Upholstery Bucks

Height-adjustable Upholstery Bucks

The detailed video task analysis of the upholsterer position revealed several known risk factors for low back injury. These risk factors included:

high forces during the loading and unloading of the furniture to and from the upholstery bucks (saw horses)
static awkward postures (extreme flexion > 50o, side bending >20o , twisting >20o) during the upholstering of the furniture
repetitive bending and twisting throughout the operation.

Currently, the furniture frames are on non-adjustable bucks for the duration of the upholstery process. This forces the upholsterer to work in awkward positions and use the staple gun in awkward positions. Height-adjustable bucks were developed to allow the upholsterer to position the furniture at an optimal height for each task. Two bucks are needed for each upholstery operation, one for each side of the furniture. The distance between the two bucks can be adjusted to accommodate all sizes of furniture.

The current prototype (shown above) utilizes existing upholstery carts that are commercially available. The pneumatic cylinders have been incorporated into the structure of these bucks. The overall function of the system is as follows. The upholsterer brings the un-upholstered piece to their workstation via a rolling cart. The upholsterer then slides the piece from the rolling cart onto the height-adjustable bucks. The upholsterer then uses a foot pedal that controls the airflow into the pneumatic cylinders to control the height of the bucks. When completed the upholstered piece is then slid from the bucks back onto the cart and rolled away. This system eliminates the heavy awkward lifts to and from the stationary bucks and controls the awkward and often static postures of the low back, shoulder and hand/wrist during upholstery process.

ADVANTAGES

Height-adjustable bucks allow for more neutral postures to be maintained by the worker, reducing back, neck and wrist flexion.
The bucks can be adjusted quickly so that the upholsterer can make adjustments without affecting productivity.

LABORATORY TESTING

The subject simulated the upholstery operation by pulling on fabric that was attached to the arms, back and front of a sofa frame. Subjects performed the pulls/pushes in a specified order and were instructed to pull with the non-dominant hand using a pinch grip. Subjects also held a staple gun in the dominant hand and simulated stapling with the gun, although no staples were used. The task was performed in 2 conditions. In one condition, the height of the buck remained in the lowest position. In the other condition, the height-adjustability of the upholstery bucks was utilized. While the subject performed the task, the researcher collected back movement data using the Lumbar Motion Monitor.

These pictures show the testing set-up. The right-hand picture shows that use of the height-adjustable buck reduces back flexion when working on the bottom areas of the sofa frame.

Results

The results of the laboratory evaluation of the height-adjustable bucks showed considerable reductions in the required sagittal range of motion of the torso, peak sagittal acceleration of the torso, and lateral range of motion of the torso, while maintaining (or in some cases slightly improving) productivity.

FIELD TESTING

During this evaluation, we found that the height-adjustable upholstery bucks are best for plants in which upholsterers work on a completed frame as opposed to pieces, such as arms. We also found that we needed to add more height-adjustability so that the highest height would allow workers to adopt neutral shoulder and back postures while working on the top of a furniture frame.