Handling engineering changes in automotive parts

Changes in design, material, manufacturing methods, performance requirements, or even packaging are facts of life for all manufactured products. Coordinating these changes to ensure smooth implementation is an important function for most manufacturing companies; it becomes even more important when two or more companies are collaborating on a complex assembly, such as an automobile.

A major identified problem for both original equipment manufacturers (OEMs) and their suppliers is an industrywide cultural requirement to do more with less. Everyone wants to manage with data, but sometimes collecting more data is detrimental to the process of correcting a problem.

Control of engineering changes requires cooperation and communication among groups within a company, as well as with outside suppliers.

Why Make Changes?

While manufacturers strive for perfection, all have faced that moment when they realize their shiny new product is not perfect. That is when engineering change comes into play.

Common reasons for making changes include dimensional issues, durability concerns, cost, quality requirements, performance requirements, and related changes to other components (see Figure 1). Any of these reasons can apply at any point in the life cycle of a product. In the case of automotive products, the life cycle commonly spans a decade, with a burst of activity occurring every year at model changeover.

Figure 1 Common reasons for making changes include dimensional issues, durability concerns, cost, quality requirements, performance requirements, and related changes to other components.

Change Initiation

Depending on the life cycle of a product, changes are likely to be initiated for different reasons at different times. Broadly speaking, products go through several phases in the course of a life cycle:

1. Conceptualization, design, and development
2. Launch
3. Production
4. End of life

In the automotive industry, vehicle development can take from three to more than eight years.

Conceptualization, Design, and Development. Speaking of engineering changes in the early parts of this phase is somewhat redundant—change is the entire reason for the new product. During this phase of a product's life cycle, change controls are likely to be minimal. This is the time when collaboration and communication between suppliers and OEMs need to be constant.

One problem that seems endemic in the automotive development process is the last-minute engineering change. Such changes not only disrupt program timing, but also inflate costs. So why does the U.S. automotive industry allow it?

• Cost reduction— The need for cost reductions often is not recognized until late in the engineering process. Also, cost quotations generally take place at an early design stage in the product conceptualization and development phase. While the product design might not meet all performance requirements at this phase, product content and cost will likely increase when all the requirements are considered.
  
  
• Perceived lack of competitive features— One of the root causes of this issue is a failure to think of technology as a competitive weapon. This is a factor not only in products, but also in manufacturing processes.
  
  
• Ego— Upper management usually has final approval on vehicle concepts and features, but often with little time to review them. Such reviews often take place just before or after program milestones and can lead to major and minor shifts in program direction, both of which are disruptive.

Launch. The launch of a new product is one of the most challenging activities in which an OEM or supplier participates. While change control is perhaps most crucial at this point in a product's life cycle, it also is the most difficult and chaotic at this stage.

Production. After product launch, the pace of official engineering changes slows; the emphasis becomes meeting production requirements. However, changes don't stop. Most products and processes undergo continual, low-level changes to improve quality and productivity and to reduce costs.

Indeed, the automotive industry has recognized and taken advantage of this continual change by requiring suppliers to provide "givebacks," long-term agreements, material cost reductions, and other savings. Given the high degree of competition required to win the award of a program, such improvements are vital if the supplier is to achieve and maintain reasonable profitability.

Paradoxically, the tweaks performed during a production run are rarely captured and documented as thoroughly as the changes performed during the initial design or at scheduled model changeovers.

End of Life. A product's end-of-life stage can be approached in several ways. If the product does not meet expectations in performance or sales, and company management has no interest in it, the result generally is an ignominious death. If the product does meet overall expectations, targeted changes can be performed to extend its life or prepare for its replacement. End of life also can be a good test bed for future product and process innovations.

Cradle-to-grave program ownership is a common aspiration in the automotive industry, but it rarely is carried out. Given the length of most automotive programs, as well as budgetary constraints and the development of new products, it is difficult to keep a core team intact and responsible for a single program.

Figure 2 Increases in computer and networking power availability and accessibility have strengthened automakers' communications infrastructure and product data management practices significantly. Source: United Kingdom Department of Trade and Industry.

Change Communication

In automotive design and production, which involves coordinating the activities of hundreds of companies and thousands of people, communication assumes paramount importance.

