I recently wrote a guest article with Tom Harada for the Society of Manufacturing Engineers for the May edition of their magazine. Here is a link to the article as printed by SME.

SME Article Link (Click Here)

The first draft of the article was slightly different however including some pictures I took at the Toyota Commemorative Museum of Industry and Technology. Unfortunately the image resolution of the pictures was not good enough to include them in the article. I’ll post the original article below with the images as well.

The Toyota Production System (aka lean manufacturing) has received lots of positive publicity over the past couple of decades in the US and other countries. The recent economic downturn and subsequent decline in company profits may dent some of that enthusiasm, but I suspect the attraction will resume and continue to grow in the future.

Despite many attempts at implementation, few companies have been able to match Toyota’s success. This unsatisfactory situation is partly explained by the inherent difficulty of driving improvement. No one ever claimed implementing lean was easy. Also, however, we believe there is a lack of appreciation for the emphasis Toyota puts upon development and improvement of manufacturing processes in primary metal shops, such as casting, forging, machining, stamping, and welding.

Most early characterizations of TPS played up the material-flow aspect of the system. For example, as early as the mid-1970’s, Toyota’s prowess in manufacturing was being attributed to its famed “kanban” system. This view of things was severely limited, because in reality a kanban is nothing more than a simple tool used to control parts of Toyota’s Just-In-Time system, and Just-In-Time is merely one component of the company’s manufacturing system.

Later examinations of the TPS played up the system’s kaizen aspect, and the importance of conducting improvement workshops. Some companies went so far as to establish quotas for the number of workshops that needed to be conducted to “become lean”. Typically these workshops focused upon standardizing work practices, time and motion study, rearranging work flow, reducing the number of operators, shortening setup time, and attempting some form of one-piece flow. Many of these techniques have old roots in Industrial Engineering.

More recent characterizations of TPS have centered on the notion of a value stream, process flow, employee development and, of course, waste elimination. There is nothing wrong with these concepts or the techniques mentioned above. Unfortunately, as many practitioners are finding, on their own these concepts are often not sufficient to improve quality, cost, and delivery, especially in machine-intensive operations.

Our combined experience suggests that TPS is much like the old 3-D mechanical Rubik’s cube puzzle, which is not easy to sort out. Just looking at the cube from one angle will lead to frustration and inability to solve the puzzle. Portraying TPS as a material flow system, or even a system of human development, is necessary but not sufficient to consistently drive improvement. There are other dimensions that often must be emphasized. One of those dimensions is much more mechanical and machine-based in nature.

It’s worth noting that TPS initially evolved in Toyota’s engine plant in the 1950’s and 1960’s under the direction of Taiichi Ono, and not in the final assembly shops. Most textbooks use assembly-type examples (U-shaped cells, standardized work, parts organization) to depict TPS. Engine plants, however, depend upon machine tools, precision measuring equipment, jigs, fixtures, and tooling to remove material and make precision components such as crankshafts, cylinder blocks, or pistons.

Toyota’s productivity level was estimated at 1/9^th that of Ford Motor Co. when it began making improvements in the 1950’s. Improvement required a long battle-initially fought in Toyota’s machine shops–to catch up to North America in terms of quality, cost, and productivity. A trip to the Toyota Commemorative Museum of Science and Technology in Nagoya depicts the journey undertaken by Toyota since the inception of the company.

Nowhere in this museum will you find some of the more common and hyped tools of TPS that are touted in the US or other countries. Instead, this museum focuses on the importance of “making things” the “Spirit of Being Studious and Creative”, and the importance of production technology. We believe the actual improvement journey that Toyota embarked on in its engine plants and other machine-intensive shops is grossly under appreciated, and an that failure to understand what Toyota accomplished on the floor is one of the reasons companies often struggle to achieve gains in similar shops.

Some explanation may help illustrate this point. Occasionally we visit companies implementing TPS in machine-intensive shops, and are asked to give feedback about ongoing improvement projects. Usually the ongoing efforts focus on material flow in a value stream, scheduling, 5S, standardized work, or visual control. Sometimes a TPM or setup reduction workshop is underway. The problem is that machines continue to run with availability in the 50 – 80% range, quality varies widely, and scrap is common. Equipment-related delays are frequent as well. Operators are usually dismayed by the lack of connection between the problems they face on a daily basis, and the ongoing improvement efforts driven from above or by a corporate staff.

We’ll be blunt to make a point – Machine-intensive shops practicing this flavor of lean activities are more likely to struggle than succeed. Assume one company takes 10 processing steps to make a widget, and has 5% scrap, 70% uptime, rework, and other delays, and runs a fair amount of overtime. Another company has seven processing steps, near-100% availability, and 0.05% scrap and rework. Assume that labor, overhead, and material costs are roughly the same. Which one is in better shape? Which one would you rather manage?

The latter case is the easy choice. Toyota’s success in machine-intensive shops such as casting, forging, machining, body weld, and stamping has a lot to do with the physics of metal removal and mechanical process improvement.

The first precision machine tools in Toyota shops were imported from the US or Germany, and were not of Japanese origin. Basically, all of these machines were operated on the one-man, one-machine basis that was normal for the time. Below is an image of an old engine lathe restored and located in the company museum. Taiichi Ono, the company’s manager of machining, embarked upon a strategy of breaking down this one man one machine norm by having one operator run two machines, then three, and then four.

