Breaking Technology on Single Setups

(Written by Chuck Birkle of Mazak Corporation, and published by Modern Machine Shop Magazine, Mar-96)

Setting Up For Single Setups
How do you minimize unit cost for complex parts in need of turning, milling, and drilling? For Steve Hattori, the answer is simple: Machine them with just one setup-- and make that setup as simple as possible.

The president of the contract shop, Salinas Valley Precision, Mr. Hattori used to need a minimum of three machines to produce any complex round part from solid: a bandsaw to cut the stock to length, a lathe, and a machining center to add flats and holes. Now he lets a single machine do all of this work-- converting uncut barstock into finished parts automatically, effectively replacing numerous setups with a simple, single setup.

"Anyone who would argue for the old way has never tried to machine a fishing reel!" says Mr. Hattori. In fact, the first time a local sporting goods manufacturer offered him the part, Hattori declined. Back then, the part was too complex to be profitable. Cut from solid aluminum with 90 percent of the stock machined away, the 3.250" diameter reel consists of two easy-to-warp flanges less than 0.100" thick, connected by a hollowed-out core with walls not much thicker.

The part has to be attacked from all sides. Each flange is penetrated by 12 holes, 0.450" diameter, which serve to reduce weight. The core circumference includes 12 oval-shaped weight-reduction slots as well. Finally, a counterbore on one face includes 36 serations for the fishing rod ratchet mechanism, plus a press-fit bearing bore with a total tolerance of 0.0002" on diameter.

"And all that geometry was only half the problem," says Mr. Hattori. "The rest was batch size. We could have machined the part using complex fixtures on the machining center, along with the CNC lathe we were using at the time. But this would have incurred a large setup cost, one that was impossible to amortize over the part's small run-- often as low as 100 pieces." In order to make this complex part a money maker, Mr. Hattori called on Mazak, and together, the two companies reinvented the process.

One-Stop Machining
The key result of Mr. Hattori's ingenuity is a process where all turning, milling, and drilling operations are combined on a single machine-- a Mazak "Super Quick Turn (SQT) 15MS-Y" CNC Turning Center. Besides carrying a complement of rotary tools for milling operations and an opposed second spindle for second-side turning, the machine is equipped with a programmable Y-axis with four inches of stroke. This Y-axis capability allows off-center milling operations to be performed while the workpiece is still held in the primary or secondary spindle.

Through coordinated, automatic hand-off between the two spindles, every surface of the part can be reached without any human intervention. Every turning, milling, and drilling operation is performed without "turning loose" of the part, thus maintaining critical workpiece position references throughout the entire machining process.

What About the Cutoff Saw?!
Workpiece blanks are fed to the Mazak Super Quick Turn with a Mazak CUT-FEEDER. Just as the rotary tools take the place of a secondary machining center, the Cut-Feeder eliminates the band saw from the process, and it cuts the delay between consecutive part cycles to just a few seconds. The Cut-Feeder not only advances the stock, it cuts it to length, from 0.600" to 5.110". It executes this cutoff externally from the turning center, while the SQT machines the current part. Then the Cut-Feeder loads the new workpiece into the left chuck as soon as the lathe is ready for the next cycle.

The automatic Cut-Feeder helps minimize setup time. The unit stores up to five of the 3.250" diameter 12-foot bars used for the fishing reels-- and advances and cuts each one without bar rotation. Rather than a conventional hydrodynamic barfeeder which allows the entire bar to rotate while machining, the Cut-Feeder holds the bar stationary and rotates cut-off tools around the stock. Because the bar never rotates, no pre-machining is needed to make it round (even square and hexagonal stock work). As a result, Mr. Hattori can simply drop one or more bars into the feeder and let the turning center convert them into finished machined parts. The machining process involves 20 tool changes, but requires no operator, so Mr. Hattori lets the machine run unattended-- getting back 90 reels for each 12-foot bar. The single setup concept offers "lights-out" capability with very little fixturing cost (2 sets of soft jaws), and very little labor cost.

Return On Imagination
The reels come out of the turning center at a rate of one every eight minutes. "The Mazak multitasking lathe provides greater payback for a programmer's imagination than any other I've used," says Hattori. "With so many options in one machine, there's always another way-- and oftem a better way-- to produce any feature."

If you have similar challenges with complex parts and their costly setups, E-Mail us or call us at (586) 741-3000 (In Michigan, call toll free 1-800-ADDY-NOW). We can turn headache parts into money-makers for you, too!

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