The product my company makes is similar to a residential circuit breaker box, but a bit larger and designed for industrial/commercial use. There are several product lines, but the basic assembly procedures are consistent. Small metal connector plates and other small parts are fastened to the “guts” (chassis) of the box with screws. Screws and parts are in bins, at chest height and in front of the operators. Operators use one of several pneumatic drivers in the assembly process–different drivers for different types/sizes of screws. All drivers are pulse-type tools and are maintained by individuals trained by the tool manufacturer.
Due to an upcoming facility consolidation, we have an opportunity to address line balancing and some of the ergonomic concerns we know exist. One of the unanswered questions is maximum repetitions. We would like to achieve an objective value for the maximum number of screws an operator can drive per shift. Part of the consolidation planning is looking at areas where job functions can be combined to reduce headcount.
The assembly supervisor has been around for many years, and he has come up with an arbitrary figure of 3000 screws. In his experience, when operators drive more than 3000 screws per shift he has a higher number of MSD-type complaints from his employees. However, this type of statement will not be enough to satisfy management in their effort to establish a standard protocol in assembly line job design.
I would appreciate any feedback provided and would especially like to know about any existing publications or other tools that address this issue.
When (because of the number of MSD complaints) I was asked to look at a similar operation (although number of screws fitted was not critical – only about 1600 being fitted per day), I found the major MSD problems to be related to an abducted and/or elevated arm when operating the pneumatic driver. Of course, this would depend on the design of your drivers but the ones I saw were so-called ‘ergonomically designed’.
It wasn’t entirely the fault of the driver, but more to do with the bench height (seated worker) and orientation of the box/chassis into which the smaller units were being fitted (the worker also had to lean forward to see what she was doing). A relatively simple rearrangement of her workstation, seat height and the provision of an adjustable angle flatbed jig removed (or at least reduced) many of the problems.
Viewing 2 posts - 1 through 2 (of 2 total)
The forum ‘General Ergonomics Topics’ is closed to new topics and replies.