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1 " lean " and the toyota production System Robert W. Hall any companies emulate the toyota ufacturing," a descendent of TPS made M production System (TPS), but there's only one original . toyota 's. Each toyota location has its own popular by the lean Manufacturing Comparing the offshoots with the personnel and process history, so each rootstock is inevitable when attending learning journey has assumed a local fla- "Overview of the toyota production vor. To prevent the system's DNA from System," a workshop being given twice a being corrupted, a "mother plant" sows its year for AME audiences by TSSC, a toyota TPS seeds in each new toyota location, subsidiary. The biggest differences relate to almost always a green field site. Most how TPS, much more than lean , empha- toyota experience converting another sys- sizes developing people to solve basic tem to TPS is with suppliers and other com- process problems. panies they have assisted. Whenever toyota transplanted the Process Mapping vs.

2 True North system to other companies, variations lean implementations are likely to appeared; no toyota supplier has DNA. start with overall process flow charts called identical to toyota . As others re-interpret- Value Stream Maps, a term attractive to the ed TPS, variations became more distinct. dollar minded. These help leaders visualize Some of these have clustered in " lean man- how to proceed with implementation. First they construct an "as is" flow chart, some- times opening their eyes to how much waste lards their operations. Then they construct a "to be" chart representing a slimmer, trimmer future. Comparing the In Brief "as is" with the "to be" chart generates a vision for implementation, including a few driving performance indicators. They also Differences between the toyota production System, as practiced by toyota , identify big blobs of muda as initial targets and lean manufacturing are significant. Two of those are that TPS empha- for kaizen event teams.

3 Sizes worker development for problem solving and spends much more time The charts also prompt up front strate- creating standardized work, which lean seldom incorporates. gic decisions. What will be the effect on capacity, employment, and cash flow? Why 22. Target Volume 20, Number 3. kaizen processes that should be outsourced customer in a million receives a defect, or eliminated entirely? For example, com- we're not at True North zero unhappy panies have found that, in modest volumes, customers. The same rigor applies to zero printed circuit boards can't be made on-site waste and lot sizes of one in sequence. Of competitively if waste were zero can't course, toyota rarely reaches absolute afford the capital and can't keep up with zero, but going for it prevents complacency the technology. about performance that is great by other Guided by Value Stream Maps, man- people's standards. As long as toyota is agement leads the implementation. Overall south of True North, they have problems to goals are quantified as indicators for a work on somewhere.

4 "dashboard" to track progress toward the The purpose of TPS is not rapid mate- vision. Kaizen events then start attacking rial per se, but process visibility. Smooth sub-processes. Staff are likely to direct the flow is only one factor that makes it easier attacks. to spot that one-in-million problem. toyota doesn't start with Value Stream Visibility spotlights the teeniest little bits of Maps. Initially they marshal the changes in waste, prompting more kaizen. Of the sub-processes by heading them all True seven classic wastes, toyota deems over- North. "Material and information flow" production the most serious; any of the charts appear much later to link processes other six may begin with that one. and march them along together. Because deployment depends on each True North is what we should do, not site's history of processes and working cul- what we can do, the ultimate ideal for the ture, neither toyota nor lean practitioners overall process, and for every sub-process employ unwavering formulas for it.

5 Within it. There is no other vision. Point However, toyota 's "creates" TPS. lean every person and every sub-process True practitioners more likely "implement lean .". North; once they are all loping along in the toyota stresses that TPS is human develop- same direction, they will easily merge into ment. lean organizations frequently try to a common takt time. That is, toyota grubs stretch the worker-to-supervisor ratio. the waste out of sub-processes before link- toyota keeps foremen or team leaders, con- ing them closely. verting them into coaches and backups for In Figure 1, both human development workers. However, everyone agrees that and process revision (for customer satisfac- the human side, learning new patterns of tion) are trekking True North. The word working and thinking is the highest hurdle. selection of the last bullet point under "human development" intimates more. lean Implementation "Professional development," by direct expe- rience more than formal training, inter- In a lean implementation, leaders as twines with process improvement.

