On the Road to `Lean Production' of Automobiles

THE MACHINE THAT CHANGED THE WORLD, By James P. Womack, Daniel T. Jones, & Daniel Roos. New York: Rawson Associates. 323 pp., $22.50 MOST of us think of cars primarily from a consumer's point of view. How carmakers design and build automobiles is not a big concern. Yet perhaps it ought to be.

Twice in this century, the motor vehicle industry has revolutionized the way people make things, say authors James P. Womack and Daniel T. Jones, both of the Massachusetts Institute of Technology, and Daniel Roos of England's University of Sussex. Hence the title of their book: ``The Machine That Changed the World.''

In 1914, Henry Ford's Michigan assembly lines pioneered mass production, which soon cut car prices by two-thirds.

Now comes ``lean production,'' a name the writers chose because it ``uses less of everything compared with mass production - half the human effort in the factory, half the manufacturing space, half the investment in tools, half the engineering hours to develop a new product in half the time.''

The method, they add, ``provides better products in wider variety at lower cost. Equally important, it provides more challenging and fulfilling work for employees.... It follows that the whole world should adopt lean production as quickly as possible.''

The book attempts to pave the way for this transition with its thorough description of the lean production methods developed by Japanese companies, beginning in the 1950s. During the past five years, the authors visited carmakers in Europe, Japan, and the United States, comparing not only assembly-line work (which accounts for just 15 percent of the total human effort involved in making a car) but also product design, management, and relationships that assemblers develop with customers and suppliers.

The differences between mass production and lean production often relate to different concepts of the worker's role in the organization.

Mass production supplanted craft production by introducing the complete interchangeability of parts and the extreme division of labor. Even before the moving assembly line was introduced, Ford had cut the time an employee worked before repeating a task from 514 minutes to only 2.3 minutes. With simplified tasks, workers became interchangeable, too.

Lean production, while not abandoning the assembly-line process, expands the worker's role, shifting responsibility and initiative as far down the ladder as possible.

Where the classic mass producer would view error as inevitable (for example, setting levels of defects that parts delivered from suppliers may contain), lean producers set a goal of perfection: zero defects, continually declining costs, and continually expanding product variety. A mass-production plant might devote 25 percent of its work time to fixing defects that had passed through the assembly process, while lean producers do virtually no rework, expecting that problems will be traced and solved along the assembly line.

Ironically, the system has its roots in part in a bitter labor dispute in which the family that founded Toyota tried to fire a quarter of its work force. The company was able to lay off the workers only after agreeing henceforth to guarantee lifetime employment and wages graded by seniority and tied to company profitability.

This trend-setting agreement forced Toyota to treat its workers as a fixed cost, and thus to make the most of them, whereas layoffs are common at mass production plants during periods of slack demand.

The authors suggest that the cyclical swings of the US auto market could in fact be reduced by the introduction of lean production, which seeks to avoid building up inventories beyond demand. General Motors Corporation's new Saturn plant, for example, will produce its cars for specific customer orders.

``The Machine That Changed the World'' is valuable as an in-depth look at the techniques that Japanese automakers have used so successfully.

The authors make a conscientious effort to write for a general audience, including anecdotes as well as analysis. Still, the reader must be braced for total immersion in a rather narrow topic. Although written in a style that is more inviting than a simple summary of research, the content is essentially academic.

Will the book cause US companies to begin guaranteeing lifetime employment for their employees? It seems unlikely. But the Big Three and other US companies will find it worthwhile to pay attention to the lean production methods described. `The Five Whys' System. From `The Machine That Changed the World' IF a glitch develops, whether on the assembly line or in the showroom, workers in a ``lean production'' corporation use a system called ``the five whys'' to ferret out the problem's cause. The following example concerns car assemblers who discover defective parts from a supplier company.

First, they discover that the defective part has been caused by a machine that cannot hold a proper tolerance. But the machine isn't the ultimate cause. So the team asks: ``Why can't this machine hold tolerance?'' The supplier's personnel report that it's because the machine operators cannot be adequately trained. The team members ask, ``Why?'' The supplier answers that it's because these employees keep quitting to look for other work, which means the operators are always novices. ``Why do workers keep quitting?'' team members then ask. The answer: ``Because the work is monotonous, noisy, and unchallenging.'' The ultimate resolution: to rethink the work process in order to reduce turnover. This at last, is the ultimate cause - almost always an organizational problem.