Measurements conducted by the competent German Berufsgenossenschaft in the wood-working industry showed that the technical exposure limit (TRK-value) for wood dust at workplaces with manual wood working activities was regularly exceeded. Investigations on a test bench were intended to identify suitable measures to reduce the dust emission of hand-held machinery. The project was especially aimed to find out which emission levels could be achieved by using integrated dust extraction devices.
Test conditions were determined on the basis of EN 50144"Safety of hand-held motor operated electric tools" and DIN 33891, Part 3 "Dust emission of technical equipment; Determination of dust emission rate; Handholding saws". The following machines were chosen for the test in agreement with the umbrella organisation of the electrical engineering industry (ZVEI) and the competent Berufsgenossenschaft: hand- held circular saw , jig saw, biscuit jointer, planer, belt grinder, eccentric sander, orbital jig saw. In a first step, the dust emission of these machines was determined in a test chamber without using any suction. This was necessary to quantify the emission reduction achievable by means of dust abatement measures. The latter consisted in an integrated suction device - a turbine in the machine presses the dust into cloth or paper bags - and an external suction device, with the machine being connected to an external dust extraction device by means of a suction hose. Dust wood measurements were conducted at the following points: the chamber funnel, the workplace (operator's place), close to the chamber's entrance door and on the worker (personal sampling).
For the orbital jig saw, the eccentric sander, the belt grinder, the biscuit jointer and the jig saw the use of integrated suction devices turned to be extremely efficient even under worst- case conditions. It could be shown that the dust concentration depends largely on the quantity of chip production, the suction degree and the fineness of dust. Circular saws and planers still have to be used with an external dust extraction device. For the circular saw dust concentrations were particularly high, because of the enormous chip production and the poor capture efficiency underneath the chip board. The problem with the planers were the quickly obstructed dust collection bags. To ensure the efficiency of integrated suction devices used with hand-held wood-working machinery, the latter should be tested in accordance with DIN 33892 "Dust emission of technical equipment - Evaluation of the emission of airborne hazardous substances", Part 2 "Determination of the pollutant concentration parameter, test bench method, hand- held electrical wood working machines".
wood working industryType of hazard:
Gefahrstoffe, Arbeitsbedingte Erkrankungen, Arbeitsbedingte GesundheitsgefahrenCatchwords:
Maschinensicherheit, Prüfverfahren, NormungDescription, key words:
oak and beech wood dust, carcinogenic, wood dust concentrations at the workplace, wood-working machines with/without suction, reduction of exposure