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Design's next step: Serviceability

DN Staff

June 26, 1995

7 Min Read
Design's next step: Serviceability

You may never be rid of your next design. Whether cars or capital goods, a changing economy means that more and more products are being leased. Products that are sold need ever-longer warranties to stay competitive. And environmental laws in some places already require manufacturers to take back worn-out products for proper dismantling and disposal.

Engineers looking at longer-term responsibility for their products have two choices: Design them so they'll never break, or more realistically, design them so they're easy to fix.

This trend can best be illustrated with actual product examples. The thread that ties them together: serviceability design extends the concurrent engineering and quality design practices many companies already have in place. The added brainpower needed to make them successful pays off. As the B-school graduates say, "it's not a problem, it's an opportunity."

Expanding markets. Ingersoll-Rand Co., Washington, NJ, lays claim to being the largest manufacturer of centrifugal air compressors in the world. Over the last five years, its Centrifugal Compressor Div. spent $30 million on capital improvements to its plant in Mayfield, SC. Quality rose to the point where, with predictive maintenance like signature analysis and periodic oil and water testing, its API-compliant compressors now go five years between overhauls.

Yet, for all the improvements, the company shied away from specialty applications in large chemical, petroleum, and other process industries. These one-off applications usually involve designing the compressor with ancillary equipment to contractor specifications. Although potentially lucrative, the ad hoc engineering entailed added costs with little residual benefit to the company.

The solution, says George Kopscick, product manager for engineered products, was a clean-sheet design effort involving engineers, manufacturing people, service personnel, and customer representatives. As he explains, "We asked what we could bring to market that nobody else does." The answer: less frequent, and easier system maintenance.

To make that happen, the team adopted a number of special design criteria. Among them:

Add space for unrestricted access to every major component.

  • Place all maintenance/adjustment features within reach of the outside edge of enclosures

  • Include consolidated, maintenance-free stainless steel reservoirs.

  • Require flange connections for all auxiliary components for easy replacement.

  • Make all lube-oil components bracket-supported to the base to prevent breakage.

Introduced last March, the Process Package Air Compressor features a range of options such as cooling and lubrication components pre-engineered to work together. For example, in applications using silt-laden river water for cooling, an external water-through-tube heat exchanger replaces the conventional internal cartridge configuration.

When the tubes become clogged with silt, workers simply remove two end bonnets and clean the tubes with rods or high-pressure water. Total down time: three hours compared with 24 or more to replace a cartridge. The design, says Kopscick, has prompted several petroleum manufacturers to abandon their internal specifications and request strategic partnerships with IR for the compressors. The new low-maintenance design required no magic, he adds. "We just asked our customers what problems they were seeing in the field, then we brought our knowledge to bear to solve them."

Improve customer loyalty. Roger Smith, former GM chairman, was roundly criticized in the mid-eighties for saying that the best alternative to a inexpensive foreign car was a used Buick. Perhaps he was just prescient. With today's higher car prices, many manufacturers tout their cars' quality, low maintenance costs, and resulting higher resale value. In fact, maintainability has become a major marketing tool.

The quest for customer loyalty also has lengthened automobile warranties. Volkswagen, for example, recently introduced a 10-year, 100,000-mile warranty on selected models. Tim Lintz, advanced service readiness team leader at GM's Cadillac/Large Car Div. (C/LCD), Flint, MI, puts it simply: "If we can assist with engineering a vehicle that's less costly to service, it will be less costly to the corporation to issue a warranty."

General Motors uses a codified approach to design for serviceability. Service Engineering forms a part of GM's four-phase Product Program Management Vehicle Development Process, its term for concurrent engineering. Each design engineer gets a copy of GM's 100-plus-page Serviceability Design Guidelines. In it, they find recommendations for best practices in engineering every component in a modern automobile, including such minutia as towing, shipping, and a vehicle's compatibility with automatic car washes. In addition, the company has a separate Service Technology Group. Its representatives meet with all platform teams as new-car development begins.

"We go through a bi-weekly "wall walk," where production-assembly documents are posted that show how we plan to build the vehicle," explains Lintz. In general, the simpler it is to assemble a vehicle, the easier it is to access a part for service later on.

GM design teams have two options for rating component serviceability. The company has proprietary software that estimates labor time and expense based on historical repair data. This option is used when preparing a business case for a particular serviceability design idea.

The company also uses a manual Serviceability Task Evaluation Matrix (STEM) for quick decision-making during engineering meetings. STEM criteria include estimated repair and maintenance time, part cost, diagnosis time, tool requirements, technician training requirements, and part availability (will it need a special order or can customers pick it up at K-Mart?). The matrix assigns point values in each area, and users compare the totals for design alternatives to help make a decision. Key to effective use of the matrix: knowledge of the competition. The Guidelines notes "a rating of 85 points for an oil-filter change may be worst-in-class, but 50 points for a transmission filter may be world class indeed."

Another problem complicates serviceability issues for auto designers. Some 70% of repair work is performed by local garages, not dealers. Companies can't control the quality of the independent mechanics, but the quality and cost of their repairs often reflects on the engineering of the car. Car companies disseminate service information as best they can. Likewise, engineers have to avoid designs that require unique tools or handling.

Electronic diagnostics spotlight the issue. The U.S. government requires manufacturers to share drivetrain troubleshooting codes with independent scan-tool makers. Where no mandate exists, as in body and chassis systems, proprietary communications protocols can blemish a good design's reputation with owners. "That's where we come in," says Paul Gallo, service readiness engineer at C/LCD. "We make sure that the data make it into service manuals."

Inevitably, service issues sometimes clash with manufacturing or product-specification goals. For example, automated laser welding of car bodies speeds assembly and improves chassis stiffness, an important ingredient in a rattle-free, well-mannered car. Unfortunately, separating laser-welded components damaged in a collision can be extremely difficult. In the give-and-take of concurrent-design meetings, serviceability advocates consider the company's competitive position and "what's right for the car," says GM's Lintz. "If we don't want a laser weld in a certain area, we support that with the time and cost of repair, and how it might affect the customer's insurance premiums."

Automating DFS. Building on the success of its Design for Manufacture and Assembly(R) (DFMA) program, Boothroyd Dewhurst, Inc. (BDI), Wakefield, RI, recently introduced Design for Service (DFS) software as a part of its DFA version 7.1. DFS calculates a serviceability index for a given design then walks engineers through "what-if" analyses to improve that rating.

Designers begin the serviceability analysis by entering a disassembly sequence of items and procedures into an interactive worksheet. This can be done manually or by importing items from a previous DFA structure chart. The software responds with questions as needed to flesh out the proposed procedure.

DFS incorporates a database with over 800 service events, including item-removal and insertion times, item- and tool-acquisition times, and component manipulation times. It uses that database to automatically generate a reassembly procedure and time estimate. Users then compare the estimates with design goals or with design alternatives.

With the software, designers can identify specific design problems that contribute to poor serviceability. For example, by comparing the part's expected failure frequency and impact with its service efficiency, they can quickly identify critical service shortcomings that contribute to owner dissatisfaction.

Peter Dewhurst of BDI explains, "DFS provides a systematic, quantitative method that allows users to step through the process and look at service tasks up-front-where problem, solutions, and costs can be recognized while change is still possible."

Is serviceability the last of the contending design criteria that engineers must face? No, says Dewhurst. Regulations and changing consumer attitudes will increasingly make recyclability an issue as well. Fortunately, serviceability issues, properly addressed, also will simplify recycling issues.

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