How can food producers optimize production when each part of a production system moves at its own pace? The Theory of Constraints holds the answers.

Imagine escorting a Scout troop single file along a narrow trail. It is not going well. There are Scouts right on your heels, which is right, but somewhere behind the pace is much slower. Wide gaps open up and stragglers wander off the trail.

You demand a faster pace and the Scouts oblige to the best of their ability, but now you find a new problem: the faster you go, the more spread out your Scouts become. The gaps between them widen and you scramble to keep the whole line moving without losing anyone. Some kids are practically sprinting, but the group as a whole isn’t moving any faster than it was.

As you reverse course down the line to investigate, you discover Herbie, who just isn’t hacking it. He’s slow, nobody can get past him, he’s way behind the kid ahead and everyone else is bunched up behind him.

This scenario comes from The Goal — a classic work by E.M. Goldratt that introduced the world to the Theory of Constraints — and it serves as a parable for a challenge faced by all manufacturers: how do you optimize a sequence of operations when each part moves at its own pace?

Anyone working in food production knows the consequences of sub-optimal operations. They look a lot like the Scout parable: parts of the system are moving fast, but other parts are slow. Some parts that could move faster are being held up by slower parts downstream. Big gaps appear between production steps where nothing much is happening and inventory sits idle.

Seeing the problem is easy enough, but what can a manager do about it? How do you cope when instead of slow Scouts you have slow output, and instead of stragglers and gaps, you have perishable goods sitting still, generating inventory holding costs and losing freshness (and value) every day?

The Theory of Constraints gives us a framework for analyzing and solving these problems, and is based on Five Focusing Steps, summarized below.

 

    • Step 1: identify the constraint. Think back to the Scout troop example, and what happened when we demanded more speed. Some parts started to move faster, but as a whole the group didn’t make quicker progress. There were still lots of kids stuck behind Herbie, and in some areas the kids were bunched up while in other areas there were huge gaps between them.The Theory of Constraints codifies an important lesson from that example, and it’s this: the only way you can speed up production is by focusing on the constraint — the bottleneck — which in our example is Herbie. A system can only move as fast as its slowest part, so if you want to increase the speed of the system, you’re wasting your effort if you spend it anywhere other than on the bottleneck. Doing so only increases unevenness, not production output.

 

    • Step 2: squeeze as much utilization out of the bottleneck as possible. It’s important to do this before thinking about expanding the bottleneck by buying more machines, hiring more people or otherwise throwing money at the problem. You first need to get everything you can out of what you’ve got.And if you examine your bottleneck closely, you’ll probably find lots of room for improving utilization without spending lots of money. Herbie’s backpack can be lightened so he can walk a little faster. Snacks can be eaten on the go to diminish idle time. Until Herbie is really giving 100% of his effort to forward motion, you have more work to do before moving on to the next step.

 

    • Step 3: subordinate everything else to the constraint. By definition, any part of your system moving faster than the bottleneck is creating excess work-in-progress that has nowhere to go. That’s why the bottleneck needs to become the system’s pacesetter. If Herbie sets the pace, evenness is restored and excess production disappears.Subordinating other parts of the system also means that, now that the bottleneck is setting the tempo, it has to have the whole system’s support to maintain that tempo. A buffer before the bottleneck can make sure it’s never starved for work. Performing quality tests before the bottleneck rather than after mean its effort isn’t wasted on defective products that can’t be sold. Align all parts of the system to keep the constraint at 100% utilization.

 

    • Step 4: elevate the constraint. When there’s no more utilization to be squeezed from your bottleneck, you can consider increasing its capacity by buying more machines, hiring more people, and so on. Just remember, the greater return on investment is in increasing the capacity of the equipment and people you have. Be sure to do that before buying more people and equipment.

 

  • Step 5: if you’ve succeeded in transforming a bottleneck into a non-constraint, start over from Step 1. Every system has a constraint, just like every Scout troop has a slowest hiker. If some other part of your system is now bottlenecking throughput, identify and address it with the steps above. Never become complacent, and never stop searching for constraints and systematically applying the steps.

While any production facility can benefit from reduced inventory and improved equipment utilization, things become even more critical when your inventory needs to be refrigerated at great cost, or when idle inventory goes stale, costing you money and goodwill with your customers.

For food producers, poor inventory management creates costs where before there were none. For example, dough needs to be refrigerated but its raw ingredients don’t; overproduction increases refrigeration expenses.

As well as those extra expenses, food producers also face the added complication that timing can have a serious effect on the finished product. Proofing and fermentation need time, but not too much. Achieving evenness and predictability in your operation is all the more important when time is an ingredient.

To remember the basic principles here, think DRUM-BUFFER-ROPE, a mnemonic developed by Goldratt to make things a little easier. Your constraint should be the drumbeat to which everything else moves. A buffer before the drum keeps the drum beating steadily. Rope makes sure nobody gets too far ahead of the drummer, checking overproduction.

You’ll never tear your hair out over Herbie again.

If you enjoyed this article, check out our Beginner’s Guide to ERP Software for Food Processors

How are you managing your constraints? Tweet us @JustFoodERP.

 

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