Shigeo Shingo said, “We have to grasp not only the Know-How, but also the Know-Why if we want to master the Toyota Production Syst.”
This means that before anything else, we need to understand why the Toyota Production System (TPS) was developed and why each of the basic elements are important to grasping the know-why.
What are the origins of the Toyota Production System?
Ohno Taiichi was a Japanese industrial engineer who is widely recognized as the father of TPS, which inspired lean manufacturing in the United States. In “Toyota Production System,” by Taiichi Ohno, he explains the origins of TPS. Toyota’s goal at the time was to “catch up with America in 3 years” because the American automobile industry was said to be 10 times more productive than the Japanese.
Understanding that American workers simply couldn’t be exerting 10 times the physical effort of Japanese workers, they concluded that the Japanese must be wasting something elsewhere. If this unknown waste could be eliminated, then productivity would increase by a factor of 10. According to Ohno, “This idea marked the start of the present Toyota Production System.”
The basic elements of the Toyota Production System for lean manufacturing
While this list is not comprehensive, it’s a good start to understand how the following elements fit together.
The critical eye: In a previous blog, I discussed the need to develop a critical eye to see waste in manufacturing. This is done by carefully implementing the various elements, measuring the impact, and reflecting on the results and what is learned.
Standardized work: We should explore the technical tool of standardized work. When standardized work is implemented, it begins with calculating the required pace of production, or the takt time. Calculating takt time requires knowing the leveled demand over a period of time and the available production time in a given time frame.
Level demand: When determining level demand, the demand over a period of time is divided by the number of production days in that same time period. For example, expected demand for a month may be 1000 units with twenty production days. The daily output target is 1000 divided by 20 which equals 50 units per day.
Takt time: Available time per day is determined by subtracting breaks, lunch, standard meetings (i.e. daily shift start or end meeting) from the number of minutes in a standard shift. For example, an 8-hour shift is 480 minutes. Subtracting two 10-minute breaks, a 20-minute paid lunch, and 5-minute start of shift meeting leaves 435 minutes of available production time. Takt time is then 435 minutes divided by 50 units, or 8.7 minutes.
There’s no allowance for unplanned breaks, downtime, production losses, etc. There’s also no allowance on the demand side of the calculation- perfection is the goal! In creating standardized work, the total work content is divided by takt time to determine the number of people required and each but the last operator is given an amount of work as close to takt time as possible. Again, perfection is the goal.
Unfortunately, an expectation of perfection will result in not meeting customer demand. Something must be done to close the gap between perfection and reality. Lean manufacturing exposes the wastes in any process by creating an environment where perfection is expected and all problems are exposed to be solved. Tools like andon (expectation that team members stop the line when there is a problem), standardized management methods (prevent, react to, and solve problems), resources (people) that respond when problems arise are just a few of the things that must be put in place in a lean manufacturing environment.
The key challenge with exposing and eliminating problems
In a good lean manufacturing environment, the structure must be put in place to respond to and eliminate problems. The improvements from implementing lean manufacturing are dependent on the continued work in this area. Most of the aspects of lean manufacturing are intended to either expose or eliminate problems.
Conversely, a traditional manufacturing environment seeks to hide problems by adding resources. For example, how do traditional operations respond when customer demand is not being met? Resources like more equipment, people, shifts, inventory, and automation are added to the operation to cover up the existing problems. This is even more evident today as companies struggle to hire and retain qualified employees. Unfortunately, this just multiplies the waste that already exists by adding resources that perform at a similar or reduced level of performance.
The challenge for anyone attempting to implement lean manufacturing is to understand that problems will be exposed and must be solved quickly. The key challenge is to not expose so many problems at one time that customers and employees are negatively affected.
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