An Investigation of the Effects of Drill Operator Posture on Vibration Exposure and Temporary Threshold Shift of Vibrotactile Perception Threshold

Mark Taylor,Setsuo Maeda,Kazuhisa Miyashita

doi:10.3390/vibration4020025

Mark Taylor, Setsuo Maeda + Show 1 more

Open Access

https://doi.org/10.3390/vibration4020025

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Abstract

The present study involved performing an experiment to clarify whether vibration measurement values on the tool handle, in accordance with ISO 5349-1, can assess risk from workplace environments. The study investigated the relationship between the vibration magnitude of a hand-held electric drill with different operating postures. The experiment included the determination of the participant’s temporary threshold shift (TTS) of vibrotactile perception threshold (VPT) at the tip of the index finger. The experimental hypothesis was that the vibration measurement values on the tool handle, in accordance with the ISO 5349-1 standard, include the effect of posture on the vibration measurements obtained despite the variation in posture and test participants. The hand-transmitted vibration (HTV) was applied using a hand-held electric drill applied to a pre-cast concrete paving slab substrate (600 × 600 × 50 mm, 55 MPa) using a 10 mm diameter masonry drill bit (without hammer action). The tool was operated using the right hand on twelve male subjects with three working postures (n = 36). Vibration was measured in three orthogonal directions according to the international standard ISO 5349-1 procedure. Vibration magnitudes were expressed as root-mean-square (r.m.s.) acceleration, frequency-weighted using the Wh frequency weighting. Clause 4.3 states that the characterisation of the vibration exposure is assessed from the acceleration of the surface in contact with the hand as the primary quantity. The experimental results indicate that the TTS following vibration exposure is not related to the measured vibration magnitude on the tool handle. Therefore, the automatic inclusion of posture and test participant variation is not proven. The results suggest that the vibration measurement values on the tool handle do not predict the TTS after hand-transmitted vibration in varying posture across the test participants. The research concludes that tool handle vibration measurement, in accordance with ISO 5349-1, does not properly assess the potential hazard from authentic workplace tool usage conditions of varying postures.

Highlights

In industrial workplace environments, operatives are exposed to hand-transmitted vibration (HTV) with a broad range of postures, tools and tool use operations being adopted
Industrial operatives are prone to a range of conditions affecting the musculoskeletal, neurological, and vascular systems collectively known as hand–arm vibration syndrome (HAVS)
The results presented contribute to the evidence that suggests that the tool vibration measurement method, according to the ISO 5349-1 and ISO 5349-2, cannot capture the hand-transmitted vibration including the many affecting factors to evaluate the exposure vibration

Summary

Introduction

Operatives are exposed to hand-transmitted vibration (HTV) with a broad range of postures, tools and tool use operations being adopted. Academic research has clarified the relationship of vibration dose and the human response to vibration and subsequent diseases that ensue [1,2,3,4]. These studies were undertaken in live working environments and reflected in-use conditions. The vibration magnitudes were expressed as root-mean-square (r.m.s.) acceleration, which was frequency-weighted and band-limited using the Wh filter in accordance with ISO 5349-1. The root-sum-of-squares (vibration total value, ahv) of the frequency-weighted acceleration values for the x, y and z axes are calculated using: ahv = (ahwx2 + ahwy2 + ahwz2)

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Discussion

Conclusion