Theory of Constraints: 'Blue Light' creating capacity for nothing (2007)

Source: Hacker News

The Essence

The story illustrates the essence of the Theory of Constraints as a process for exposing and challenging the assumptions that block us from seeing better solutions.

Our assumptions cause us to accept things as facts—often without checking them—and limit us to looking for a solution within a false frame that prevents us from seeing a simple way out.

If you’re familiar with the classic brain‑teaser of the nine dots (a 3 × 3 grid) where you must connect all the dots with four straight lines without lifting your pen, you’ll understand the point. (If you haven’t seen it, let me know and I’ll post it.)

The Situation

I was very young—only about a year into consulting—when a company asked me to look at a capacity problem in one of its plants.

• Product: Heavy‑metal bumpers for semi‑trucks.
• Bottleneck: The welding department.
• Current state: Orders backed up; the plant ran at capacity 24 × 7.
• Planned fix: Expand the building to add three more welding bays, doubling capacity.

The plant manager told me early on that the department was running at 93 % efficiency, basically saying there was no room for improvement. My experience told me that there is always at least 25 % more capacity that can be exposed in any plant.

I wasn’t fazed and finally convinced him to let me observe the welding operation.

My “Blue Light” Mental Image

Whenever I go out to look at an operation, I form a simple picture of “what good looks like.”
Because I’m a completely non‑technical person, the image I kept in my head as we walked onto the shop floor was “blue light.”

If the welding torch isn’t turned on, emitting its funky blue light, the welders can’t be welding anything.

So I decided to look first for how much of the time there was blue light coming from each of the three welding stations. (Yes, this isn’t the ultimate indicator of optimal performance, but it was more than enough for this case.)

What I Observed

1. First welder

   • Turned off his torch, removed protective gear, and walked to his buddy’s booth.
   • Both men lifted a finished bumper off the welding table, placed it on a pallet, and put a new, unwelded bumper onto the table.
   • The first welder then peeled the protective plastic coating off the bumper (using his fingernails—a time‑consuming task).
   • He clamped the parts, put his gear back on, and welded for no more than 30 seconds.
   • In the five minutes I watched, he welded for 30 seconds (≈ 10 % of the time).

2. Second welder

   • Returned to his empty booth, pushed a trolley, and moved his finished pallet to the next operation.
   • Spent several minutes locating the next skid of bumpers, moving other pallets out of the way, and then moving them back.
   • Zero blue light during this whole maneuver.

3. Third welder

   • Went to the store room to fetch parts, returning only after several minutes.

The two‑man “bumper‑lifting dance” repeated several times while blue‑light time remained well under 10 %, probably far lower.

The Plant Manager’s Reaction

While I was thinking, “Wow, did I sandbag this guy?” (i.e., the plant manager), I told him there was 25 % more capacity to be uncovered.

He turned to me and said something I have never forgotten:

“You see, they’re busy all of the time!”

He was right—the guys were busy and working hard, but busy does not equal productive.

The Lesson

What amazed me was how the two of us could look at exactly the same thing and see it entirely differently.

• Plant manager’s assumption: “Good looks like people being busy.”
• My perspective: “Good looks like the operation actually producing work—blue light on the torches.”

His assumption blocked him from seeing any solution other than adding more capacity (the three new welding bays).

By challenging that assumption and focusing on the real indicator of work—the blue light—I could expose the hidden capacity and point the way to a true improvement.

Takeaway

In any organization, question the assumption that “busy = productive.” Look for the real measure of work being done, and you’ll often uncover a substantial amount of hidden capacity.

Improving the Welding Bottleneck

The original plan was to add people, which would have required a costly expansion of the plant and months of implementation. During that time, customers would become increasingly frustrated, and the company would lose hundreds of thousands in potential profit.

To make the story a little shorter, we ultimately implemented a very simple solution:

• The department had a summer worker in another (non‑constraint) area who knew nothing about welding.
• We moved him into the welding department to act as a “helper” for the welders.
• We gave him a simple metric: more blue light from the welders’ torches.

His responsibilities included:

1. Lifting bumpers with the welder.
2. Moving pallets of bumpers around.
3. Staging the next jobs for each welder.
4. Preparing all parts the welders needed.

If he had extra time (which he did), he was to peel the plastic for the welder and do anything else that would generate more blue‑light time.

In less than three weeks they had completely cleared the work‑in‑process area. This backlog shipped out along with the ongoing flow to welding, producing a record‑shipping month. I don’t know exactly how much capacity was created, but it was more than enough to break the bottleneck, and any additional capacity could have been generated just as easily.

What limits us as individuals and as organizations are the assumptions we hold, and our failure to recognize them as just “assumptions” rather than facts.