Why Setups Are the Real Bottleneck in High-Mix Machining

“Everybody has a mindset that manufacturing is production,” says Dustin Sanks, president of Sanks Machining, in Julia Hider’s recent feature article. “Well, what we do on repeat is not pulling parts out of the machine — it’s putting tools in the machine.”

In other words, he says, their production focus is on setups as much as parts.

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Each machining setup has consequences that impact cost, yield and throughput. In a high-mix shop, it is the predictability of recurring setup work that validates the act of cutting metal: selecting and locating tooling, loading and measuring tools, establishing offsets, fixturing, probing and then confirming that the program and tool condition are all equal to the task. Each action takes time, and each action introduces an opportunity for variation.

Sanks actually assigns a number to the hidden work. When quoting, his team used to budget 20 minutes to find a tool, put it in a holder and set it. If the alternative is an additional minute of machining with a tool already loaded, that extra minute is a much lower-cost option than the time it used to take when repeating a setup.

You’ll find a similar logic in Weingärtner’s turn-peeling study, but under harsher conditions. The part is a 3,900-mm rotor in a 316L-type stainless, and the main turn-peeling cycle is about 150 minutes. Tool changes are challenging because the peeling head runs off-center and access to it is so limited that each change can take upwards of a half hour. A change can also disturb surface finish or, worst-case, damage the workpiece and head. Under those conditions, extended tool life becomes an absolute requirement.

Is this the most meta-version of a column called “The Setup” ever written? Yes or no, you’ll find several feature stories in this issue that tackle strategies for reducing the number and cost of setups.

Back at Sanks Machining, it’s all about scaling back the number of handoffs each part makes during its production. Take, for example, a part that includes a turned pin with a flat and cross hole, plus a drilled and tapped feature on the back side. In a two-machine workflow, that requires at least one additional fixture and one additional setup on a mill after turning. Putting those features on a lathe with milling capability reduces refixturing and compresses the number of times a part has to be re-established in a new reference frame.

Or consider bringing turning to a mill with a U-axis head, as Derek Korn describes in his recent feature. A U-axis head enables a VMC or HMC to perform turning and boring by adding controlled radial motion perpendicular to the spindle centerline. For many shops, the benefit is avoiding a transfer for large workpieces or for parts that are predominantly milled but include contoured bores. There are constraints to contend with — some heads trade rpm for torque, for example — but this option comes at a fraction of the cost of a vertical turning lathe or multitasking machine.

Another strategy along these lines is standardizing tooling that enables shops to make fewer tooling decisions per job. Drilling inventories can become unwieldy because the options across diameter, L×D, substrate and coating are seemingly endless. Tungaloy’s DrillMeister system uses modular heads and bodies to cover a range of applications without stocking a complete drill for every combination. Its cam-lock connection supports quick head changes with repeatability “within tenths,” reducing the need to re-touch-off after a change and reducing downtime.

Tool stability can also decrease setup requirements by reducing mid-cycle tool changes. In the turn-peeling case, Kennametal’s KCU25B grade held the finish and chip control throughout its predicted life. This level of consistency and durability helped Weingärtner and Kennametal stabilize the process and push parameters further, ultimately reducing machining time from 150 to 126 minutes with consistently good results.

And then there is the concept of pushing complexity upstream into programming — a third theme, if you will — allowing setups to be repeated without relying on tribal knowledge. Sanks still remembers the “lightbulb moment” when he was trying to learn Mazatrol conversational programming. He estimates that standard parts that once took roughly two hours to program could be reduced to about 15 minutes. He also lays out a hybrid approach in which more intricate features are programmed offline and inserted as subprograms.

U-axis adoption can offer a similar benefit: When a new capability fits an established workflow and verification is robust, it scales beyond one expert.

Finally — and bear with me here — the “How I Made It” interview with Mastercam’s Clint Smith frames training as a different kind of setup condition. As Smith says, “We have over 170,000 installations of Mastercam in educational institutions around the world.” Early exposure to widely used CAD/CAM reduces ramp-up time and makes modern programming approaches less of a foreign language to new hires.

If you want to do a quick diagnostic test, count your setup-related steps on a typical job: refixturing steps, tool changes that require touch-off, program edits at the machine, and tasks that depend on one person’s know-how. Then choose one event to eliminate by consolidating an operation, standardizing a tool set, reducing a tool-change point, or converting a manual decision into a repeatable program and fixture plan.

And if you do that, you really should consider taking the Top Shops survey, which is open now through April 1. The survey provides a way to benchmark all of the factors — like setups and associated times — that exist between cuts. High-mix makes cycle time hard to compare directly, but setup discipline is measurable: routing choices, tool standardization, programming workflow and skills development. This issue offers multiple routes to fewer and more repeatable setups, and that is capacity you can plan around.