Effect of Frequently Using Workshop Tools on Worker's Hand Arm Vibration and Safety

Abstract

In the workshops of agricultural sector there are a lot of technical jobs which widely use hand-held or bench-top workshop power tools such as angle grinders, drills, riveters, chain saw, pneumatic hammers and torque wrenches. Which consider the most important sources of hand arm vibration (HAV) These workshop power tools are known to transmit substantial vibrations to the operators/worker's hand and arm and act as vibrations resource consequently, create problems for operators/workers who regularly exposure to hand arm vibrations. Therefore, the main objective of this investigation is to study the effect of frequently using of workshop tools on worker's hand arm vibration and safety. The study selected eight representatives healthy workers were well familiar with the workshop power tools control levers and had sufficient experience of operating some power tools from both bench-top and hand held workshop power tools (stand drill, wheel grinder, disc cutter, angle grinder impact drill, and rotary hammer drill with different spare discs under two different working postures as vertically erected and squeeze) during five different operations, namely, grinding, drilling, cutting, breaking and polishing using three types of materials (metal, wood and concrete). Parameters such as frequency-weighted vibration acceleration in root mean square (RMS), heart pulses rate (HR), blood pressure (BP), work related body pain (WRBP), stand height, arm length and mass of operators were evaluated. Vibration measurements were performed according to (ISO 5349-2: 2001). Workshops operations were conducted in a statistically designed layout (randomized complete blocks design) and were conducted at applied research farm of Rice Mechanization Center, Meet Eldeeba, Kafr El-Sheikh Governorate, in the 2018. The obtained results indicated that the cutting by the angle grinder gives the highest HAV data of the frequency weighted RMS acceleration magnitude while, the largest single orthogonal axis is in the axis (X) which exceeded than both of exposure action value and exposure limit value. This causes a high risk on the worker hand-arm which increases the heart rate and blood pressure followed by the polishing by the hand angle grinder. On the other hand, the HAV emission level recorded the lowest values during grinding by the bench-top wheel grinder and drilling by the bench-top stand drill consequently; there is no risk on the operator hand-arm and also the heart rate and blood pressure. Using rubber gloves during cutting by the hand angle grinder leads to a decrement percentages in the HAV values and so heart rate and blood pressure. The maximum WRBP values were obtained during the cutting by the angle grinder on working squeeze posture followed by cutting by the angle grinder on working normal posture and polishing by the angle grinder. Maximum pain levels of 15.6, 14.8 and 13.6 (Borg scale) were observed respectively. Results showed that there are significant differences between RMS, SBP, DSBP and heart rate during the different workshop operations.