If I had five dollars for every question I ever had to answer about Standardized Work or Standards inside of Toyota I’d be a very wealthy and retired individual! Seemingly this topic and associated themes pertaining to standards should be easy but that is not the case in reality. There is more than meets the eye with this topic and that is what I suspect is lurking behind the scenes with this question. I will explain some of the types and forms of standards inside of manufacturing at Toyota involving how they work and how they are changed.
As is normally the case I am going to explain things from the perspective of previously working in Toyota’s historic Kamigo Engine Plant in Japan. This site and its predecessor at Honsha Plant are where Taiichi Ohno practiced and perfected his system for improvement. There are derivative and alternate forms of what I will explain but I will stick to the orthodox version for simplicity and clarity.
One important definition of “standard” in a typical dictionary is as a “basis for comparison”. In the sense of improvement or Kaizen this is very important. With no measured improvement between two cases (think before and after a change for simplicity) there is no Kaizen. Continuous change alone does not equal continuous improvement. Similarly as the Nobel prize winning British physicist William Thomson once said, “If you can not measure it, you can not improve it”.
There are levels of standards and documents inside of Toyota just like in any company. There are governing bodies of standards and regulations inside the company known as Toyota Motor Regulations (TMR) and Toyota Manufacturing Standards (TMS). Both sets together are about the size of 20 encyclopedia volumes and considered highly confidential and proprietary. When I started with the company in the 1980’s they were still mostly in Japanese and not very often changed (think application of bearings, etc. where the laws of physics are pretty constant or electrical power coming into the plant).
Very rarely would anyone outside the company (if ever) see or need to see these documents. So I will begin a level up from this line of demarcation. In most sites at Toyota when you view documentation on the shop floor (and hence stuff we might change from time to time) there are four basic categories that material falls into. The first group we referred to as work standards, the second as job breakdown sheets, the as third standardized work charts, and the fourth various forms or documents used in Kaizen activities. Each category is different, used differently for different purposes and subject to different rules and approval routes for changes. I will attempt to explain a little about each one.
Work standards is the literal translation of the term (作業標準 / Sagyou Hyoujun) in Japanese. It is best to think of these documents as the building blocks of a production process inside of Toyota. Some are created internally by engineering departments (process engineering, tooling, quality, etc.) and some are created by companies who supplied our manufacturing processes. I worked in an engine shop so we had a lot of machine tools. The most important work standards for us were the operation drawings (what material removal in what manner was specified clearly for each step in the process), the tooling layout drawing (what exact tooling conditions we used to qualify and start up the process), and the quality check drawings (what check, what method, what gauge, what frequency, etc.).
I could rattle off easily a dozen or so import work standards we used on a daily basis inside of Toyota when required. A typical machine tool in Toyota would probably have about a dozen or so work standards associated with it when you consider the machine, process, tooling, hydraulics, controls, etc. These were invaluable tools used in problem solving inside of Toyota for difficult problem solving cases. When simple observation did not suffice systematically we’d go through the work standards, one by one, to verify that nothing had changed from the original condition.
Changing of a work standard was done very infrequently and normally an engineering activity for the types of items I just described. Maybe we wanted to improve the life of a tool, or alter how the part was clamped in response to a problem on the shop floor, etc. Problems or kaizen sometimes drove us to reconsider work standards but by and large these did not and should not change very often if we planned and launched the process correctly. Toyota considers these documents confidential. As a result people on a tour of the company rarely see them and Toyota is happy to not really explain them to anyone anyway. I have never run across anything so thorough however in any other company as Toyota’s work standards.
The second category of documents on a shop floor inside of Toyota is that of Job Breakdown Sheets (作業分解シート). These documents pertain to training on the shop floor and are created when needed for training purposes. Typical triggers are during new launches, cross training, new processes arrive on the shop floor, quality problems arise or some other event occurs. The documents are created by team leaders or lead people on the shop floor and are comprised of major steps, key points, and reasons why we do it this way. There is a lot more to training than this job breakdown sheet but it is a key ingredient to the training process. At least it was historically. Today it usage is declining for a variety of reasons.
