Aluminium frames play role in lean manufacturing
25 November 2010
Aluminium framing is playing an important role in ensuring the continuous flow of airline passenger seats through a lean assembly operation at C&D Zodiac’s dedicated manufacturing site in Ontario, California
C&D Zodiac manufactures a range of components for commercial aircraft cabin interiors, but aircraft seats are its speciality, and its Ontario, California site turns out 1,200 passenger seats per month. The company recently converted its production line from a batch and queue system to a one-piece, continuous flow line, using a series of assembly station carts constructed entirely of aluminium structural framing components and systems supplied by Bosch Rexroth. Now, a finished chair comes off the assembly line every 18 minutes, packaged and ready for shipping.
In this lean manufacturing environment, a passenger seat moves through the production line from station to station, where assembly work is divided equally, so at each station exactly 18 minutes worth of work is undertaken. A passenger seat is built on a fixture that is attached to a cart, which moves down the line from station to station where the sub-assemblies, including armrests, food trays, baggage bars, in-flight entertainment systems and seat cushions are installed.
Located at each of these stations is a custom final assembly station, which is also constructed from Rexroth aluminium structural framing. This station holds a two-bin system of hardware that is used to install the sub-assemblies. It also uses Rexroth tool holders in an ergonomic, handle-first and ready-to-use position. The final stations also hold air tools hung from an overhead balancing arrangement, with air lines descending from the top of the workbench, ensuring that the tools are within easy reach of the operator. C&D’s Ryan Newman takes up the story:
“We tried shadow boards before with pegboard type wire hooks, but these proved too fidgety for operators to use. They usually cause the operator to orient the tool in an unnatural position before they place it on the shadow board, and the same situation occurs when operators are retrieving tools. The Rexroth tool rack presents the hand tools in a natural, handle-first manner, and, because it is modular, it is easy to add or remove tools at a later date.”
Before converting its production line into a ‘one piece flow’ system, C&D employed the ‘batch and queue’ method, as Mr Newman explains:
“When we used batch and queue, we had mountains of sub-assembly parts everywhere on carts and shelves, but we would never seem to have the actual parts we needed. We would build all of the seats up to a certain point and store them on the floor waiting for the next step. All of the work-in-progress seats occupied limited floor space and were not producing any profit. And, while the seats waited for a next step or parts, they were susceptible to damage as workers and equipment were forced to move around them.”
Since conversion to the continuous flow line using the carts, C&D now has only eight or nine work-in-progress chairs that are all actually being worked on, instead of just waiting for the next step that might be a day away. Overall, conversion to the continuous flow line has led to nearly a 200 percent increase in production. Mr Newman believes the aluminium framing played no small part in this success story:
“When we decided to convert the line, we chose Rexroth aluminium framing because of its ease of construction, its vast flexibility, and its fit and finish. There is no welding or painting involved, so it greatly simplifies and speeds up construction to keep production moving. Because everything is bolted together, we have the ability to make adjustments or add more features as the needs of the line change. Rexroth aluminium framing gives me the confidence that I have the flexibility to make my designs work. And, when I’m all done, I have equipment that is custom built for my exact needs, and it looks stunning and very professional.”
The large variety of aluminum framing sizes and shapes offered C & D the reconfigurable design that Mr Newham was looking for. Die-cast gusset connectors ensure the product’s flexibility, and the connections are available anywhere along the T-slot. Alignment tabs also aid assembly, as does the drop-in, T-bolt design. C&D also used adjustable angle gusset kits, which allow quick adjustment to any angle; this facilitates quick angular adjustment of shelves on a workbench, workstation, or cart.
According to Mr Newham, the actual construction of the line took about two months, while the entire process of converting to one-piece flow with all the parts, time studies, and mapped processes was carried out over a year.
“Our Rexroth project engineers have been very helpful in giving us complete solutions so that we could build our one piece flow line. And they are always visiting, and working with us to find the best answers,” Mr Newham concludes.
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