The Business System
In Japan most heavy, hazardous, and complex maintenance is done by contractors. The individual plants usually don’t have a deep or large maintenance department, except for a few mission critical services.
Of course, one big reason TPS thrived was that it was supported from the top of the organization. TPS permeated all activities of Toyota. It was patiently nurtured, revised, and improved until it entered the company’s DNA and it was expressed in most decisions made in the plant.
For these reasons, TPS was a logical system that was adopted and supported over a long period of time by Toyota’s management.
TPM, TQM (total quality management), Lean manufacturing, Lean maintenance, and JIT form the basis of the Toyota Production System (TPS). All of the programs dovetail together and support each other. In the end, the company produces high quality products with as few inputs as possible and as little waste as possible. For more information on this fascinating story, consult The Machine that Changed the World (bibliography).
The TPS House Graphic
“One of the most recognizable symbols in modern manufacturing is the ‘TPS House’ diagram as shown below. The diagram (Exhibit 1-3) is a simple representation of the Toyota Production System (TPS) that Toyota developed to teach their supply base the principles of the TPS. The foundation of the house represents operational stability and has several components, one of which is Total Productive Maintenance.” From an article by David McBride at the Reliable Plant web site (for the complete article, go to: http://www.reliableplant.com/Article.aspx?articleid=8417).
Exhibit 1-3 The TPM House
The house graphic shows the relationship between all the parts that make up TPS. It also shows TPM to be a foundation activity necessary for success. The results are the roof which when achieved becomes a competitor killer!
The Toyota system is designed to remove waste from the production of automobiles. It is interesting that the Japanese words become like Zen koans (stories) that disciples study to understand the mysteries. In this case, the Japanese words identify a type of waste. For example one type of waste is overburden and the Japanese word is muri. The waste associated with doing things differently each time (inconsistency) is called Mura.
All types of waste are called Muda. The challenge is designing a process capable of delivering the required results smoothly; by designing out “mura” (inconsistency). The design ensures that the process is as flexible as necessary without having to overproduce “muri” (too much work-in-process or overburden) since this generates “muda” (waste). There are seven kinds of muda that are addressed in the TPS:
1. overproduction
2. motion (of operator or machine)
3. waiting (of operator or machine)
4. conveyance
5. processing itself
6. inventory (raw material)
7. correction (rework and scrap)
The elimination of muda has come to dominate the thinking of many when they look at the effects of the TPS because it is the most familiar of the three to implement.
The entire organization is aligned to solve the most pressing problems that get in the way of high quality/ high quantity output. TPS has several sub-programs (of which TPM is one).
JIT
JIT is an advanced method of regulating production. Using JIT, only a small number of parts are made at one time. In some cases, it might be enough parts for 4 or 8 hours of assembly line production. These parts are replenished on a just-in-time basis. That means when the last part is assembled onto the product, a pallet of the next batch of parts is put down. The overriding issue is that when the machine is needed, it had better work or the line will be shutdown in a short time (like 4 or 8 hours). High reliability and quick repair are essential elements of a JIT environment.
When Harley Davidson, the leading American motorcycle maker, became an independent company, its management decided that JIT manufacturing was the best solution to the quality problems they were experiencing at the time. The thought was with minimal part runs a quality fix would get onto motorcycles within days. They used to run months of parts at a time to optimize and amortize the set-up time. Under the old plan, it might be months before the parts and subassemblies in stock were used up and the improved part appeared in bikes.
Motorcycles were assembled in York, PA, and the engines and transmissions were made and assembled in Milwaukee, WI. The truck of engine and transmission assemblies was supposed to arrive when the York plant got down to a shift of stock. In other words, if the truck delivering the engines was more than 8 hours late, the York assembly line would have to shut down.
Now imagine running JIT with equipment that was only 70% reliable. Three times out of 10 the equipment would be down when you needed it to produce parts.
“Total productive maintenance (TPM) is indispensable to sustain just-in-time operations,” says Dr. Tokutaro Suzuki, Senior Executive Vice President of the Japan Institute of Plant Maintenance in TPM in Process Industries. In a JIT system, he emphasizes, “You have to have trouble-free equipment.” Prior to the adoption of TPM, Japanese manufacturers found it necessary to carry extra work in progress (WIP) inventory “so that the entire line didn’t have to stop whenever equipment trouble occurred. The concept is that the operator must protect his own equipment,” he explains. “Thus the operator must acquire maintenance skills.”
However, maintenance experts may still make periodic inspections and handle major repairs. Design engineers also play a big role. They must take maintenance requirements — and the cost of equipment failure — into consideration when they design the equipment, stresses Dr. Suzuki.
Another Japanese Vocabulary Lesson
Using the Japanese language, TPM focuses the energy of the organization on the actual piece of work (gemba), the actual part (genbutsu) being made, and the actual activity performed or as the Japanese translation says phenomenon (gensho).
TPM directly attacks the sources of ineffectiveness by concentrating on all the sources of loss of production (not only on the maintenance-related losses). This is important because most mistaken impressions think the focus of TPM is on maintenance whereas the true focus is on high quality output.
Where Does Efficiency Fit In?
Most companies spend enormous amounts of money on improvements in efficiency. Efficiency is defined as doing things the right way. Industrial engineers spend a great deal of effort on insuring wasted movements are eliminated from the production process. TPM can be said to take the next step. TPM looks at doing the right things right. By attacking all of the losses, TPM insures that at the end of the day, the pile of saleable parts made by the process is bigger. In some cases, after TPM, the pile of good parts is a great deal bigger.
Where did the idea for TPM come from in your plant? As mentioned, if the maintenance department initiated the program, look out. It is difficult to convince anyone that the program is not just a way to off-load maintenance work onto operations. Related to this question is another: Who is driving the effort?
What difference does your situation make to the success of TPM? If your machines are large or hazardous, or they require enormous skill to even consider fixing, then traditional approaches to TPM will not easily work. The fundamental shift is not maintenance activity to operations (which everyone seems to focus upon)