Over the past several years, with the vast increase in computer and networking power availability and accessibility, automakers have strengthened their communications infrastructure and product data management (PDM) practices significantly (see Figure 2). However, a serious disconnect still exists among a company's design, engineering, purchasing, sales, logistics, manufacturing, accounting, quality, and service departments and suppliers.

One area of communication difficulty is the transfer of responsibility between groups as a program moves between phases.

The conceptual phase, often the responsibility of an advance design group, defines the bulk of the end product cost. The program then is handed off to the product development group and developed internally or by a supplier. This transition, even under the best of circumstances, creates discontinuity in the design because many of the underlying reasons for selecting a solution or design approach are lost. A similar discontinuity occurs in the hand-off from product development to manufacturing.

Implementing launch teams can mitigate this to some degree, but it also introduces some problems. Launch teams are groups of technical and support personnel responsible for ensuring that the start of production for a product is successful. The teams generally consist of members of the product development team and sometimes include specialists in various disciplines needed for the production start-up phase of a program.

One difficulty associated with launch teams is simple human nature. The manufacturing plant personnel assigned to the new program often retain their responsibility for existing programs. Because the launch team is responsible for the new program, the plant personnel pay little attention to it. This leads to another discontinuity in the transition of the program.

Change Implementation and Verification

Each time an engineering change takes place, common human factors should be given high attention. In the automotive industry, engineers and designers often work exclusively in the product design area. This leads to a lack of appreciation of the realities of the plant floor, often resulting in problems such as difficult part assembly.

Four common errors can be minimized through careful design and planning:

1. Errors of commission. A change was implemented incorrectly.
2. Errors of omission. A needed change was omitted.
3. Sequence errors. Sometimes errors are introduced into the process by performing planning, validation, and verification steps out of order.
4. Timing errors. Sometimes a reasonable action performed at the wrong time can create more problems than it solves.

One design technique to help minimize these errors is to use standard parts. The chance of an assembler picking the wrong part is less if there are fewer different parts in the assembly. Commonality programs encourage widespread use of the fewest types of parts throughout the assembly.

Another technique is to make part differences very obvious. Different material or internal features may not be obvious to workers. If parts cannot be identical, their differences should be made obvious.

Parts also should be designed so that, even if the operator picks up the wrong part, it will not fit in the intended position. And if the operator chooses the right part, it should not fit unless oriented correctly. This can be ensured with poka-yoke, or error-proofing, geometries.

The design activity must include verification of the product. This encompasses not only the functionality of the components or system, but also the process used to generate specifications and requirements. As an example, it is of great importance that most automotive components be reliable, but it is vitally important for other components. Yet it is quite common for design specifications to fail to differentiate between the importance of components. The result often is a test plan that greatly increases both development cost and selling price.

Engineering changes are an unfortunate necessity in every industry, and change control is an ongoing problem. Following are a few points to keep in mind when you examine your processes:

1. Conserve the knowledge of the organization, and make plans to transfer information and experience in an orderly fashion. Management sometimes believes this is accomplished by having a process in place, but there is no substitute for mentoring and shared experience.
   
   
2. Being lean doesn't just imply doing more work with fewer resources. Lean organizations are those that pay attention to maximizing the value of their product through their process.
   
   
3. Strike a balance between evolutionary and revolutionary changes—both for your products and your processes. Sometimes a small tweak can be the difference between success and failure, while other times the only rational solution is to start over.
   
   
4. Don't make decisions without data, but don't let a lack of data paralyze you when you must act.
   
   
5. Measuring your improvement through the processes is key. To communicate your progress throughout the organization, talk in the language of business—money.

Chuck Stuart is a senior product engineer with a Tier 1 automotive supplier, cgstuart@gmail.com. S. Manivannan (Mani) is quality coach/assessor — PTO quality, Ford Motor Company, Manufacturing Process/Product Support Department, Rouge Office Bldg., Cube #3468G, MD #R-33, 3001 Miller Road, Dearborn, MI 48120-1496, 313-323-7719, fax 313-323-7719, smanivan@ford.com. Both authors also are doctoral students at Lawrence Technological University, Southfield, Mich., www.ltu.edu. Manivannan also is a member of The FABRICATOR Editorial Advisory Board.