7/27/2019 5.LeanandtheToyatoproduction

http://slidepdf.com/reader/full/5leanandthetoyatoproduction 1/6

"Lean" and the Toyota 

Production System

Robert W. Hall

Many companies emulate the ToyotaProduction System (TPS), butthere's only one original — 

Toyota's. Each Toyota location has its ownpersonnel and process history, so eachlearning journey has assumed a local fla-vor. To prevent the system's DNA frombeing corrupted, a "mother plant" sows itsTPS seeds in each new Toyota location,almost always a green field site. Most

Toyota experience converting another sys-tem to TPS is with suppliers and other com-panies they have assisted.

Whenever Toyota transplanted thesystem to other companies, variationsappeared; no Toyota supplier has DNAidentical to Toyota. As others re-interpret-ed TPS, variations became more distinct.Some of these have clustered in "lean man-

ufacturing," a descendent of TPS madepopular by the Lean ManufacturingInstitute.1

Comparing the offshoots with therootstock is inevitable when attending"Overview of the Toyota ProductionSystem," a workshop being given twice a

 year for AME audiences by TSSC, a Toyotasubsidiary. The biggest differences relate tohow TPS, much more than lean, empha-

sizes developing people to solve basicprocess problems.

 Process Mapping vs. True North

Lean implementations are likely tostart with overall process flow charts calledValue Stream Maps, a term attractive to thedollar minded. These help leaders visualizehow to proceed with implementation. Firstthey construct an "as is" flow chart, some-times opening their eyes to how muchwaste lards their operations. Then theyconstruct a "to be" chart representing aslimmer, trimmer future. Comparing the"as is" with the "to be" chart generates avision for implementation, including a fewdriving performance indicators. They alsoidentify big blobs of muda as initial targetsfor kaizen event teams.

The charts also prompt up front strate-gic decisions. What will be the effect oncapacity, employment, and cash flow? Why

22 

Target Volume 20, Number 3 

In Brief

Differences between the Toyota Production System, as practiced by Toyota,

and lean manufacturing are significant. Two of those are that TPS empha-

sizes worker development for problem solving and spends much more time

creating standardized work, which lean seldom incorporates.

7/27/2019 5.LeanandtheToyatoproduction

http://slidepdf.com/reader/full/5leanandthetoyatoproduction 2/6

kaizen processes that should be outsourcedor eliminated entirely? For example, com-panies have found that, in modest volumes,printed circuit boards can't be made on-sitecompetitively if waste were zero — can'tafford the capital and can't keep up withthe technology.

Guided by Value Stream Maps, man-agement leads the implementation. Overallgoals are quantified as indicators for a"dashboard" to track progress toward thevision. Kaizen events then start attackingsub-processes. Staff are likely to direct theattacks.

Toyota doesn't start with Value StreamMaps. Initially they marshal the changes insub-processes by heading them all True

North. "Material and information flow"charts appear much later to link processesand march them along together.

True North is what we  should do, notwhat we can do, the ultimate ideal for theoverall process, and for every sub-processwithin it. There is no other vision. Pointevery person and every sub-process TrueNorth; once they are all loping along in thesame direction, they will easily merge intoa common takt time. That is, Toyota grubsthe waste out of sub-processes before link-

ing them closely.In Figure 1, both human developmentand process revision (for customer satisfac-tion) are trekking True North. The wordselection of the last bullet point under"human development" intimates more."Professional development," by direct expe-rience more than formal training, inter-twines with process improvement.Everyone, including all workers, learnshow to solve problems and improveprocesses. If someone else does it, then"turns the process over to production,"workers are ill prepared to continue kaizenon their own. To become professionalworkers in this sense, they should experi-ence how and why their process was devel-oped. TPS grows people in all their talents

 — even some they didn't know they had.On the customer satisfaction side of 

Figure 1, the ideals of True North areabsolute. Zero defects means zero — none.Not even Six Sigma is good enough. If one

customer in a million receives a defect,we're not at True North — zero unhappy customers. The same rigor applies to zerowaste and lot sizes of one in sequence. Of course, Toyota rarely reaches absolutezero, but going for it prevents complacency about performance that is great by otherpeople's standards. As long as Toyota issouth of True North, they have problems towork on — somewhere.

The purpose of TPS is not rapid mate-rial per se, but process visibility. Smoothflow is only one factor that makes it easierto spot that one-in-million problem.Visibility spotlights the teeniest little bits of waste, prompting more kaizen. Of theseven classic wastes, Toyota deems over-

production the most serious; any of theother six may begin with that one.

