Volume 7, Issue 10 - November 2006

Software Savvy

Lean Manufacturing
It Doesn’t Have to Decrease Lineal Yields

by Ron Crowl

You know you’re taking a hit from the escalation in vinyl and steel prices. You also know it’s almost impossible to pass these increases on to customers.

Here’s something you might not know: lean manufacturing can make these losses worse. Some of you have already made this unpleasant discovery. If so, you’ve likely accepted that the more you achieve true lean manufacturing, the more you’ll decrease lineal yields.

Lean is no fad, as its many proponents will testify. It provides real improvement in efficiency and other areas. How can it possibly increase material waste in a door and window plant?

The answer is straightforward. 

Lean creates efficiencies by decreasing batch sizes. If you decrease batch sizes, you must increase the number of batches to make the same units. Your lineal optimization application, on the other hand—if you even use one—is most efficient with the largest batch size possible.

It gets worse. Existing lineal optimization programs were developed for much larger batch populations than seen in all but the biggest door and window plants. By implementing lean, you take an already small batch size and reduce it. 

As far as we can determine, all lineal optimization programs can pull only from one batch. In addition, existing algorithms calculate for material costs only. Failing to include labor costs further reduces effectiveness. 

The solution is not to abandon either lean or optimization. Lean is good. It reduces work in process, drives labor efficiency and reduces overall inventory. 

If push came to shove, an analysis would likely show your benefits from lean outweigh your losses from decreased lineal yields. If you gave up one, it would be lineal yields.

If the problem is not lean, what is it? At least as far as small batch operators are concerned, it’s inflexible lineal optimization tools. 

If you’re not going back to just one big batch—and you shouldn’t have to—then what is needed is significantly different thinking about lineal optimization plus new ways to calculate and manage it in your plant. 

You can’t just add the ability to pull from every batch in a schedule. That would create unmanageable amounts of work in progress. You’d need to add storage space. 

What’s needed is flexibility. Yes, you want to pull from more than one batch. But you need to be able to pull from a wide or narrow range of batches depending on material cost, saw capability, labor cost and other factors. For high-volume lineals, for instance, one batch might be fine. For high-cost and low-volume lineals, you want to pull from all eight or 10 batches in a typical lean shift.

You also want flexibility in control. You want to be able to set your parameters and forget about them. 

If you could do all that, if you could change how you optimize and cut materials, you would increase yields dramatically and improve your bottom line. You could have lean manufacturing efficiencies and high lineal yields.

What should you do? Compare lineal yields pre- and post-lean implementation. Get over the shock, then work to understand where your labor and material waste come from. A typical frame saw operator will consume 25 to 30 times the cost of the labor. A three percent yield improvement can pay for the labor!

Ron Crowl is the president of FeneTech based in Aurora, Ohio. He may be reached at ron_crowl@fenetech.com.

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No reproduction of any type without expressed written permission.