Air contaminants generated during laser processing of organic materials and protective measures

As compared to other thermal processes, during laser material processing of organic materials gaseous and particulate emissions are generated. Characteristic for laser-generated air contaminants (LGAC’s) is the large number of components, the chemical complexity and the varying emission rates. The characteristics and hazards of these LGAC’s must be well-known, in order to take adequate protection measures to ensure a safe laser workplace and to achieve a high environmental compatibility. Within research projects and the framework of the European project Eurolaser: EU 643 “Safety in the Industrial Applications of Lasers”, emissions have been characterized and medically assessed. Studies show that the quantity, the composition and the chemical complexity of the LGAC’s are highly dependent on the laser application, the process parameters and the material processed. Generally, the particles generated are very small and therefore can be mainly respirated. For some plastics, like Polyamides, the fume particles are viscous and can easily stick together. The gaseous hydrocarbon emissions usually consist of substances referring to the chemical structure of the material machined, often, the monomers. Aromatic hydrocarbons and polycyclic aromatic hydrocarbons are detected in all cases. Investigations on filter systems show that non-adhesive particles can be filtered efficiently with self cleaning surface filters; sticky particles, however, cause high pressure loss in the filter and the capture efficiency will rapidly drop. For organic gaseous emissions, no standard filter solution is available. In general, adsorption techniques, catalytic combustion or biological filtration can be used.