A series production recipe – do not use MRP!

Have you ever asked yourself, how your production planning methods would work out in your private kitchen? If something works out for your company, it surely will master truly lean processes at home, right? Sometimes a thought experiment like this reveals the weak spots of daily practice within a company. So let us take Material Requirements Planning (MRP), which is a commonly used planning concept in series production, and try to cook a meal.

Successive cooking with MRP

Imagine you want to invite a group of four to dinner on the weekend. You look up one of your favorite recipes and start cooking – assuming that you have all your ingredients in stock, since you cook this particular meal quite regularly (you are a series producer after all). Your preparation begins 90 minutes before your guests arrive. This time frame is a personal empirical value which you wrote in the margin of the recipe. This note consists of a number of work sequences, which you likewise assigned a minute value to (your processing times).

While the appetizer soup already boils in the pot, you realize, that some important ingredients for the main course are actually missing. Thus, you rush to the supermarket and buy the exact quantity required for your recipe. When you arrive a short time later back at your home, you are greeted by your hungry guests, who surprisingly added another person to their group (your Uncle Ted initially cancelled, but oftentimes comes over anyway). So you hurry again to the supermarket, buy the necessary ingredients, plus an abundant safety stock, in order to be prepared for similar unforeseen events.

Back in the kitchen, you notice that the soup has already been vaporized. So you start again at the beginning and try to prepare the main course in parallel. Unfortunately, you find that you neither have the required amount of pots nor the necessary hotplates (even when ignoring the soup) to realize the recipe as described. At this point, your well numbered plan of working sequences is not worth the paper it is written on. So you call on your improvisation talent, which involves continual re-planning, further delaying the whole process. Your problems exacerbate as one of the hotplates stops functioning (did not your wife warn you of that particular plate?) and at the same time your hungry son decides to make his usual weekend visit. Many hours later you are finally ready, but your disappointed guests have long left. You sit down scowling and eat your portion of the meal. You decide never to cook that recipe again. Meanwhile your safety stock prepares itself for a future membership in the waste chain.

You think this is a very unlikely story? You would check the ingredients before starting to cook? You would probably adjust your recipe to the hotplate capacities or procure more pots? Maybe you would even begin your preparation much earlier?

You are right, inviting some people for dinner almost never looks like this. But if you work in production planning, this is normally considered “best practice”.

Simultaneous cooking with SMPS

But there is a different way: Simultaneous Master Production Scheduling initially checks if material is available and if the production lots can be realized with the given capacities within the planned time frame. This is done in one single step – simultaneously instead of successively.

Besides a simultaneous consideration of all relevant factors, there is another fundamental difference between SMPS and MRP. With MRP you work your production plan step by step and obtain accurately planned process steps to-the-minute. If you transfer this into your kitchen, this would mean that you will need 5 minutes to cut the tomatoes, 2 minutes for seasoning and so on. And all of this in a certain sequence. As you can see, you are planning with a high level of accuracy, which in practice leads to inevitable re-planning and is not really necessary.

In contrast, SMPS bases the planning process on so called bucket planning. This means that you plan feasible time frames (buckets). Although by doing so your plan will be rougher, it will be much easier to realize. The sequence in which you cut the vegetables or prepare the dressing is quite trivial, and can be achieved without a hint of sweat on your forehead. And the most important thing: You deliver your product on the planned date.

If you had cooked using SMPS, you would have known if all your ingredients were in stock for the expected (and not only the invited) guests. You would also not have bought a high safety stock for your storage room, which is typically the case in MRP to guarantee availability (with the risk of exceeding shelf life). Additionally, you would have known about the capacity problem on the stove and thus been pretty clear about the fact that you would not have been able to cook this particular recipe for this particular group of people in this particular time frame. You would have probably started cooking a few hours in advance instead of your fixed 90 minutes. And in the end, you would have been able to serve your guests the dinner right on time and thus receive your deserved praises for your cooking ability.

Conclusion

If you cook your favorite recipe in your kitchen, you will probably use a method which is very similar to SMPS. Thinking of your guests, I would suggest you stick with that method. Thinking of your companies’ production planning I would consider not to wait any longer and break with traditional MRP processes.

Which method do you use in your production planning? Can you think of any more examples where processes in your private life are more efficient than in your company?