better products to market,” Henry said. “We also needed a way to benchmark competing products. DFMA enables us to design our products better and more quickly using lower-cost components. It gives us quantitative assembly times up front.” Precor’s DFMA team includes production, procurement, sales, marketing. and financial personnel as well as designers and manufacturing engineers. Henry said that involving employees outside the manufacturing and design area is important because if, for example, purchasing managers learn that a specific piece of tooling will be required for a new product, they can order it well ahead of production time. Currently, DFMA is being applied to about a dozen products under development at Precor. For one product, DFMA has enabled Precor to reduce the number of fastener types by 54 percent and total fabrication and assembly time by 36 percent. For another product, the number of fastener types was reduced 75 percent and total fabrication and assembly time was cut 27 percent. Improving Design With DFMA, Fibercraft//DESCon Inc. (Rochester, Mich.) was able to eliminate about 120 parts and 109

Less is more. Storage Technology Corp. used DFMA to reduce the number of par ts in this tape cartridge elevator from 95 (top) to 36 (bottom). MECHANICAL ENGINEERING / MAY 1992 / 73

fasteners in the instrument panel for the Oldsmobile line. Linda Shimkus, an instrument panel engineer at Fibercraft/DESCon, said that while redesigning the instrument panel and related systems, her “team went through the DFA process four times. The first time through we determined that the instrument panel was not a standalone component but an integrated system. The second time we went through the DFA process, we saw it as a complete system that crossed different technological areas.” These included electrical engineering and design, as well as heating, ventilating, and air conditioning engineering and design. “The third and fourth times through DFA, the instrument panel was a totally integrated highly functional system,” she added. Now there is less ergonomic stress on assembly plant operators-crawling in and out of cars during assembly was reduced 60 percent, and the number of times workers have to lie on their backs was halved. Also, the number of job stations at the assembly plant was reduced from 36 to 18. Gerald Morrison, DFMA manager at Fibercraft/DESCon said the key to implementing the system was the creation of an atmosphere that makes employees aware of why the technique is being used and what its purpose is. “The ‘why’ was survival. In this business you have to fight for your existence,” Morrison said. Once the proper atmosphere is created, the DFMA group must perform as a team, he said. “It is necessary to lose one’s identity and become part of the team and have a vision that is friendly to DFMA.” At the Codex division of Motorola Inc. Information Systems Group (Mansfield, Mass.), DFMA is used to optimize the design of the electromechanical enclosures on its line of modems and networking systems. T.B. McMichen, principal engineer of new products manufacturing, said DFMA enabled the company to improve assembly efficiency to 30 percent-previously it was at 15.9 percent-and decrease assembly time to 160 seconds from 1720 seconds; part/operation count fell to 31 from 271; and the number of fasteners decreased to 12 from 171. Meanwhile, Minnesota Mining and Manufacturing Co. (3M) in St. Paul uses DFMA to move new products to market in half the time it took before it implemented the system in 1989. Tom Moore, manufac-

turing engineering manager in the Hard Goods and Electric Support division, said that some areas of the company have been able to reduce the time it takes to commercialize a product by 40 to 50 percent. Part counts have been reduced as well, he said. The Hard Goods group has used DFMA to make overhead projectors and laser imagers used in medical imaging. Enhancing a product by reducing the number of parts offers several advantages, including fewer processing steps, adjustments, mating points, tolerance stack-up problems, operator frustrations, material control problems, and assembly fixtures, according to Moore. Typically, designers do not have a way to quickly evaluate the costs associated with alternative designs. Current cost-estimating approaches require detailed engineering drawings, creating excessive product costs and too many parts that end up being quality and reliability problems, said Moore. 3M assigns areas of expertise to members of the design team who have a specialty in a particular area, such as electronics or design. These specialists work concurrently with product designers to minimize manufacturing costs and optimize the product. In 1988, consultants recommended that Storage Technology Corp. (Louisville, Colo.), a manufacturer of tape and disk peripheral computer equipment, implement a qualityof-design program, said Arch Higgins, d i r e c t o r o f d e s i g n f o r manufacturing at StorageTek. After visiting the Ford facility to see the technique in action, about 1400 StorageTek employees were trained in the process during 1989 and 1990. Also trained were suppliers, since they can suggest ways to improve a design so that the optimum part can be made. Higgins said that by using DFMA, the company has streamlined components from about 90 parts down to 36 parts. StorageTek is now implementing DFMA on all of its more than 40 products. “By going through a couple of iterations on every product line that’s being developed, we’re seeing a reduction in total assembly parts and assembly time,” said Paul Casey, a design applications engineer at StorageTek. “From the lastgeneration product line to the current-generation line, it’s very typical to see things such as part count and number of operations cut in half.”

74 / MAY 1992 I MECHANICAL ENGINEERING

At NCR Corp.‘s engineering and manufacturing facility in San Diego, DFMA was used on the fourth generation of its 9800 on-line transaction processing and real-time computing system. These products are used by banks in their automated teller machines. Joe Fleming, senior principal industrial engineer at NCR, said the DFMA approach resulted in a 90 percent reduction in continuing engineering efforts after the first test unit was built; a 66 percent reduction in continuing engineering efforts after product release; and no assembly errors occurring on the first 10 units built. Also, 99 percent of all wire assembly labels were removed, resulting in fewer labeling errors and lower part cost. The number of operation assembly sheets was reduced 20 percent. Moreover, improved CAD drawings led to simpler written instructions on the products. Fleming said NCR has given the DFMA technique its own name, “DFX,” as a way to make clear that efforts should be made to improve not only a product’s manufacturability, but also its testability, reproducibility, marketability, and maintainability. This NCR division is currently applying DFX to its model 3600 large on-line transaction processing system. Failures Exist Not all of those who are introduced to DFMA find that it can help them, however. After analyzing some of their pen products with DFMA, engineers and designers at Bic Corp. (Milford, Conn.) found that, in many cases, the designs could not be simplified. So while DFMA is generally successful. there are instances when it cannot help improve the design efficiency or provide a way for a company to gain additional cost savings. Henry Leo, product designer at Bic, said the company’s pens contain many simple individual components that cannot be combined into one unit. Moreover, the parts are not complex shapes or assemblies that could be streamlined or made less complex by DFMA. DFMA developers Geoffrey Boothroyd and Peter Dewhurst said that the next step in the development of DFMA is to expand its focus to include the assembly of large components; the assembly and installation of electrical connections and wire harnesses; and the design of products that are easier to maintain and recycle. n