title: Predicting tool operator capacity to react against torque within acceptable handle deflection limits in automotive assembly.
abstract: The proportion of tool operators capable of maintaining published psychophysically derived threaded fastener tool handle deflection limits were predicted using a biodynamic tool operator model, interacting with the tool, task and workstation. Tool parameters, including geometry, speed and torque were obtained from the specifications for 35 tools used in an auto assembly plant. Tool mass moments of inertia were measured for these tools using a novel device that engages the tool in a rotating system of known inertia. Task parameters, including fastener target torque and joint properties (soft, medium or hard), were ascertained from the vehicle design specifications. Workstation parameters, including vertical and horizontal distances from the operator were measured using a laser rangefinder for 69 tool installations in the plant. These parameters were entered into the model and tool handle deflection was predicted for each job. While handle deflection for most jobs did not exceed the capacity of 75% females and 99% males, six jobs exceeded the deflection criterion. Those tool installations were examined and modifications in tool speed and operator position improved those jobs within the deflection limits, as predicted by the model. We conclude that biodynamic tool operator models may be useful for identifying stressful tool installations and interventions that bring them within the capacity of most operators.
authors: University of Wisconsin-Madison, 1550 Engineering Drive, Madison, WI 53597, USA. Electronic address: radwin@engr.wisc.edu.
authors: Robert G
authors: RG
authors: Radwin
authors: University of Wisconsin-Madison, 1550 Engineering Drive, Madison, WI 53597, USA.
authors: Amrish
authors: A
authors: Chourasia
authors: University of Wisconsin-Madison, 1550 Engineering Drive, Madison, WI 53597, USA.
authors: Frank J
authors: FJ
authors: Fronczak
authors: University of Wisconsin-Madison, 1550 Engineering Drive, Madison, WI 53597, USA.
authors: Yashpal
authors: Y
authors: Subedi
authors: University of Wisconsin-Madison, 1550 Engineering Drive, Madison, WI 53597, USA.
authors: Robert
authors: R
authors: Howery
authors: University of Wisconsin-Madison, 1550 Engineering Drive, Madison, WI 53597, USA.
authors: Thomas Y
authors: TY
authors: Yen
authors: University of Wisconsin-Madison, 1550 Engineering Drive, Madison, WI 53597, USA.
authors: Mary E
authors: ME
authors: Sesto
authors: University of Wisconsin-Madison, 1550 Engineering Drive, Madison, WI 53597, USA.
authors: Curtis B
authors: CB
authors: Irwin
mesh_terms: D000328:Adult; D001336:Automobiles; D001696:Biomechanical Phenomena; D004867:Equipment Design; D006804:Ergonomics; D005260:Female; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D066192:Manufacturing Industry / Q000295:instrumentation*; D008962:Models, Theoretical; D011930:Reaction Time; D013647:Task Performance and Analysis; D019415:Torque; D014938:Work Capacity Evaluation; D017132:Workplace
keywords: Dynamic strength; Nutrunner; Power hand tool; Tool operator biodynamic model; Upper limb biomechanics; Work related musculoskeletal disorders