One critical technique of Lean Manufacturing is to shorten the set-up times between production runs. The cliche term is SMED or Single Minute Exchange of Dies. This technique refers to machine or production line set up activities.
Many production decisions are made with the justification that it is more cost effective to have long production runs because the time lost making set up changes takes time away from production. There is some truth in this logic. Production management courses have various formula to calculate the optimum run or batch size. These formula take into account the length of set up time to prepare the equipment to run the product. The longer the set up time, the larger the batch size must be to amortize the set up time over a larger volume of product. Longer production runs will economically justify the set up time, but they introduce other problems. While you are making one particular product, how do you fulfill customer orders for other products that are not in the current production run? The answer is to make enough product in a production run to cover expected product demand until you can return to that product in your production cycle. This means you have to stock finished goods. Having a stock of finished goods available to fill customer orders means you have to have longer production runs. This can be a vicious cycle.
However, this logic is based on the belief that set up times are fixed and unchangeable. They are usually considered a cost of doing business. But what if you could reduce your set up time? The classic Lean example is the pit crew at a NASCAR race. While it may take you 30 minutes to change a flat tire on your car; a pit crew can change four tires, gas up the car, clean the windshield and give the driver a drink in typically less than 20 seconds. Yes, they have ten mechanics working at once. Yes, this pit crew team practices their drill to shave seconds off their time. The key point is that they can reduce their set up time by a significant amount.
Production set up times can also be reduced from hours to minutes and from minutes to seconds. You can start this set up reduction process by looking closely at what happens in your machine set up activity. Measure the amount of time the operator, or set-up man, is actually at the machine. Look at what has to be completed to get the machine ready for the next product. This close examination can be embarrassing and even painful.
As you begin to take action to reduce the set up time, you will look at tasks as simple as staging tools and dies at the machine while it is still running the current product. With a production schedule, you should know in advance what the next set up will be for this machine. Establish a standard procedure for changing out the machine. Look at a redesign of the product, or the tooling, to allow for faster set up. This idea is actually a lot easier that you would imagine. Train a crew to conduct the set up, instead of using a single man. Use go/no-go gauges to measure the set up tolerances and test parts rather than using special instruments.
By keeping an open mind and remembering that set up times are not fixed but can be reduced, you will achieve major results in the set up time reduction.
Now to reap the rewards of your efforts. Not only will you have more production time available for producing finished goods; you will see a reduction in finished goods inventories; shorter reaction time to fill customer orders and higher profitability. Aren’t these goals worth spending a little time to change a “given set up time”?
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