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F-22 Mid fuselage harness production
The F-22 'Raptor' is the US Air Force 'air dominan ce' platform for the 21st Century.
By Melissa C. Flens Lean Deployment Analyst Lockheed Martin Aeronautics Co. Ft. Worth, Texas
Why Lean? A "burning platform" existed within the electrical harness fabrication department at Lockheed Martin Aeronautics Company Fort Worth (LM Aero FW). During the Engineering and Manufacturing Development phase of the F-22 program, a decision was made to offload the fabrication of electrical harnesses for the F-22 mid-fuselage to Mexico. The Fort Worth jobs for this task were going away. The workers in the fabrication area teamed up to fight to retain the work and their jobs. The F-22 program office, whose responsibility is to provide value, affordability, and capability to the customers, the U.S. Government and the warfighter, issued a daunting challenge to the team: lower the cost. This meant reducing the labor hours it takes to build the product by 74 percent, which was by no means an easy challenge. Furthermore, there would only be one shipset of product available to demonstrate the reductions: a steep learning curve indeed. A radical departure from business as usual needed to occur at LM Aero Fort Worth, "business as usual" just wasn't going to cut it. "Lean thinking" was that departure a new paradigm of thinking. Lean focuses on value, but not just any value, customer value is the key. How could the LM Aero team show the customers that they are the best at what they do in a highly competitive market, and that the team understands they are there to provide value for the customer? The LM Aero team needed to be able to produce harnesses at a cost that could compete with harness production facilities that have historically been able to do the job cheaper.
What Is Lean? In a nutshell, Lean constitutes a philosophy of how to satisfy customers' increasing demands for greater value. Value is a measurement of the worth of a specific product or service by a customer, and is a function of: (1) the product's usefulness in satisfying a customer need, (2) the relative importance of the need being satisfied, (3) the availability of the product relative to when it is needed and (4) the cost of ownership to the customer. Lean thinking also provides a path to achieving ideal value-creation processes. An ideal value-creation process exists when the fewest number of steps are properly sequenced and made to continually flow. Achieving the "fewest number of steps" calls for waste elimination. Waste is anything that does not produce value and can be found in seven forms: too much inventory; unnecessary transport; waiting; unnecessary motion; over-processing (too many steps to complete a job); producing defects; and over-production (producing too much or too soon). To become lean, or to more efficiently produce value, you must accelerate the flow of product through an area. Flow is a key driver because it reduces inventory and storage, clarifies the processes required, and brings order to a chaotic environment.
Establishing Flow In order to define an optimum flow, the first step is to map out and understand the current-state value stream. Upon close examination, it quickly becomes obvious that steps in the process are being performed solely because "it has always been done that way" or "that is what the paperwork says to do." Tradition and paperwork have their place, and there are some things about building harnesses that just don't change, but doing something without understanding what value it brings to the process is dangerous because of the potential to breed waste.
In order to remove the waste, the group established a general plan that would help achieve flow. The decision was made to build an entirely new cell that had everything needed to build harnesses from wire-cut through the dress out process. The area would feature a one-way product flow. The first radical change tackled in order to achieve flow was to institute sub-assemblies into the building process. The driving force behind this decision was to remove task from the layout level and balance the workload while reducing the cycle time. The Layout/Board technique of production was then converted into an assembly line layout. Previous methodology would have had most of the 122 harness boards set up at all times. The new plan featured only 4 lines of production meaning that the maximum of 4 sets of boards are set up and in production at any one time. The sub-assembly workstations feeding the layout lines are also cellular in fashion. They are in an "L" shaped arrangement with the tools and parts needed for each stage of sub-assembly located in a specific location. The tasks performed in subassembly are arranged to proceed from right to left so that the employee need only to swivel slightly in their chair to produce a sub assembly.
