Get Your Boots On — A Close Up View of the Toyota Production System

April 8, 2009 Michael James

Genchi genbutsu sounds vaguely like “getcher boots on” and means “go and see for yourself.” My Japanese fiance is currently translating Taiichi Ohno’s original words in the book Toyota Production System for me, as the published English translation has some issues. But there’s nothing like actually seeing it, as I did this week at Toyota’s Takoaka manufacturing plant in Japan.

This plant makes about 500 cars per shift, two shifts per day. My first impression of the plant was that it looked nothing like a Toyota automobile! I was surprised to see a typical factory exterior with rust spots that clearly hadn’t been painted in a few years. (Taiichi Ohno wrote “If you are not careful, seisou and seiketsu can just make you use up a lot of paint.”) Also, could someone tell me why factories always have those slanted roofs?

The famous Toyota Production System (TPS) is the basis of “Lean Manufacturing” and also influences the Agile software movement. Is a production system relevant to new product development? Parts of it are and parts of it aren’t. Making a thousand cars per day in a finite number of configurations on a production line is different from inventing a new product that never existed before. Manufacturing concepts have been misapplied to software development for decades, and we run that risk with Lean and TPS. But I think you will enjoy a quick glance of TPS in action.

JIT — Just In Time

Kiichiro Toyoda instructs us to make only what is needed only when it is needed and only in the amount needed, starting with the customer order.

The Toyota Production System is customer driven. It starts with a customer order, then orders ripple through the supply chain using a kanban system. Kanbans ripple out to suppliers of suppliers. Each process is the customer of the preceding process, and only make parts actually consumed, in response to orders. Each parts supplier also keeps a *small* outgoing inventory, replenishing it with a flowing production line. This seems like an obvious way to do things, but it turns out to contradict typical manufacturing practices which try to exploit economies of scale and risk making things no one needed.

Because production is driven by customer orders, and because of heijunka (see below), I saw a variety of cars in numerous configurations come down the same assembly line. The line workers varied their tasks based on which car came past their stations.

Kanban

Each parts box has a kanban ID card, often applied by manufacturer/supplier. When the first part is removed from a box, the worker (consumer) throws the box’s card into a queue for re-order of an identical box. Kanban cards are collected frequently, read by a machine, then trucks arrive filled with a variety of ordered parts to be arranged into the SPS system. Only 20 minutes of incoming parts inventory are kept at the Takoaka plant, continuously restocked through the kanban system.

The cards I saw were plain black and white cards with lots of human-readable numbers plus large bar codes. They identified the parts and where they came from, to restock with an identical box of supplies. The kanban system people are experimenting with for software development meets the literal definition of “visual card,” but has little in common with the kanban I saw at Toyota.

SPS — Set Parts Supply

Parts are grouped with the vehicle they will become part of so assembly workers aren’t running around looking for them. The part grouping area was the only place I saw carts being towed around by people. The rest of the assembly area used robotic carts.

Andon Light Sign — an Information Radiator

Different stations are represented by lights turning green, yellow, or red. Yellow generally indicates a worker is impeded. I frequently saw lights flicker yellow briefly, then back to green as workers caught up. If the light remains yellow, a supervisor goes to the numbered station to help. If worker and supervisor cannot resolve the issue quickly, the station goes red and the line stops.

Jidoka — Intelligent Automation, and Stopping the Line

Sakichi Toyoda saw his mother working on a manual loom, and came up with a semi-automated hand loom in 1890. This progressed to machine-driven looms, which would keep churning out defective fabric even after a thread broke, wasting time and materials unless closely attended.

In 1924, Toyoda-san developed the first example I know of continuous automated testing: The Toyoda Model G automated loom would detect a broken thread, and stop immediately, so defects weren’t produced in the first place. Stopping the line became a fundamental part of the Toyota Production System. Continuous automated testing in the Agile software world is called “continuous integration” — and it’s a key ingredient of successful Scrum.

The Toyota production line can stop either automatically (after a timer runs out on an unresolved yellow) or manually as any worker pulls a cord. I saw this happen at station 4 (out of about 40) for a few minutes. The line stopped! I noticed some people still working even though the conveyor floor stopped advancing the cars. Machines check human work and humans inspect machines’ work, but overall there is greater human involvement in inspection. Every worker is an inspector.

I saw more humans than robots in the assembly area. A lot of human attention is still needed to assemble a Toyota. We weren’t shown stamping, welding, and painting, which use more robots than people. Robots are used for lifting, for repetitive work, and dangerous work.

I also saw many slow-moving robotic carts supplying people with parts, gently following painted lines on the floor like autistic cows.

The “line” is a moving floor assembly line running at constant pace, allowing workers to step on and off, to move with vehicle or not.

Final inspection is much simpler process than I expected for a system with 30,000 parts. The car leaves the factory in a roadworthy state — headlights aimed, wheels aligned, etc.

Kaizen — a Philosophy and Practice of Continuous Improvement

This article will not attempt to cover Kaizen properly, as it’s interwoven into everything Toyota does, and hard to just point to on the factory floor.

Some of the things Toyota does to help facilitate Kaizen are 5 minutes meeting every morning, team meetings, group meetings, and a retrospective 2 hours every month, depending on the group. Most innovations for process and tool improvements come from the shop floor workers themselves, including low tech things like magnets that pick up the next set of bolts from the parts bin each time the worker holsters the socket driver.

In Workplace Management, Taiichi Ohno wrote “The first step in kazien is manual work kaizen. Manual work kaizen is the most important because as a result of manual work kaizen you will learn many things about changes you need to make to your equipment, or changes you need to make to your process as a result of changes you make to your equipment.”

Heijunka — Production Leveling/Smoothing

Toyota contradicts traditional mass production doctrine by reducing lot sizes. Instead of making identical sedans for a month, then retooling for hatchbacks, they make one sedan, one hatchback, etc. right after each other on the same production line. On top of that they vary the configuration from car to car. They mix it up intentionally, smoothing out demand peaks on particular processes.

Ever walk by a construction site and observe that workers were either loafing, or working frantically — sometimes at the same site? When visiting the Toyota plant I was impressed that workers operated at a constant, not frantic, pace. I saw fluid movements, never any jerky movements, running, or other signs of stress. I also didn’t see anyone stationary. I think heijunka contributes to smoothly flowing dance I saw.

By the way, these people work 7 hours 30 minutes per shift. There are three 10 minute breaks (I think) and a 45 minutes lunch break. As I mentioned, assembly worker gets some variety in this inherently repetitious work: different kinds of cars come down assembly line, and assembly workers change stations/roles each break. During breaks, maintenance workers maintain production equipment. Production workers go two shifts. Maintenance groups cover all three shifts.

Should You Try This At Home?

I hope this brief impression of TPS in action has motivated you to learn what people like Jeffrey Liker and Taiichi Ohno himself have written about it.

If you’re a fan of Danube’s work, your business is probably more like new product development than producing thousands of cars that have already been designed. New product development, with its vague requirements and technology risks, still benefits from timeboxed iterations, and not so much by efficiency measures.

Still, I think it’s worth learning why Toyota evolved this approach to manufacturing, and the daunting impediments they overcame.

–mj

Download the PDF version: A Close Up View of the Toyota Production System_blog

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