ABSTRACT
Automotive assembly operations require power tools to secure fasteners and these operations have been linked to increased risk of musculoskeletal disorders. This work was designed to develop physical capability limits for direct current right-angle power tool (RAPT) operations using psychophysics. Forty females fastened joints of different hardness's using three fastening strategies, at three fastening frequencies. Participants chose to fasten, independent of orientation, joints up to 89 (10.6) Nm using Atlas Copco's TurboTight®, compared to 51.8 (8.1) Nm using Atlas Copco's Quickstep and 48.6 (10.2) Nm using Stanley's Automatic Tightening Control. The differences between fastening strategies were not as large when fastening soft joints; 59.2 (16.2), 52.3 (14.6), and 53.5 (11.3) Nm, respectively. As fastening frequency increased, participants chose lower target torque magnitudes to fasten. Based on this work, RAPT manufactures can adjust fastening strategies to improve their tool's ergonomics performance. Practitioner summary: Fastening tasks was identified as posing an injury risk to workers performing automotive assembly, yet presently there are no published physical capability limits for direct current right-angle power tool operation. Using a psychophysical methodology, physical capability limits for RAPT fastenings were established for different joint hardness, fastening frequencies and RAPT position/orientation.
ABSTRACT
Right-angle power-tools (RAPT) employed in automotive manufacturing promote greater productivity and quality fastenings, as well as, improve process efficiency. Due to RAPT technological advances automotive manufactures desire to understand their ergonomics consequences within a laboratory environment, however, laboratory-based representation must accurately represent the real world. A survey within automotive assembly plants was conducted to capture RAPT operation data. After examining 80 total RAPT operations, we logged the 3D locations of the fastener location (with respect to the operator), direction and the hand placement location used by operators. Four common locations with respect to the midpoint between the ankle (in cm; X = sagittal plane, Y = transverse plane, Z = coronal plane): 1) 2, 113, 62; 2) 42, 104, 45; 3) -26, 151, 36; 4) -37, 92, 52. These locations can be used to simulate RAPT operations within a laboratory. The survey provided insight into current workstation layout when operating RAPTs and, knowledge for laboratory-based RAPT examinations so that simulated tasks best represent their operation in automotive manufacturing.
Subject(s)
Tool Use Behavior , Canada , Ergonomics , HumansABSTRACT
The amino acid neurotransmitters gamma-aminobutyric acid (GABA) and glutamate have been implicated in mood disorders and high performance liquid chromatography (HPLC) is an important method in their quantitation. This paper describes a method which employs either electrochemical or fluorescent detection of the amino acid derivatives formed by a reaction with naphthalene-2,3-dicarboxaldehyde (NDA) in the presence of cyanide ions. Elution is based on an isocratic protocol and is achieved in 20 min or less. The method is reproducible, shows excellent linearity and generates derivatives which are stable for up to 16 h. Successful application of the method to a maternal deprivation study has identified the hippocampus and the brainstem as possible sites of long-term alteration in this paradigm.