This methodology was highly effective, and helped Toyota close its productivity gap versus the US. Eventually, however, the effort ran into a wall. One person can only cover so many machines before you run into cycle-time barriers, quality problems, and minor stops between processes. In the 1960’s, Toyota put great effort into purchasing and building transfer lines as a way to improve capital productivity. Some of the initial machines are still on display at Toyota’s Commemorative Museum of Science and Technology. The plaques on this display, and others around it, proudly note the incremental advances Toyota made in building machine tools, jigs, fixtures, tooling, and measuring devices that drove capital productivity. This capital productivity can’t be achieved merely by the superficial efforts we have outlined before–i.e. one-piece-flow, pull systems, kanban, 5S, and other lean techniques. It requires hard-won mechanical prowess at the process-technology level.

Look below at the image of a machining line that is no longer in existence at Toyota. It was replaced by a more modern and efficient layout about 10 years ago. Toyota is picky about allowing pictures of current facilities, so this one will have to suffice. In this layout for a crankshaft line, a single operator can run dozens of automated processes. More specifically, the line is all automated. The operator’s job is to conduct periodic quality checks to audit the automatic ones, change cutting tools on a counter-based interval, conduct minor troubleshooting or preventive maintenance, and alert supervisors to problems requiring the help of either maintenance or engineering. The line ran at near 100% uptime and 100% quality.

How did Toyota arrive at this super-efficient machining system? Probably not the way you might think or might have read about in textbooks. This manufacturing line, and the one that replaced it, were based upon years of hard work in the areas of material removal, tooling, and machine and fixture design, as well as controls engineering. Toyota employs several hundred process experts worldwide who constantly gather data on the performance of current equipment, and work to build a better process in the future. Visitors to Toyota take the reliable and capable machines that they see for granted. However, such reliability and capability are the bedrock of the Toyota Production System. As an experiment, try running a pull system that involves standardized work with high levels of downtime or uneven quality. Unfortunately, it won’t function very well.

Why does such process technology and capability go unnoticed by most observers of the Toyota Way or the Toyota Production System? We can offer up several educated guesses. For starters, consider the analogy of the iceberg and the ocean. The items above the surface in a Toyota factory are what you will notice during initial visits. Material flow, kanban, visual control, and standardized work, for example, are easy to spot.

Secondly, it’s difficult to show the inner workings of a complicated production process. Toyota makes high-quality grinding machines at an affiliated company known as Toyoda Machine Works. These machines removal metal, and are controlled to the level of a few microns of dimensional accuracy. One of the keys to this abrasive-machining process is its patented hydro-stat main spindle bearing. The bearing is impossible to show, because it’s inside the machine, and hard to explain to people not familiar with the basics of the process. So this type of feature deep inside the process goes unobserved by most visitors to Toyota.

Third, the details of the manufacturing process involve technical standards, as well as drawings and blueprints with specifications and tolerances. This type of detailed information is considered confidential by Toyota-and all other manufacturing companies. There is no incentive to show this aspect of TPS to the outside world. You can visit Toyota and get a copy of the standardized work chart with ease, but forget about obtaining any information that pertains to tooling, machine design, or fixtures. Toyota knows what is critical to their system and important to protect.

We suggest that persons looking to make improvements in machine-intensive shops not worry too much about the descriptions of TPS or lean manufacturing one sees in textbooks. Instead, consider your own problems and needs. Productivity and quality in machine shops heavily involve material quality, process capability, and technology. Like the Rubik’s cube analogy we referred to in the beginning there is no set answer that can tell you where to begin. The right move depends upon where you are in terms of capability and availability.

In general, we can make some comments and ask some questions that might help define a good starting point:

• In machine-intensive environments, make sure you can make the part right the first time. Jidoka (Build-in Quality) is not a pillar on par with the Just-In-Time part of the Toyota system by coincidence. The Jidoka slogan (1902) is older in TPS than the Just-in-Time slogan (1937), and just as important.

• The key to improving quality is often found in raw materials from suppliers. No pull systems and no amount of time spent standardizing the work routines of operators will solve supplier-quality problems.

• Internal in-process quality is usually affected by the quality of tools, jigs, fixtures, and critical parts of the machine. Toyota worries about maintaining 5 microns of runout (or less) in spindle heads on machine tools, for example. You probably have some critical factor in every process that deserves equal attention.

• Mechanical downtime must be analyzed and studied if it’s to be reduced or eliminated. Root causes for all types of downtime have to be pursued with the same level of rigor that is used in quality control, if you expect to improve.

• Machine cycle times can and should be studied for improvement when need. Decreasing the amount of stock removal (tighter tolerances from suppliers) is often effective providing quality can be maintained.

• Efficiency (simply making parts per hour) should not be allowed to drive you to overproduce. Machines must be governed by the over-arching need to not overproduce and just build inventory.

• The operator interface with machines needs to be carefully considered. Don’t make employees merely monitor machines. Have machines alert people when there is a problem and then initiate the problem solving process.

• Taiichi Ono opined that success in TPS requires application of the scientific method. Learn to sort out “effects” from “causes” and problem-solve machine-related issues. This skill will take you further than anything else that you will ever read about TPS.