Because deployment depends on eachsite's history of processes and working cul-ture, neither Toyota nor lean practitionersemploy unwavering formulas for it.However, Toyota's "creates" TPS. Leanpractitioners more likely "implement lean."Toyota stresses that TPS is human develop-ment. Lean organizations frequently try tostretch the worker-to-supervisor ratio.Toyota keeps foremen or team leaders, con-

verting them into coaches and backups forworkers. However, everyone agrees thatthe human side, learning new patterns of working and thinking is the highest hurdle.

 Lean Implementation

In a lean implementation, leaders aswell as workers may be feeling their way,coaching less from experience than discov-ery as you go. Sensing that the work cul-ture must build up to lean, leadership may first do something to engage people inproblem solving, become familiar withprocess visibility, and improve teamwork asa way of life. For example, they may insti-tute 5S before starting cell building, and bigcultural leaps, like moving from an inde-pendent craft tradition, can be painful andtime-consuming. A few go "cold turkey" tocell building.

But once they begin integrated opera-tional conversion, lean leaders convert

23

Third Issue 2004

7/27/2019 5.LeanandtheToyatoproduction

http://slidepdf.com/reader/full/5leanandthetoyatoproduction 3/6

Value Stream Maps into to key processmeasures and blitz processes with kaizenevents. Kaizen teams may pounce onsome fat targets first, but to integrate theeffort, they usually start at final assembly and work back, setting up work to flow, asin a cell. They calculate takt times and bal-ance station workloads to them. Often, butnot always, conversion is kaizen event by kaizen event, each one addressing prob-lems that plug workflow, such as quality,setup times, maintenance, training, sched-uling system, and so on. Pull systems starttying the flow of operations together.

Staff and management almost alwaysdirect a lean conversion. Usually, a con-sultant more experienced in the journeyguides them at first. Workers participateand one objective of most kaizen events isto give them first hand experience learningand using the tools of process improve-ment. Training varies, but almost all com-panies add instruction in lean techniques tothe formal training of all employees.

Being sidetracked by current operatingpressures is always a hazard, but with per-sistent top management leadership, withina year or two most work flows by a pull sys-

24 

Target Volume 20, Number 3 

Figure 1. The Toyota concept of heading for True North.

 Heading for True North

7/27/2019 5.LeanandtheToyatoproduction

http://slidepdf.com/reader/full/5leanandthetoyatoproduction 4/6

tem from door-to-door. With most of theinitial heavy moving over, a plant may declare itself lean, although there is muchmore to do. Improvement never ends.Management raises the vision, refreshesthe indicators on the "dashboard," anddrives again, this time extending the effortbeyond the plant into product design, engi-neering, office work, perhaps even salesand suppliers. While every case is unique,this general theme describes many sus-tained lean conversion stories.

TPS Creation

Conversion concentrates on the shopfloor, led by veterans of the system, rela-

tively sure of where they are going. Key process measurements are quality and lead-times. The shop floor rarely sees unit costmeasurements. If muda is disappearing,costs will come down; it's that simple. Plantefficiency is defined as ability to meet exactcustomer requirements with minimumresources: people, leadtime, and space. (Itmay have extra equipment.) Toyota's logi-cal pattern is to introduce tools to increaseprocess visibility, gradually stepping up theeffectiveness of problem seeing and prob-

lem solving. When people and process areready, move on. Stabilization: Stability is the depend-

ability of man, machine, material, andmethod, the classic old 4Ms. The firstobjective is to convert people from fire-fighting to deliberative problem solving.First create increased visibility in the cur-rent process and expose problems, teach-ing people how to solve them using the fivewhy's and the Deming Circle — and givingthem their head to do it. Coach peopleearly and often to carefully observe anddocument what they are doing now. Givethem the means to habitually improve theirown work and the processes around them.Don't go to continuous flow if big problemswith quality, maintenance, or supply wouldbe overwhelming.

Continuous Flow: This is the big stepincreasing process visibility. The process isstill loaded with waste, but predictableenough that it won't choke on continuous

flow. Set up local flows to produce only thequantity needed when needed. Any pullsystems between areas are simple, likemin-max kanban squares. The emphasis ison condensing cells and layout; cuttingsetup times; minimizing lot sizes. Wherepossible go to one-piece flow with no stockbetween stations. Doing this effectively requires mastering multi-functional workand group problem solving. Keep this upuntil the workforce does it routinely.

Quality problems always lurk in prod-uct, in equipment, and elsewhere. Learn tobuild quality into each step of a process.Eliminate inspections using andons, poke

 yoke methods, and so on. Shorten thefeedback time for correction by cell build-

ing, juxtaposing workstations, and cuttingthe inventory and leadtimes until processvariation is reduced because machines stop(or beg for adjustment) before a defect isactually made. Doing this deepens the vis-ibility, expanding the opportunities forproblem solving.

