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Evaluation of handle design characteristics in a maximum screwdriving torque task.

Authors
Kong-Y-K; Lowe-BD; Lee-SL; Krieg-EF
Source
Ergonomics 2007 Sep; 50(9):1404-1418
NIOSHTIC No.
20032530
Abstract
The purpose of this study was to evaluate the effects of screwdriver handle shape, surface material and workpiece orientation on torque performance, finger force distribution and muscle activity in a maximum screwdriving torque task. Twelve male subjects performed maximum screw-tightening exertions using screwdriver handles with three longitudinal shapes (circular, hexagonal and triangular), four lateral shapes (cylindrical, double frustum, cone and reversed double frustum) and two surfaces (rubber and plastic). The average finger force contributions to the total hand force were 28.1%, 39.3%, 26.5% and 6.2%, in order from index to little fingers; the average phalangeal segment force contributions were 47.3%, 14.0%, 20.5% and 18.1% for distal, middle, proximal and metacarpal phalanges, respectively. The plastic surface handles were associated with 15% less torque output (4.86 Nm) than the rubber coated handles (5.73 Nm). In general, the vertical workpiece orientation was associated with higher torque output (5.9 Nm) than the horizontal orientation (4.69 Nm). Analysis of handle shapes indicates that screwdrivers designed with a circular or hexagonal cross-sectional shape result in greater torque outputs (5.49 Nm, 5.57 Nm), with less total finger force (95 N, 105 N). In terms of lateral shape, reversed double frustum handles were associated with less torque output (5.23 Nm) than the double frustum (5.44 Nm) and cone (5.37 Nm) handles. Screwdriver handles designed with combinations of circular or hexagonal cross-sectional shapes with double frustum and cone lateral shapes were optimal in this study.
Keywords
Analytical-methods; Analytical-processes; Ergonomics; Musculoskeletal-system; Tools; Hand-tools
Contact
BD Lowe, National Institute for Occupational Safety and Health, Division of Applied Research and Technology, Engineering and Physical Hazards Branch, 4676 Columbia Parkway, MS C-26, Cincinnati, OH 45226
CODEN
ERGOAX
Publication Date
20070901
Document Type
Journal Article
Email Address
blowe@cdc.gov
Fiscal Year
2007
NTIS Accession No.
NTIS Price
Issue of Publication
9
ISSN
0014-0139
NIOSH Division
DART
Priority Area
Construction
Source Name
Ergonomics
State
OH
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