Lean Tools: Just-In-Time (JIT)

Every one of our activities in life could be called a process. From simple tasks like bathing and eating to complex tasks like designing and building rockets, the things we do are usually “work in progress” (WIP). When we examine our activities as processes—especially in the context of work—we usually want them to be efficient, reliable, safe, low-cost, and done at the right time.

The speed of a process is usually measured in cycle time, which is the total time required to produce a product or service from start to finish. Therefore, cycle time reduction can improve costs for our customers and us. That’s the broader goal for right now—reducing the length of cycle times.

One technique that can shorten cycle time is Just-in-Time or JIT practices. When you provide materials, services, or people just before they are needed, right where they are needed, and in the proper arrangement and orientation, there is a minimum of waste in the process. When examining these processes, note that work in progress (WIP) in the form of raw materials or partially-completed work should be kept to a minimum between processes and at the starting point of processes. If providing this WIP is included in the process cycle time, as it probably should be, providing excessive WIP or providing it before it is needed ultimately just extends the process cycle time.

When management accepts JIT as a method of doing all business and begins to implement it, most people fear the possibility of frequent, small-size deliveries. They are afraid they will run out of work to do and be delayed in their production. A comprehensive JIT system takes into account that schedules for manpower, materials, and machines must be balanced to meet customer needs, both when they need it and at the quality required. These requirements are for internal as well as external customers.

The Single Piece Flow technique allows us to only make the quantity needed to fill the hole or to be “pulled” by the next operation downstream from their operation. This keeps the WIP to a minimum and is usually managed with a good Kanban system. More on these down the road.

Before you start to implement brand-new JIT techniques or change any floor layouts, you should study the current process thoroughly and document it with a flow chart or Value Stream Map. A few other things to remember as you start JIT:

  • Remember that employee training in the necessary processes and procedures will be vital to your success.
  • Don’t underestimate the possible cost of these changes. They may be costly.
  • Tools and equipment need to be flexible and available to the people who use them. Avoid building any new walls or barriers that impede the flow of work.
  • The implementation team should be interdepartmental and from all levels of the organization. It needs to work on everyone’s level.
  • The implementation team will need to be creative and not be afraid to make mistakes. This is sometimes a tricky change to make.

Teams may come up with ideas for bells, whistles, or lights to be signals for replenishment of materials just-in-time. It is suggested to make temporary devices as signals and let the workers within the process area try them and modify them to meet their needs (and the needs of the production schedule). This trial-and-error method helps to build buy-in from all concerned parties and often generates additional ideas that engineering or management personnel might not have had. Worker involvement in setting up the JIT system in their work area or zone is critical because they’ll have good direct input, seeing as their work zones are where they will spend the most time.

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