The important thing to note about Job Breakdown Sheets is that they contain Key Points, and Reasons Why for important steps in the process. Those key points and reasons why have to come from somewhere and that somewhere is usually a work standard which I have outlined above. Work standards don’t change very often. Job Breakdown Sheets change a little more often. The reason is that training depends upon the skill level of the trainer and the level of the trainee. The Job Breakdown Sheet and the Job Instruction Training process is essentially a standard and a standard way of training. The standard (i.e. the Job Breakdown Sheet) changes as needed based upon the call of the person conducting the training. The sheet is technically a set of notes for the trainer to prepare and execute from and not just for the trainee to merely read. So these “standards” change somewhat as needed but still not all that often once they are drafted.
The third and most famous category of shop floor documents inside of Toyota is that of Standardized Work (標準作業 / Hyoujun Sagyou). Most visitors mistakenly assume this set of documents encompasses everything inside of manufacturing at Toyota but it does not. True Standardized Work has to meet some strict preconditions and meet three important elements to be considered true standardized work. It is far more than a work instruction and involves time studying the elements of the job. That explanation alone is a whole question onto itself and best left to another time. However the important thing about Standardized Work is that it is expected to change fairly often. In Toyota Japan this was often done monthly. The reason why is that Toyota in Japan historically changed line rates (takt time) monthly which set off a corresponding change to standardized work on the shop floor. As the line speed changed the production operator might have more or less work to do any given month (takt time was one of the three elements of Standardized Work I referred to up above). As a result we’d need ideas about how to allocate and lay out the work content differently almost every month in production.
In advance of the change in takt time the supervisors would be doing some pre-work and start to figure out the new work allocation on their own. However the best ones also were able to involve their work teams in the process and solicit ideas along the way. There were formal mechanisms for doing this (suggestion sheets) as well as informal ones like discussion during breaks, work team meetings, or over lunch, etc. Production employees were a key ingredient in making changes to standardized work on the shop floor. Most standardized work changes could be made with little approval from engineering or upper management. Standardized Work items that directly impacted safely, quality, or ease, etc. were of course evaluated more carefully.
The final category of documents on the shop floor that involved standards and change were generically known as Kaizen (改善) documents. There were a wide variety of formal and informal tools used for analytic purposes inside of Toyota. Time study sheets, motion study symbols, flow charts, work combination charts, and other items etc. were all used on the fly as needed to generate improvement. Kaizen is really a process of course and not a document so this fourth heading is a little different from the previous three I mentioned.
However there was no ducking Kaizen inside of Toyota. Toyota annually expected anywhere from 5-8% improvement in most operations so some form of improvement was always on-going. Cost, quality, safety, etc. you name it. Toyota welcomed input from all employees regarding the attainment of goals. The best leaders were often the ones most adept at pulling specific improvement ideas from their work teams. That of course takes some time and development before it occurs on a regular basis. However it is the grease that lubricates Toyota’s improvement process.
So to answer in summary there is no single or easy answer to the question. Some work standards never changed while I was at Toyota (voltage into the plant, pressure on a hydro-stat bearing inside the machine) and there was no good reason to change them. Neither individuals nor teams would change them. Other items like the contents of training would change as needed by the person conducting the training. Standardized Work in an ideal case changed monthly and good leaders pulled improvement ideas out from the production team via a structured process. Kaizen activity was occurring somewhere constantly and usually involved methods the work team has some ability to change (time, motion, quality, ease, work simplification, etc.). Technical standards could not be improved without the approval of engineering and had a more thorough approval process. Ideas regardless in the end tend to come from individuals (they don’t occur simultaneously to everyone on a team) and then are modified either in discussion, review, trial, or debate.
In Job Relations training (which has nothing to do with standards oddly) inside of Toyota there is an important point of emphasis for the leader. When there is conflict of some kind the supervisor often has to make a decision which is not going to be popular with everyone. They are coached to think what is best for the production situation, what is best for the team, and what is best for the individual. From my experiences that is generally the order and thought process that was adhered to in most cases.