What could be better than being just in time for somewhere you were scheduled to be or a task you had to do? That is to say, you were not too early on arrival, wasting valuable time standing around doing nothing. Nor were you too late to the task, not being able to complete on schedule that which you were asked to do. In short, wouldn't it be the best case scenario for you to produce the right task at precisely the right time to maximize both your time and productivity? This notion is the concept behind the philosophy of lean manufacturing referred to as "just-in-time", or JIT production.

In JIT production, we are seeking to eliminate costs that add no value to the final product. It is certain that without critical thought applied to a manufacturing system as a whole, the potential for waste in process is heightened. These forms of waste can include the accumulation of excess inventory, faulty production methods resulting in scrap, and even the unnecessary moving of materials and specific labor actions (or inactions). In essence, JIT is most associated with repetitive manufacturing processes that result in the same products being produced on a routine basis. It is designed to drive inventory buffers to zero and achieve a lot size of one; this to reduce costs through the long-term maintenance of material and/or inventories.

One of the primary goals of JIT is to stabilize uniform plant loading in such a way that there is a constant daily production and a stable production schedule that allows the use of backflushing to manage inventory (i.e., automatic accounting of material consumed for production as confirmed by BOM's upon completion). These are particularly important considerations when scheduling for mixed mode assembly where you desire to repeat sequences in order to produce the same mix of products on the same production line each and every day.

Another desired outcome of JIT is the significant reduction of set up times. By cutting down or even eliminating set up time in the factory, you will improve your bottom line through an efficiency gain of more time spent in other plant areas needing improvement. A nice mark to shoot for is set up times of less than 10 minutes through better planning, coordinated process design and development, and even the redesign of the product itself. An added benefit of set up time reduction is an equal reduction or elimination of the inventory needed to cover machine changeover time.

Through JIT production, there will also be a better consistency of scheduling and, hopefully, reduced direct labor costs. When jobs are not in the production cue, labor forces can be reduced or reassigned to other plant tasks that may not be as routinely undertaken-to improve their performance in the overall inventory cycle system. As well, work forces should be trained to be more flexible in the operation of several shop floor machines and the maintenance of the equipment. In other words, JIT mandates that employees see themselves as empowered by their management to have more responsibility for their work and for the general productivity of the company.

Though there are several other goals and benefits in the JIT approach to manufacturing, and a few problems with it, it is enough to say for now that JIT is necessary to maximize the desirable efficiencies of pull-production. When you are able to pull parts to production stages only when they are absolutely ready to be used, inventory flow is improved, goods are processed faster, and bottom lines are enhanced through reduced lead times and lot sizes. In other words, waste is reduced while on-time delivery is enhanced. And, waste reduction in manufacturing is, as we all know, a good thing.