In many but not all collision centers, the paint shop or specifically the paint booth is the constraint or “bottleneck” of the system. In other words, since nearly every repair job has to flow through this resource, it can easily become backed up with excess inventory (jobs waiting in line to get painted.) What Eli Goldratt’s Theory of Constraints teaches us is that the system’s constraint is what dictates our overall throughput, or in other words, the amount of money a shop can make is dependent upon how many repair orders you can run through your paint booth.

“An hour lost in a constraint resource is an hour lost forever.”

What amazes me is the amount of effort people put into making the other departments more efficient, when the added efficiency they create makes no contribution to allowing more work to flow through the paint booth. This is the fundamental difference between “Lean Thinking” and Theory of Constraints. Think of it like this:

If your paint booth is a constraint in a shop operating at $150,000 a month with one paint booth, during an 8 hour workday the booth would be allowing $893 dollars an hour to flow through it.

($150,000 divided by 21 working days, divided by 8 hours equals $893)

So if your booth is broken, or a painter is taking a late lunch or you’re re-spraying due to poor workmanship, it is costing your shop $893 an hour! How does, $15 a minute sound? When you think of it in these terms, it really opens your eyes, doesn’t it? It makes you a little more protective of that resource!

What Theory of Constraints suggests is to Exploit, Subordinate, and Elevate the constraint in order to increase your throughput and profitability. Here’s a few examples on how to do it.

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Exploit – Use the paint booth as efficiently as possible.

  • Try to always keep a car ready to roll in the booth so it never sits empty
  • Have a car prepped and ready to paint first thing in the morning
  • Hours of operation. Can you extend the hours the booth operates?
  • Regular booth maintenance to eliminate mechanical failures (done after hours if possible)
  • Regular booth cleaning and filters replaced (done after hours if possible)

Subordinate – Everybody in the shop knows the booth is to be catered to!

  • Never send flawed work to the paint shop
  • Always make sure the painter has the parts and paperwork he needs so he/she isn’t wandering around looking for it.
  • Make considerations that will keep the painter in the booth spraying such as:
    • Tinting outside the booth
    • Mixing
    • Masking
    • Ordering product
  • Body men are always aware when they must have their work shipped to the paint department

Elevate – Make the department or resource bigger

  • Robotic drying equipment or other equipment to dry paint faster
  • In some cases it may be preferable to add another booth or prep station
Scheduling to the Constraint

I think the best way to exploit the opportunities in your paint booth is through your scheduling habits. Far too many collision repair shops continue to bring a majority of their repair jobs in on Monday even though they know it is wrong! Most smooth running shops will paint close to the same number of vehicles every day. For our sample shop with sales of $150,000 that is going to equate to around 3-4 cars needing to be produced a day. A very achievable task for most shops with a single booth. However because of poor scheduling habits many paint departments continue to do almost no cars on Monday, start prepping a couple on Tuesday and then get completely overwhelmed on Wednesday afternoon and Thursday to get ready for the big “Friday Push!” It’s no wonder so many painters think they need another paint booth and a faster paint system when all they really need is for management to fix their scheduling habits.

Drum, Buffer, Rope

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A Theory of Constraints analogy is what they call Drum, Buffer, Rope, (DBR) In the book called The Goal. Eli Goldratt uses a DBR story to describe how they keep a group of boy scouts marching at the same speed to ensure they all arrive at their destination at the same time as quickly as possible.

The Drum beat follows the speed of your constraint resource. An example of this, is that all body shop departments work to keep in pace with the paint booth.

The Buffer (a small buildup of work) ensures that the constraint never runs out of work. (Remember $893 an hour!)

The Rope is tied to your scheduling of work coming in. In other words, you schedule your repair jobs in as your constraint can begin working on it. As with lean thinking, scheduling too many repair jobs in leads to excess inventory (waste.)

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This article uses the example of the paint booth as the constraint resource because it is very common in our industry. However, this is not always the case, in fact, in many collision centers the office and blueprinting operations are commonly the bottleneck. So wherever your bottleneck is you can still use the same thinking to make sure you optimize your collision center for throughput and profitability.