Double output from single cells

Sept. 1, 1999
A single-cell machining system with dual spindle modules provides flexibility for lean manufacturing along with the aggressive production rates of a transfer line.

A single-cell machining system with dual spindle modules provides flexibility for lean manufacturing along with the aggressive production rates of a transfer line.

Kirby builds the Bordoflex's critical components onto one base, and all service access is from the rear. This means the machining cells are easily moved and integrated into manufacturing lines.

The Bordoflex from Kirby, Statesville, N.C., is not a transfer line and not quite a machining center. It's an agile machining cell with independent dual spindles, heavy duty turret heads, and a rotating table. This design, along with other features, makes the machine flexible without sacrificing efficient output.

For one U.S. automotive components manufacturer pumping out 65,000 parts daily, the Bordoflex is part of a lean manufacturing vision that involves single-piece flow, cellular-type concepts, quick changeovers, and flexible equipment. The manufacturer will use Bordoflexes to produce a new part similar to one currently being made on dial-type machines. The part, which has been running three years, is changing, and the company expects further revisions down the line. Retooling the existing machines was not a cost-effective option, and the likelihood of future part changes made any other dedicated-type system less attractive.

By going with the Bordoflex, one machine will produce complete parts as opposed to two machines splitting the process. As one company engineer puts it, "every part went through dedicated machines, and if one went down, the whole line stopped." By purchasing two Bordoflexes, the company will have a backup machine to alleviate this problem.

Another benefit of the Kirby Bordoflexes is that they have three part fixtures on the rotary table — one up front for loading/unloading and two at the machining stations. Each fixture holds two parts and rotates to split the machining operations between the two stations. Previously, the company was using two separate dial machines, which entailed two setups and two chuckings.

"Customers are constantly raising their standards," says one engineer at the plant, "and the Bordoflexes will hold these ever-tightening positional tolerances." In fact, a single machine producing complete parts means better quality because workpieces are chucked once instead of having to move from one machine to another halfway through the process.

Repeatability problems often arise from having to chuck parts twice.

Two three-axis modules, each with a six-spindle turret, do the drilling, tapping, reaming, and milling on the Bordoflex. Eight spindles are standard, but running fewer makes room for bigger bearing construction, which means more power to the tool, especially for milling. Being able to mill with the turret also means the plant can replace a costly broaching operation and reduce tooling costs.

Because Kirby keeps the footprint small, the machines will fit into the same floorspace once occupied by the two dial machines, with plenty of room for accumulators, conveyors, and an overhead gantry robot. "Our system puts increased machining power and options into the same amount of space, enabling the customer to perform more operations with less equipment," says Mark Abell, a senior applications engineer at Kirby.

Part of the reason is that all the Bordoflex's critical machining components are kept on one base. There are no doors on the sides, and all service access is from the back. Easy mobility along with simple setup let the customer move machines to new locations, if need be, and integrate them into other lines.