Tolerances have to be consistently tight when you''re assembling wire harnesses for a jet fighter -- 1/8 of an inch over 32 feet to be exact. An assembly workstation that can''t accommodate such tolerances would be, well, intolerable.
That''s one problem faced by a jet aircraft manufacturer when it determined that it needed to upgrade a wire harness assembly facility. Another problem was the ergonomic failings of the old system: the facility was using pieces of plywood on wooden A-frames as the takeoff point for assembly of its 32 ft long, extremely elaborate wire harnesses with 150 termination points. This not only affected tolerance levels but also led to potential technician stress, strain, and fatigue.
With no adjustable worksurface height and no ability to adjust the tilt of the surface, technicians might have to reach as far as 6 ft to access a section of the harness. Clearly this company needed to land a new solution.
Harnessing An Ergonomically Sound Solution
The jet fighter manufacturer found a company that could deliver exactly what it was looking for in Pro-Line of Haverhill, MA, a company recognized as a leader in modular ergonomic workstations. A company renowned not just for its rugged, technologically advanced workstations, but also for its ability to "think on the fly" and produce custom, application-specific solutions, Pro-Line delivered 32 custom Electric Wire Harness Workstations, each retrofitted with a range of accessories. Pro-Line modified its existing technology with new technologies to produce a solution that was ergonomically sound, provided maximum functionality, and met all of the jet manufacturer''s specs.
The Wire Harness stations were each 4 ft deep by 8 ft wide, with a 16 in. range of height adjustability and an 80 deg tilt range. As the wire harness being assembled was 32 ft in length, Pro-Line needed to draw up a unique solution, producing eight stations comprised of four units, linked together end-to-end, in order to properly address the large job. The benches would have to move in unison, up and down, so precise tolerances were even more essential. Pro-Line was the only company among all of the contenders considered by the jet manufacturer that could deliver 1/8 in. tolerances over the entire length of the wire harness, from one individual workstation to the next. Pro-Line was also able to synchronize the individual motors to accommodate unified actuation.
Each four-unit workstation functions with one bench serving as a "master," and the others functioning as slaves. The bench designated as "master" is home to a relay switch operated by a lockout key. If, through human error, two benches are designated as "masters," the entire system will shut off.
Thanks to the range of easy vertical movement provided by the Pro-Line system, along with the 80 deg tilt, all sections of the wire harness are always within easy reach, either at or below eye-level.
A New Level of Functionality
Each Pro-Line workstation was retrofitted with accessories specifically designed for the unique needs of the assembly technicians. For example, a suspended tool trolley, which was attached to two uprights and strategically placed over the worksurface, featured tool balancers for optimal operator comfort. These spring-loaded tool balancers take on most of the weight of the technicians'' hand tools -- the weight is on the balancer and not on the hand, so fatigue is greatly reduced.
Air-quick disconnects, custom mounted inside the front rail of the station for pneumatic tools, are also within easy reach above the worksurface. Yet they were designed by Pro-Line to never extend beyond the overhead frames, so they never obstruct operator performance. All of the workstation accessories, in fact, have been strategically positioned to maximize productivity and maintain proper ergonomics. Other retrofitted accessories include overhead lighting that eliminates eye strain while clarifying every task, and power supplies for electric tools designed to keep electrical cords from interfering with work.
Since this initial installation, the jet plane manufacturer has added new accessories to its workstation system, and is currently in the process of expanding its operation with additional Pro-Line workstations. Clearly it is more than satisfied to have harnessed such precise, ergonomically sound, and productivity-enhancing workstation solutions.