Description of moving line: Adapted from automotive Lean manufacturing methods in Japan, a continuously moving assembly line slowly moves products from one assembly team to the next. This technique keeps production moving at a steady pace, allowing employees to gauge production status at a glance and reducing the amount of work-in-process inventory.
Benefits of the moving line: Moving assembly lines, and the accompanying Lean techniques, enable a smooth, continuous production flow, enhancing the quality and efficiency of production processes. The line is stopped when an abnormal condition occurs. Stopping the line is the visual that tells us an abnormal condition exists and needs to be quickly addressed. In addition to reducing flow time and production costs, moving assembly lines also create an environment that makes it easier for employees to do their jobs. All the tools, parts, plans and work instructions are delivered to employees so they have everything they need where and when they need it.
How Commercial Airplanes implemented the 777 moving line: Boeing Commercial Airplanes used a phased approach to implement the U-shaped 777 moving production line.
One by one, the positions in the u-shaped line were made "move capable" beginning with systems installation, then final body join and ending with final assembly. In January 2010, the 777 u-shaped production line began moving simultaneously, becoming what's believed to be the largest integrated moving line in the world.
How the airplanes are moved: In systems installation and final body join, the fuselage sections are moved on crawlers that follow a metal strip in the factory floor. In final assembly, the airplane is pulled by a super tug that fits around the airplane's front landing gear. The tug has a sensor that follows a metal strip in the floor. The 777 u-shaped production line moves at a rate of about 1.8 inches (4.6 cm) per minute.
Implementation Milestones:
- Aft Systems installation relocated from 40-26 bldg. to 40-25 -- March 2006
- Aft fuselage sections placed in crawlers for systems installation -- March 2006
- Airplanes in final assembly placed nose-to-door -- June 2006
- Forward fuselage sections placed in crawlers for systems installation -- July 2006
- Began moving airplane in final assembly during production -- October 2006
- All crawlers in systems installation begin moving in production -- July 2007
- Final body join "move capable" on crawlers -- December 2007
- a one-bay u-shaped moving line for 777 assembly -- July 2008
- All positions in u-shaped line begin moving at the same time -- January 2010
Improvement achieved: (measured between 2003 and 2009)
- Factory build time reduction -- 24%
- Factory unit hours -- 34%
- Inventory turn rate -- 71%
- Lost workday case rate -- 37%