So what are we looking for out there? Do we have a process for recognizing waste?
Within the Toyota Production System, Taiichi Ohno put waste into Seven different categories:
- Over Production
- Over Processing
Over Production happens when "Just in time" to the customer isn't followed. It allows you to produce, because you can, at a rate that is normally faster than customer demand. These products are then "stockpiled" for a "rainy" day or whatever reason to meet the need at any given time. This waste normally "hides" or "masks" problems since there are plenty of parts stored in any empty space found (Sometimes even warehouses). This is one of the worst waste categories there are because it leads to excess Inventory (another waste) which leads to increasing costs for the company and customer. Other aspects companies do not think about is the Quality control processes with Over Production, it is very hard to control versus a first in first out process.
Waiting takes place when an operator may have idle time when waiting on machines, parts, or production. If fluctuations happen in production volumes, waiting can be seen as more than process related. Entire lines can be effected by Over production, and part shortages can create a snowball effect to others in the process. As you will see these 7 Wastes are all interrelated.
Conveyance is necessary to many production areas in the form of "water-spiders" or production control logistics due to the nature of transferring parts from place to place. Many consider Conveyance itself to be muda or waste. What companies must look at is "how" we transport product or materials and are we doing it the most effective/efficient way. It's important to look at the shortest routes, maximizing space on the truck, the Heijunka (part leveling) of parts taken (highest demand to lowest) and contain sizes. These are just a few ways to look at waste in conveyance.
Over Processing is the one most often confused with Over Production. What is the difference you may ask? Over-processing is happening within a process at the Gemba (work-site)....it can be equipment, resources or people related. For example, if a machine/mold is responsible for cutting out the sunroof opening on the Roof Headliner wouldn't you want that machine to do it in the most efficient and effective way possible. One of the lessons the Japanese taught me was to look for unnecessary motion in equipment. In this case was the machine traveling open too far creating extra time for the cycle time? If the machine time could be cut by 10 seconds it can prevent team members waiting on the machine and add more value to the process instead. These are the types of Over processing wastes we were taught to look for in regard to equipment. Its a very common waste most overlook.
Inventory is related to Over production. Its a very costly waste to the company in regard to excess space, storage and quality control methods. Again it happens when "just in time" isn't being followed to customer demand or takt time. This can be in the form of raw materials, work in process, and finished parts.
Motion is one of my favorites to look for at the GEMBA. These are motions within the process that do NOT add value to the customer or product. These can be see as excess walk time, simple actions of picking up a hand full of screws and orientating them in your hand correctly, reaching too far or in unacceptable ergonomic positions, repetitive actions not being streamlined, and many others in regard to an operators path in completing their work or parts orientation. Sometimes motion can be interrelated to the Heijunka of parts coming down the line, if a flow rack isn't correctly stocked depending upon the part leveling then a lot of wasted motion can occur in unnecessary trips or steps to the flow rack. It's another common waste that is accepted as the "norm" at the GEMBA.
Correction means we do not get it right the first time. It's when we must recreate a product or part because of a quality issue or discrepancy within the process. It can also be in the form of inspection. If a operator doesn't build in Jidoka the first time, re-inspection may need to occur and this is considered a waste in time and manpower. If scrap or rework is high in your company then a daily go and see should be happening to determine current situation.
I hope this has helped to explain the Seven Wastes as described by Taichii Ohno.... if focused upon can change the way you look at your processes therefore adding value to the customer.
Until next time