Start separating the work of peoplefrom that of machines; workers learn totend multiple machines. Develop them tomake maximum use of their abilities,adding value with every touch, rather than

wasting time merely monitoring machinesor inspecting parts. People may balancework cycle times, but we have not yet got-ten to takt times.

 Standardized Work: This is the big dif-ference between TPS and lean, begun whilestill in continuous flow. Standardized workisn't only documentation. It's also animprovement process; layout; worksequence, and work methods. Emphasis ison human motion. To pace work, intro-duce takt times, and coach people to devel-op efficient work flow to a takt time con-sidering safety, quality, quantity, and cost(use of resources). Continue coaching untilworkers with their team leaders can gener-ate their own standard work. This usually takes the longest time, but Toyota consid-ers standardized work to be necessary tosustain the gains going True North, as illus-trated by Figure 2.

Because standardized work takes along time to mature, some Toyota plants

25

Third Issue 2004

7/27/2019 5.LeanandtheToyatoproduction

http://slidepdf.com/reader/full/5leanandthetoyatoproduction 5/6

are much better developed than others.Tell-tale signs:

• Near the work areas is evidence of 

worker problem solving, real things in

real time like scribbled flip charts, not

sanitized computer graphic summaries.• Work details at each station are crisp; 5S

is detailed, so you can identify morethan the main flows of material.

• Workers aren't moving at breakneckpace, but are so concentrated on valueadded activity that they've less time tobanter or even smile at visitors.

Thus TPS standardized work com-bines the disciplines of improving workwith that of holding the improvement,which sets up the ongoing elimination of waste that most lean implementations

never get to. Standardized work docu-mentation is but the script for a play, oftenrewritten, which all actors that substituteroles adhere to and help rewrite. Theunfolding play is the thing, the distant cus-tomer its unseeing audience.

Getting It All Together: Now orches-trate improvement toward True North. If anoverall takt time is at all possible, every-thing is connected with production of end

product using takt times and a pull system.(That's right; a detailed pull system goes inlate.) Plant workload is balanced with aheijunka box, container lot sizes, and stan-dard inventory at various points in the sys-tem. Decreasing inventories a bit here and

there stresses the system just enough toallow the workers, now capable of stan-dardized work, to press as a total grouptoward True North. Sustained visibilityshines light on every little pebble in thepath to True North, so every processimprover in every little nook of the totalprocess should see something to thinkabout and to work on.

 Summary 

Lean implementations, mapped and

planned, tend to be more "engineered" bystaff than TPS. If well planned, lean imple-menters may better anticipate businessissues, like increasing sales to absorb theidle capacity released from productivityimprovement. They may also anticipate thecultural changes that will be necessaryUnfortunately, not all are carefully plannedand some cultural changes, as for standard-ized work, are rarely anticipated at all. A

26 

Target Volume 20, Number 3 

Figure 2.

Relationship Between Standardized Work and Improvement

7/27/2019 5.LeanandtheToyatoproduction

http://slidepdf.com/reader/full/5leanandthetoyatoproduction 6/6

well-structured lean implementation may consider adoption of the tools to be a suc-cess, but allow people to remain underde-veloped in problem solving, and detailedprocess problems to remain hidden.

Paradoxically, TPS creation, while moreorganic and intent on developing people tothe max, just "bulldozes" through. TPS cre-ation starts immediately on the shop floor,developing people to unravel problems. TPStools are merely a method to change thework culture to problem solving mode, andTPS leaders may pay little heed to the cultur-al shock associated with this. The premise isthat workers have vast, untapped potentialwaiting to be tapped. Any system, IT or oth-erwise, that gets in the way of this goal is

discarded on faith that something better willbe invented from the chaos. To an extentrarely found in lean manufacturing, TPSdevelops people to concentrate unrelenting-

ly on machines, maintenance, quality,processes, or any other waste that stands inthe way of total customer satisfaction — True North.

 Robert W. Hall is editor-in-chief of Target and a founding member of AME.

 Footnote:1. The adjective "lean" was first used to describe

operations by Toyota and other Japanese auto com-

panies in The Machine that Changed the World ,

James P. Womack, Daniel T. Jones, and Daniel Roos,

MIT International Motor Vehicle Program, 1990. "Lean

manufacturing" rapidly became popular afterward.

27

Third Issue 2004

© 2004 AME® For information on reprints, contact: Association for Manufacturing Excellence www.ame.org