When using diamond stone-cutting circular saw blades for the sawing of mineral materials, workers are generally exposed to high noise levels, with sound pressure levels reaching 105 dB(A) or higher. Since the circular saw blades used are the primary source of the noise, it should be possible for the noise exposure to be reduced considerably by the use of low-noise saw blades. Low-noise circular saw blades are now available from a number of manufacturers. A range of design types are available. Sandwich circular saw blades for example comprise two sheet-metal layers enclosing a viscoelastic layer. Saw blades exist with a multi-layer reinforced flange, and also with laser incisions. The reductions in sound level that can be achieved by these different saw-blade designs were to be studied in a project. The results were to be used to update an older noise protection information leaflet (LSA 02-375).
Manufacturers and suppliers of low-noise diamond circular saw blades were identified by a market survey. In order to reduce the work entailed, only saw blades with a diameter of 350 mm were studied in the first instance, as was the case in the first study performed in 2007. Following selection of a total of 19 circular saw blades of different design, measurements were performed with these blades on a stationary saw (bridge saw) during the wet cutting of granite, concrete and sandstone. In addition, nine circular saw blades with a diameter of 230 mm were studied on an angle grinder during the dry cutting of concrete paving stones.
On the stationary saw, sound pressure levels of 105 to 107 dB(A) were measured with the standard 350 mm diameter saw blades, for example during the cutting of concrete. This noise exposure was reduced correspondingly by 8 to 14 dB(A) by the use of sandwich saw blades. The mean noise reduction achieved was approximately 10 dB(A). The laser saw blades studied were only around one to three dB(A) quieter than the standard circular saw blades during cutting of the majority of materials. One particular laser circular saw blade employing a special polymer filling of the laser incisions did however yield a greater noise reduction, of approximately six dB(A). The saw blades studied with reinforced flange yielded abatements in noise levels of approximately three to seven dB(A) where the saw blades were punched. Sound pressure levels of 106 to 108 dB(A) were measured during the use of standard circular saw blades (diameter 230 mm) on the angle grinders studied for the cutting of concrete paving stones. Exposure levels were reduced by approximately seven to eight dB(A) by the use of circular saw blades of sandwich construction. Level reductions of approximately 3 dB(A) were measured for the three circular saw blades studied with reinforced flange. When these saw blades were used on the angle grinder, no notable differences in sound level were observed between the punched and non-punched variants. Since the purchase costs of low-noise diamond circular saw blades differ only marginally from those of their conventional equivalents, it can be assumed that use of the former entails no significant additional costs. A new IFA noise protection information leaflet (LSA 02-375) was prepared for presentation of the results.
construction industryType of hazard:
noise, prevention, equipment safetyDescription, key words:
sawing, mineral materials, noise exposure, circular saw blades