Roaring success can challenge all of your assumptions about the right way to run a business. Methods that worked before start to break down under the demand for more and more throughput, and all hands must chip in to keep success from fading to black. At the Fabrication Division of Boeing Commercial Airplane Group (BCAG) in Auburn, WA, for example, the machine shop infrastructure had to change to help meet the demand for 737 and 777 commercial aircraft.
A huge operation, the Fabrication Division occupies 475,000 ftz (44,175 m^sup 2^). It has 900 employees and a tremendous array of internal systems and vendors. Managers at the Fabrication Division quickly determined that they required more than machining technologies to achieve Boeing’s goals. “A cultural change was needed. We needed to build relationships internally and externally that didn’t exist before, says Don Proctor, a BCAG machine shop MBU manager.
“Especially since this division began building wing package parts-specifically rib posts-we recognized that a new approach to manufacturing support would be necessary,” adds Ron Oxford, a BCAG general supervisor. Rib posts are used as spar stiffeners and they mate to camber stringers or spars within a wing. Depending on the aircraft, there are 200 to 400 rib posts in a wing, each 6′ to 5′ (150 mm to 1.5 m) tall.
Lean, High-Speed Action
BCAG’s Fabrication Division investigated technologies from several manufacturers and chose a combination of high-speed machining within lean manufacturing cells to help improve capacity rates. Previously the machine shop dedicated specific areas to roughing, finishing, and holemaking. By contrast, lean manufacturing aligns each part, or a set of parts, from a particular section of an airplane with a cell.
“Cells cut down on time delays caused by parts moving from one end of the machine shop to the other end and nearly eliminate work in process,” says Tom Johnson, a BCAG factory superintendent. “When a rib post is manufactured in one cell, its team of operators owns the processes. From machining and deburring to inspection and part making, each cell focuses on one part family.”
The first rib-post cell installed in the machine shop uses four Makino (Mason, OH) MC98 horizontal machining centers. When organized into a cell configuration, the MC98s maximize spindle utilization by shuttling pallets and managing workflow so that operators can work ahead of the machining center and eliminate set-up time. In this way, numerous qualified fixtures can be stored in queue, complete with fixed tooling and offsets for the cell.
All four MC98s are four-axis highspeed machines that cut at approximately 380-400 ipm (9.7-10.2 m/min) using precision-balanced milling chucks on 15,000-rpm spindles. The Model C cell control software directs the cell vehicle and its 44 pallets. This software package allows automatic tracking of multiple operations in a single cell for as many as 600 part numbers. It also handles job priority scheduling, NC programming management, pallet routing, tool life management, multiple programs per pallet, and presetter interface.
KOMO