On-the-hand measurement methods for assessing effectiveness of anti-vibration gloves

Abstract

Several technical difficulties have been associated with the current test and evaluation methods for assessing the vibration isolation effectiveness of anti-vibration gloves. The effectiveness of the gloves for specific powered hand tools can be assessed through measurement of acceleration on the head of the third metacarpal or at the wrist. In the present study, the reliability of these on-the-hand measurement methods is evaluated through assessing the vibration transmissibility of gloves while operating chipping hammers. Two different methods, with and without the prior knowledge of tool vibration, for deriving the transmissibility of the gloves are also evaluated. The study used an air bladder glove and a gel-filled glove, two chipping hammers, and feed forces in the 50–200 N range. Six male volunteers were used as test subjects. The transmissibility of the gloves is also estimated using a total vibration transfer function method. The results suggest that the on-the-hand methods offer some unique advantages over the palm adapter method outlined in ISO-10819, but they suffer from poor repeatability when a high degree of tool vibration variability is observed, especially if the tool vibration is not measured and used for the assessment. Glove transmissibility measured at the third metacarpal is more repeatable than that derived from the measurements at the wrist. Reasonably good agreements were observed between the predicted and measured transmissibility values of the air glove. However, the measured transmissibility values for the gel-filled glove suggest that it may perform better than as predicted using the transfer function method. Relevance to industry Prolonged exposure to hand-transmitted vibration has been related to an array of health disorders of the vascular, nervous and musculoskeletal systems in the upper extremity. Anti-vibration gloves can be used to help reduce the severity of vibration exposure. The current glove assessment methods exhibit several technical difficulties and do not provide information regarding the effectiveness of the gloves when used with specific power tools. This study examines the effectiveness of on-the-hand measurement methods and the transfer function-based prediction method to determine more reliable glove assessment methods. The study also proposes a test device and method for assessing the vibration effectiveness of gloves when used with pneumatic hammers. It is anticipated that the proposed glove assessment method would be applicable to other types of hand-held power tools.