JAGUAR REDESIGNS ITSELF AS IT DESIGNS THE XK8

 

For all that is traditional in the Jaguar XK8 -- the burl walnut, the Connolly leather and its combination of elegance and power -- the new sports car was born of a process that was quite untraditional for the British carmaker.

The XK8 was the result of a rigorous development process stretching back two and a half years. The time it took Jaguar to develop a car -- that is, the time between the approval of a vehicle program by management and the date the car went into production -- was streamlined dramatically for the XK8. As a result, the product development process at Jaguar today is fully competitive within the auto industry. Only by reworking the entire procedure could Jaguar keep on track with its ambitious future model plans.

The XK8, known internally as X100, is the first Jaguar developed using the method known as World Class Process. This represents a fundamental shift from earlier times, when a new Jaguar sports car was to a large extent an outgrowth of competition successes, in the way that a trio of victories by the Jaguar D-type at the 24 Hours of Le Mans in the 1950s evolved into the E-type production car of 1961.

Today, the gestation period between initial concept and in-the-metal reality involves tens of thousands of decisions, all of which must be coordinated among numerous divisions within the company as well as independent suppliers and motor vehicle rules makers around the globe.

First a Target, Then Styling Development

Of course, the first thing people notice about a new model is new styling, but this stretch of the road to market is neither the first to be covered nor does it consume a great span of the development time. Even the early styling sketches are preceded by considerable legwork by the market research group, which is responsible for defining customer desires and expectations in terms of size and intended uses.

The initial drawings for the XK8 were penned within six weeks early in 1992, at which point several clay models were begun.

"Overall, we strive to bring obvious links with the past, but without copying," said Jaguar Director of Styling Geoff Lawson. "The heritage of good design is like DNA--it must be traceable through history, but not necessarily an exact duplicate."

The XK8 penned by Lawsonís team evokes its lineage with subtlety, reinterpreting but never lifting whole details from earlier examples of the marque. The oval "mouth" and prominent headlamps, for example, recall but do not duplicate the shapes of Jaguarís historic racing prototypes.

Final sign-off of the "theme decision" for the XK8ís body style took place in October 1992, some ten months after the first drawings were sketched. But even artists must adhere to the realities of development schedules.

Lawson explained: "The design of the XK8 needed to be flexible enough to incorporate refined styling without compromising World Class product development. Bumpers, lamps and instrument panels, for example, are critical, complex items requiring long lead times. Items like road wheels and badges, on the other hand, are relatively quick to tool and can be approved fairly late in the overall program."

Compressing the Schedule with Simultaneous Engineering

One hallmark of the World Class development process is the use of simultaneous engineering teams, enabling disparate engineering functions to advance without waiting for previous steps to be completed. As an example, by agreeing to specific targets for external size and power output, the engine team progressed with its work even before knowing how much room there would be under the hood of the XK8.

The development of the XK8 engine, called the AJ-V8, actually stretched over a longer period than the car program. The engineering studies which eventually led to the AJ-V8 began in the mid-1980s. The core design team was established in 1989 and the first prototype roared to life in November 1991.

Rigorous benchmarking of Jaguarís competitors was a key part of the XK8 development. This information, together with market research, led to performance targets for quality, power, smoothness, fuel efficiency, weight and overall size.

Another key to delivering a powertrain with leading-edge technology lay in identifying component suppliers with the very best quality and innovation. By involving them at the earliest possible stages, Jaguar took full advantage of their expertise.

December 1993: The Clock Starts

Formal go-ahead for the X100 development program was given in December 1993, after the Jaguar Board of Directors sampled a prototype car in Coventry, England. At this point, work shifted into overdrive, with specific goals for each stage of development. The steps were separated by built-in checkpoints, at which progress was checked against the agreed goals. These "gateway reviews" required sign-off by each stakeholder in the process before work could proceed on the next stage.

Computer-aided design techniques were used throughout the process to optimize the body structure for high strength and minimum weight, while computer-modeled simulations helped to compress development schedules with test cycles that reproduced conditions as severe as a 25,000-mile high-speed run on the autobahn. In the course of all this evaluation, every operating mechanism, from the sound of the exhaust system to the closing of the convertible top, was continually refined.

Throughout the design process, the teams worked together to optimize each part for efficient manufacturing and accurate assembly. And because the teams naturally grew accustomed to their areas of responsibility, special "Fresh Eyes" teams came in periodically to point out potential trouble areas.

Among Bob Dover's responsibilities as chief program engineer for the XK8 was keeping the project's focus while maintaining flexibility.

"We started with a mission statement that identified from the customer perspective what we should deliver. From that we reached our agreements of the project goals, a contract really," Dover said. "From then on, we continually measured our progress against the plan. Of course, the process was continually evolving. It wasnít written on huge stone tablets."

Mechanical prototypes addressed the physical issues of the entire package, right down to solving the problems of how to install a top-notch stereo with the most efficient use of space.

Next built were durability prototypes, to test every system at harsh extremes of weather, road surface and customer usage. Evaluation prototypes followed, in which initial tooling for assembly could be tried and compliance issues--such as crash testing--were examined. Finally, verification prototypes confirmed the accuracy of production tooling and rechecked earlier tests of safety and durability.

Quality on the Line

The XK8 represents a new era for Jaguar in terms of quality of the body panels, consistency of assembly and fit at seam gaps. A primary reason for this is the application, for the first time at Jaguar, of a system known as No Adjust Car Build (NACB).

This production technique uses master location points on the body to measure and align body panels. By using just a few master location points -- rather than many indexing locations -- variances cannot add up from panel to panel and result in poor fit.

The NACB process also compensates for manufacturing realities that once were common sources of fit and finish problems, such as the wear of dies and stamping tools and the natural tendency of metal to spring back a small amount after stamping.

The higher degree of accuracy enables panels to be built with fastener holes precisely positioned for an exact fit, rather than providing oversize slots for adjustment. Components are engineered so that they will fit correctly -- or not fit at all.

The metal-forming technology also yields an extremely high surface quality, providing an ideal foundation for the rich, glassy smooth paint finish of the XK8.

A further contribution to the high quality of the XK8 came from the use of actual production tooling to build the prototype vehicles used in early engineering evaluations. This made it possible to verify the manufacturing process and assembly quality at a much earlier stage, resulting in more precise fit and finish.

The success of the new processes at Jaguar will be tested ultimately by the buyers of the XK8, but Jaguar team members are convinced of its worth. Already, other teams are applying the process and the lessons of the X100 development to Jaguars of the future.

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