What Lean Means to Me "This transition from conventional methods to lean methods is truly amazing, to see where we are today as compared to one year ago is heartfelt and credited to all the employees ideas. Their ability and willingness to embrace change is to be applauded. "Lean has enabled us to reduce cost and cycle times by 70 plus percent in only one build cycle, this type of dramatic change and effect on is something that has not been experienced since the facility was built. \"We saw early on I the implementation the amount of frustration that was being experienced by the workers looking for tools, when given the opportunity to establish new methods centered around eliminating waste the new tool cart ideas became the pride and joy of the worker." David Coffman,
One major challenge that had to be addressed when introducing the flow line concept was how to layout the harness only once. Previously, the harness were brought to the board several times in order to have markings placed on it after braid, cut the wire ends to the proper length, and finish off the harness and sell it. The solutions to this problem required Process Engineering to break paradigms as well. The governing process standards and work instructions had to be changed to realize the layout methodology. One solution was to mark the harnesses before braid. Now, colored tape is placed where the main harness ID is supposed to be located while the harness is still on the board. The bright orange tape is visible after braid and a new piece of orange tape can be placed in the proper location so that the ID can be shrunk in the marked location at dress out.
Priscilla McCain, Mockup Assembler, routing harnesses utilizing new process methods and assembly tilt board.
The solution described above was also used for the critical clamp markings where a piece of critical clamp tape was placed while on the board and then reapplied after braid in the correct spot. Because the employees who install the harnesses had encountered trouble in the past distinguishing between secondary IDs and Critical clamp ID, yellow transparent tape is now placed over the critical clamp ID so that they are easily distinguishable from the secondary harness IDs and the Primary harness IDs. To eliminate the need to trim the wire cut ends on the board, Engineering agreed to permit the harness builders cut the wires _" longer than marked on the drawing. Testing was done to ensure that enough room was left to allow for shrinkage and creep, and it was determined that _" was sufficient to ensure that the harness was long enough, but not too long after braid.
Additionally, custom tables were built that tilt forward and back as well as lift up and down to allow a harness to be laid out without having to walk around the board. A major reduction in walking distance was accomplished for the layout task. These tables also reduce injuries caused by leaning forward and are able to be adjusted to accommodate people of different heights.
Pull System To accompany the new schedule, a new method for loading jobs into the shop was implemented. Now, a pull system utilizing kanbans is in place for harness production. This system allows only a limited work-in-process inventory to queue up before wire cut, with jobs in the order that they will be produced. Employees now rotate around the cell in order to keep up with the new schedule. All workers are cross-trained to perform every job in the area so that when their task is complete they can move to the next available area.
In order to effectively manage the new area, when considering the importance of producing to the scheduled need of the using area and the critical cycle times established for flow, schedule boards were made that define when each harness is supposed to start the critical layout process. This board visually signals the supervisor and production employees to start a particular job at a specific time with a certain amount of people. A cell takt time (or rate of need) was determined specifying how many jobs need to be completed each day to fill the users need. That information was then translated to the layout area to determine when each job should start, and how long it should take.
Work Control Board used to manage and assign workloads in
Rapid Changeovers The harnesses (122 total with lengths of up to 32 feet) are built up on 4' x 8' boards. This results in a very large number of boards to keep organized. The boards are now stored in modified racks with Teflon coated rails. They are kept grouped by the line the job is built on and in alphanumeric order. The board racks are labeled and the boards themselves are labeled and color coded by the line. Test adapters also needed to be stored in an organized manner close to the tester. Rolling pegged carts are utilized to "kit" the adapters for the testing requirement. The adapters are stored on pegs in alphanumeric order only feet from the tester in a much smaller space. These items are now easy to locate when needed, significantly reduces set-up time and space requirements. Undoubtedly, the most time consuming operation under the old process was testing the wire cut ends with J-boxes. Individual wires had to be connected to individual alligator clips. The testing process was changed to allow bundling of the wire cut ends to be wrapped with metallic tape and the tape is hooked up to the tester with an alligator clip. This reduced the setup time for test from nearly an hour to minutes per harness.
Brenda Sauls, Mockup Assembler and IAM Union Committeeman, operating innovative wire cutter/laser marker.
