Ergonomic interventions for the furniture manufacturing industry. Part I -- Lift assist devices

Abstract

The objectives of this intervention research project were to develop and evaluate engineering controls for the reduction of low back injury risk in workers in the furniture manufacturing industry. An analysis of injury/illness records and survey data identified upholsterers and workers in the machine room as two occupations within the industry at elevated risk for low back injury. A detailed ergonomic evaluation of the activities performed by these workers was then performed and the high risk subtasks were identified. The analysis for upholsterers revealed: (1) high forces during the loading and unloading of the furniture to and from the upholstery bucks, (2) static awkward postures (extreme flexion > 501; lateral bending > 201; twisting > 201) during the upholstering of the furniture, and (3) repetitive bending and twisting throughout the operation. For machine room workers, this ergonomic evaluation revealed repetitive bending and twisting (up to 5 lifts/min and sagittal flexion > 801; lateral bending > 151; twisting > 451) when getting wooden components from or moving them to the shop carts that are used to transport these materials. Engineering interventions were then developed and evaluated in the laboratory to document the reduction of exposure to these stressors. The height-adjustable upholstery buck system eliminated the lifting and lowering requirements and affected trunk kinematics during the upholstery operation by reducing peak sagittal angles by up to 79% (average: 52%; range: 27–79%), peak sagittal accelerations by up to 42% (average: 71%; range: 0–74%) and peak lateral position by up to 31% (average: 20%; range: 12–31%), and showed no impact on time to complete the task. The machine room lift reduced peak sagittal angle by up to 90% (average: 76%; range: 64–90%), peak sagittal accelerations by up to 86% (average: 72%; range: 59–86%) and had a positive impact on the time to complete the task (average reduction: 19%).