Reduction of workers' hand-arm vibration exposure through optimal machine design: AHP methodology applied to a case study

The exposure of workers to mechanical vibrations represents a significant risk in many industrial sectors, due to the widespread presence of vibrating machines, and its assessment and reduction are actually considered a priority in the whole of the European context. The present work has a dual objective: (i) as a preliminary step, to analyse the state of the art in the field of vibratory machines and their design or selection, focusing on hand-arm vibrations; (ii) to propose a new instrument for systematic analysis that may be used by manufacturers of vibratory hand-held machines when choosing optimal technical solutions to minime vibration emissions. A general review of fixed and portable vibratory machines from different productive areas is given initially; existing methods and technical solutions for reducing their emissions at source are consequently detailed, based on International regulations, scientific literature, technical standards and guidelines. A framework based on an Analytic Hierarchy Process (AHP) multi-criteria analysis is then defined and proposed as a possible instrument for choosing anti-vibration solutions while designing hand-held machines. Finally, such procedure is applied to the real case study of an Italian company producing brush-cutters.