6 Well as workers may be feeling their way, Everyone, including all workers, learns coaching less from experience than discov- how to solve problems and improve ery as you go. Sensing that the work cul- processes. If someone else does it, then ture must build up to lean , leadership may "turns the process over to production ," first do something to engage people in workers are ill prepared to continue kaizen problem solving, become familiar with on their own. To become professional process visibility, and improve teamwork as workers in this sense, they should experi- a way of life. For example, they may insti- ence how and why their process was devel- tute 5S before starting cell building, and big oped. TPS grows people in all their talents cultural leaps, like moving from an inde- even some they didn't know they had. pendent craft tradition, can be painful and On the customer satisfaction side of time-consuming. A few go "cold turkey" to Figure 1, the ideals of True North are cell building.

7 Absolute. Zero defects means zero none. But once they begin integrated opera- Not even Six Sigma is good enough. If one tional conversion, lean leaders convert 23. Third Issue 2004. Heading for True North Figure 1. The toyota concept of heading for True North. Value Stream Maps into to key process Staff and management almost always measures and blitz processes with kaizen direct a lean conversion. Usually, a con- events. Kaizen teams may pounce on sultant more experienced in the journey some fat targets first, but to integrate the guides them at first. Workers participate, effort, they usually start at final assembly and one objective of most kaizen events is and work back, setting up work to flow, as to give them first hand experience learning in a cell. They calculate takt times and bal- and using the tools of process improve- ance station workloads to them. Often, but ment. Training varies, but almost all com- not always, conversion is kaizen event by panies add instruction in lean techniques to kaizen event, each one addressing prob- the formal training of all employees.

8 Lems that plug workflow, such as quality, Being sidetracked by current operating setup times, maintenance, training, sched- pressures is always a hazard, but with per- uling system, and so on. Pull systems start sistent top management leadership, within tying the flow of operations together. a year or two most work flows by a pull sys- 24. Target Volume 20, Number 3. tem from door-to-door. With most of the flow. Set up local flows to produce only the initial heavy moving over, a plant may quantity needed when needed. Any pull declare itself lean , although there is much systems between areas are simple, like more to do. Improvement never ends. min-max kanban squares. The emphasis is Management raises the vision, refreshes on condensing cells and layout; cutting the indicators on the "dashboard," and setup times; minimizing lot sizes. Where drives again, this time extending the effort possible go to one-piece flow with no stock beyond the plant into product design, engi- between stations.

9 Doing this effectively neering, office work, perhaps even sales requires mastering multi-functional work and suppliers. While every case is unique, and group problem solving. Keep this up this general theme describes many sus- until the workforce does it routinely. tained lean conversion stories. Quality problems always lurk in prod- uct, in equipment, and elsewhere. Learn to build quality into each step of a process. TPS Creation Eliminate inspections using andons, poke Conversion concentrates on the shop yoke methods, and so on. Shorten the floor, led by veterans of the system, rela- feedback time for correction by cell build- tively sure of where they are going. Key ing, juxtaposing workstations, and cutting process measurements are quality and lead- the inventory and leadtimes until process times. The shop floor rarely sees unit cost variation is reduced because machines stop measurements. If muda is disappearing, (or beg for adjustment) before a defect is costs will come down; it's that simple.

10 Plant actually made. Doing this deepens the vis- efficiency is defined as ability to meet exact ibility, expanding the opportunities for customer requirements with minimum problem solving. resources: people, leadtime, and space. (It Start separating the work of people may have extra equipment.) toyota 's logi- from that of machines; workers learn to cal pattern is to introduce tools to increase tend multiple machines. Develop them to process visibility, gradually stepping up the make maximum use of their abilities, effectiveness of problem seeing and prob- adding value with every touch, rather than lem solving. When people and process are wasting time merely monitoring machines ready, move on. or inspecting parts. People may balance Stabilization: Stability is the depend- work cycle times, but we have not yet got- ability of man, machine, material, and ten to takt times. method, the classic old 4Ms. The first Standardized Work: This is the big dif- objective is to convert people from fire- ference between TPS and lean , begun while fighting to deliberative problem solving.