Lean from the get-go: this shop's visual management tools form its lean manufacturing foundation

Modern Machine Shop, July, 2005 by Derek Korn

Once the bottleneck is fixed, Herbie goes somewhere else in the manufacturing process and must be found again. In such cases, a more costly special tool or vise may be appropriate if it solves the prime bottleneck. Milling capability was R&D's most recent Herbie. Though its first VMC remained capable of performing its machining duties, it became overworked and couldn't keep up with the speed at which the CNC lathes fed it work. This bottleneck opened with the addition of a second VMC.

Walk Through

Each work day at R&D ends with the partners taking a quick walk through the shop, looking at the on-deck boards and/or job folders to get a sense of whether or not scheduling changes are necessary. Then the following morning, the two meet with all workers to discuss any "hot" jobs, which can change daily. The visual tools are one way that the shop can change gears quickly to keep up with changing customer needs.

Mr. Malone sums up the visual factory concept in this way: "If everything is identified and shop work space is just large enough to hold what you need--and only what you need--then you eliminate the ability to create waste."

The Big Turn

R&D has one of the largest CNC lathes in South Florida--a Daewoo Puma 300 that offers 4-inch through hole and 18- inch diameter capacity. The used (though barely used) lathe was purchased through Arthur Machinery based on the chance to win a job turning and threading aluminum air purification cylinders. These cylinders are 32 inches long with a 4-inch-diameter bore and a DIN 405 rounded-type internal thread on both ends. The purchase was a leap of faith in the shop's lean system, and also required faith in the customer that it would not cancel the job (it didn't).

A custom, harmonically balanced boring bar from Sandvik Coromant (Fair Lawn, New Jersey) is used to turn the cylinder ID. The bar had to be 24 inches long in order to reach more than halfway into the tube. The tube is then removed, reversed and re-chucked to allow machining of the other half.

There was a concern that the weight of this boring bar might cause the lathe's turret to over-index slightly, which would affect the accuracy and repeatability of the boring bar's position. It was especially important that this not happen, because each half of the tube's ID is machined in separate operations and the cuts must meet seamlessly. However, Mr. Malone explained that after the first run of parts, the last tube was just as spot-on as the first.

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* This Shop Really Shines ... And Sorts, Simplifies, Standardizes And Sustains The 5S principles are proving to be a powerful prelude and prerequisite to lean manufacturing at this aerospace job shop.

* The Technology Of Lean Machining This plant makes different choices for its machining cell designs depending on whether the parts are known or unknown.

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