Unblocking Your Shop

Increase Your Throughput by Identifying Constraints

Jordan Easterling
Production

To get more done, you just need to work through every problem as you face it, right?

Not quite. The solution might actually be easier than that.

Problems or challenges are inevitable in production, particularly prefab or modular construction. And getting more done—increasing the throughput—isn’t about solving every problem (that’s just not realistic). Instead, take a page from manufacturing process design, called the theory of constraints approach, to identify the weakest link, improve it, and see the whole system improve.

An illustration of constraints

Fixing problems as you face them is known as local- or station-level problem-solving. It’s critical, but it won’t actually improve throughput in the medium or long term. To improve how you operate overall, you need to think about system-level issues.

The mindset behind a system-level approach is that your production is only as fast as the weakest link in the chain. So while you might have a big problem in front of you today, that problem might not be the actual bottleneck or weakest link. Instead, the part of your system causing the most delay might actually be hidden in plain sight.

To identify the weakest link, look at what you’re trying to accomplish then see how the entire process supports it. For example, let’s say you have three stations in your shop: cutting, painting, and assembly. If the cutting station can produce 15 units per hour, the painting station can produce 10 units, and the assembly station can also produce 15 units, which is the weakest link? Assuming you only have one of each station, the painting station is your weakest link, or bottleneck, since it can’t match your other stations in production.

Now let’s say that you noticed a problem with the cutting station that reduced its capacity to only 12 per hour. While you might be tempted to solve the cutting station problem immediately, it won’t actually improve overall throughput because the weakest link—the painting station—has a lower capacity. From a throughput perspective, your resources are better spent first improving the painting station (or acquiring a new one).

5 Steps to increasing your production

Some of these issues are simple and relatively intuitive—like the case of the painting station—but become difficult to notice when you have complex processes or multiple feeder stations that come into the primary line later in the process. That’s when it’s critical to properly identify weak links to improve production throughput.

1. Identify bottlenecks

The most visual way to identify bottlenecks is to ask yourself where orders stack up in the production process. In the painting station example, you’d probably notice more orders coming from the cutting station, getting held up at the paint station, and then trickling down to the assembly station.

Sometimes bottlenecks also show up at the station after the real issue. In the paint station example, you might first notice that the assembly station is not putting out much. However, that’s cause the real issue is the hold-up at the painting station, not the capacity of the assembly station itself.

For more complex systems, look at low-tech solutions like daily counts (on spreadsheets or whiteboards), or daily meetings. Once you are tracking daily counts, it’s critical to understand utilization at each stage, station, team or through each piece of equipment (for example, calculating the Overall Equipment Effectiveness ratings for quality, speed, and interruptions).

As you get more data-focused—which is necessary for multi-step or complex processes—automate measurement with a purpose-built modular and prefab construction tool.

2. Assess bottlenecks for quick solutions

Once you’ve spotted the weak points, the ideal solution is to increase capacity at those stations to the level of the rest of the system with what you already have, today. That’s usually accomplished by one of three things: more space, a new policy, bigger teams, or different materials. In our paint example above, allocating more paint areas and increasing the size of the paint crew may allow for higher throughput through that process step.

After figuring out what kind of adjustment is necessary, then apply the adjustment to keep the increased throughput going.

3. Refocus to serve bottlenecks

If you can’t spot-fix weak points in your production flow, think about the whole process. For example, the best solution might be to slow down production in other areas while working on an iterative improvement to your weakest link. This might not seem intuitive, but slowing down can actually improve the whole system; take the cutting-painting-assembly situation.

If the cutting station is sending 15 units per hour to the paint station, there will be a 50% bottleneck every hour that requires additional storage and time to work through in the paint station. This might mean the painting station has to work additional hours to make up the backlog, incurring both overtime labor costs and running the machine down faster and requiring higher maintenance costs.

But a combined effort to improve the paint station to 12 units and slowing down the cutting and assembly stations to 12 units will still increase overall throughput by 20% (from 10 to 12 units per hour). Even though you technically slowed down production in large parts of your shop, you’ve increased throughput and reduced both overtime labor and additional maintenance costs.

4. Elevate bottlenecks

Small fixes and ingenuity won’t solve long-term problems. As you think about the future, work with your leadership team to identify sustainable long-term solutions that will require both effort and resources.

The most common pathways are:

  • Add new production equipment—R&D can help a lot here, particularly when considering automated equipment.
  • Work with third parties for parts of your production system—you may need full team backing and resources, but sometimes an alternative perspective may help.
  • Use technology to help map your system and spot bottlenecks—make sure you’re buying purpose-built platforms so you don’t need expensive consultants to configure everything.

5. Repeat

If a bottleneck breaks or a new one forms, start this process over again. And remember that system-level improvement requires continued refinement over time. As you fix one bottleneck or weakest link, you will inevitably spot another. This is not a bad thing! Spotting more problems doesn’t mean your system is low quality—rather, it means you’ve improved to such a level that what was previously good is now ready to be improved.

As you get used to the concepts of weakest links and bottlenecks, the good news is this is a well-worn path in manufacturing (people have long studied the Toyota Method). There are a wealth of resources available on this subject well beyond this blog, such as The Goal, a novel by Eliyahu Goldratt. Yet this mentality is not that common in prefab and modular construction—opening an opportunity for you to increase your throughput while competitors wonder what you did right.

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