Treating The Operators As Surgeons Consider a surgical suite. Everything is highly organized and visible such that surgeons and nurses do not waste valuable time searching for the items they require. The LM Aero approach is to treat the assemblers or operators as surgeons. Tools that are needed to do the job are presented in the location where the job is performed. Tools and supplies are organized so that everything is visible and searching is unnecessary. Portable work carts were designed to hold all the tools, operating supplies, and production hardware needed to build a harness. These carts have small shelves on them to hold items that are currently being used and the rest of is covered in small plastic bins that are labeled and when needed, shadowed with foam to hold the items in-place. These work carts are then assigned to a workstation rather than a person. The result is wherever an employee is working, they have everything they need. This process reduces walking, searching and general frustration that was associated with the old way of doing things.
Several other improvements have enhanced the working conditions in the area and increased productivity. One relatively simple idea was shadowboxed kits. At LM Aero FW, two different kits are built for each harness. One kit utilizes a box with foam cutouts and holds parts as well as wire. The parts and wires are sorted by sub-assembly point, which eliminates the sorting tasks, and assists when laying the points out on the board. The other kit is a plastic box that holds the production hardware in separate, labeled compartments. This system makes shortages very visible, provides visibility of the progress of the harness through assembly, and eliminates the wasteful sorting tasks.
Along with the work carts, a supply supermarket was set up in a centrally located position in the cell. This supermarket contains any supplies that may be needed to fill up the work carts or in case something was left off of the work cart, provides a central supply location.
There is no longer a need to search all over to the area to find replacement supplies, instead the assemblers know where to go and that anything they need should be found there.
Once the harness is removed from the layout board it is draped neatly on a rolling pegged cart. This cart allows the employee in the next process to visually see the entire harness and eliminates the practice of rolling the harness up which precludes possible quality issues and does not add value to the product.
Intelligent Use Of Technology Essentially, harness production involves the bundling of wires of various lengths and attaching connectors to the ends. Accordingly, the wire cut operation had to undergo many changes in order to accommodate the production schedule and flow. A wire cutting and laser-marking machine was purchased that precisely cuts the wires and numbers them quickly.
The data for each wire in a harness assembly is electronically pulled from a planning database on a network server. The machine is programmed to cut the wire to a specific length and print the sub-assembly point number on it so the wires can be sorted easily and placed in the appropriate slot in the harness kit shadow box.
Shadowboxed kit delivery systems using mobile slanted shelved 'bread racks'.
To feed the new machine as well as the manual wire cut table (utilized to cut twisted wire), specialized spool racks were installed to hold multiple spools of wire in a relatively small space and can be easily repositioned to retrieve a new wire type when needed. An overhead handling system was also setup to assist in loading the new wire racks and reduce possible injuries caused by lifting heavy wire spools. The tube and tape-printing machine was also improved to accept electronic input from the planning database, eliminating manual input.
Charlene Adams, Mockup Assembler, performing 'first end'
Delivering Better Value to the Customers To eliminate waste and deliver better value, the way people think about how work is performed needs to be changed and the new method proven better. Defining a new flow, or way of production, means nothing if the employees don't trust it and are not willing to try it. Early buy-in by the team was essential for success. Education in lean philosophies was given and the team given ownership of the re-engineering efforts.
The team was allowed to make obvious, easy changes early on with success; thus establishing trust in the change process. The electrical harness cell group has implemented the changes over a six-month period, and has nearly completed one ship set of harnesses with the changes fully implemented. The results have been staggering. The goal was a 74 percent reduction in the hours it takes to build a set of harnesses. Preliminary data suggest that the team should be very close to achieving that goal, which is especially impressive given one shipset of harnesses to accomplish the task. Other improvement metrics: operator travel distance reduced 94 percent; parts travel distance reduced 54 percent; span time reduced percent; and on-time delivery improved percent.
The results are in, lean works and benefits everyone involved in the process.
For further information on "Lean Works" contact Robert E. Boykin, Lockheed Martin Aeronautics Company, P.O. Box 748, MZ 6260, Ft. Worth, Texas. Phone: (817) 777-7791. E-mail: robert.e. boykin@lmco.com. |
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