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Constraint Management
Manufacturing managers frequently look for tools and methods to help them identify actions requiring immediate attention. In this way, they can help ensure production output matches Customer demand. This is where OpenMFG’s Buffer Management system comes in. Buffer Management is used to evaluate Items, Work Orders, Purchase Orders, and Work Centers—and then prioritize each, identifying which should be worked on and/or addressed first.
Buffer Management
What is a buffer? In short, a buffer is a little extra of something that we maintain to ensure we can handle unexpected fluctuations. OpenMFG’s Buffer Management system reports on three types of buffers: stock, time, and capacity. The following examples from daily life may help explain the three different kinds of buffers:
Stock Buffer: A stock buffer is like the extra coffee we keep in the cupboard to make certain we have enough should company drop in. For example, let’s say we want to always keep at least three pounds of coffee on hand. Three pounds, then, is our buffer quantity. As long as we have this buffer, we’re confident we’ll have enough to serve unexpected guests. Whenever our supply drops below three pounds, we’ll put coffee on our shopping list and buy more. Just because the coffee falls below three pounds doesn’t mean we’re in a critical situation. However, if we fall significantly below that level, we need to act immediately.
The critical buffer status in the OpenMFG Buffer Management system is 66%. In other words, any time we consume 66% of a buffer, then it’s time to act immediately to resolve the situation. Using the coffee example, if our supply drops to one pound (and our buffer quantity is three pounds), then we’ve used up two-thirds of our buffer--or 66%. With that much of our buffer consumed, we need to buy more coffee right away. The 66% value is a percentage that is widely used in academic research and practical real-world implementations of the Theory of Constraints--a theory pioneered by Eliyahu Goldratt.
Time Buffer: A time buffer is like the time we factor into a trip to the airport to catch a flight. Let's say we allow ourselves three hours to reach the airport, check bags, pass through security and proceed to the gate ready to board. That means our time buffer is three hours. If we get stuck in traffic for two hours, then we've used up 66% of our buffer. This is now a critical situation requiring our full attention. We must act immediately to either get out of traffic, take an alternate route, or reschedule our flight.
Capacity Buffer: A capacity buffer is like the surface on your barbecue grill which can hold up to 12 hamburgers at one time. In this scenario, the grill’s capacity buffer is 12. If each hamburger takes 15 minutes to cook—and you can cook 12 at a time—then you can produce 48 hamburgers in an hour. Now, let’s say you’ve got 100 guests coming for dinner. If your plan is to feed everyone in one hour, you’ve got a capacity problem. You’ll either need to fire up an extra grill, or start cooking an hour early to build up your stock burger buffer ahead of time.