Metal-on-metal impacts are a common and often disproportionately significant source of noise in many metal fabricating shops.
One major motor manufacturer recently installed a cropping machine to automate the finishing of castings, previously carried out by operators using hand-held pneumatic tools.
While the new equipment reduced noise exposure during the process itself, noise was still being generated by the unloading mechanism. A mechanical arm lifted the casting out of the machine, rotated it clear and then dropped it from a height of about 1 m onto a metal chute. The impact of the components onto the chute created peak A-weighted levels of 100 dB.
A 5 mm layer of wear-resistant rubber matting was applied to the inside surfaces of the chute.
About £75 per square metre for material, plus installation. (1995)
A noise reduction of about 15 dB. The treatment also protected the casting and chute from impact damage.
Information and photograph supplied by Ford Motor Company Limited.