Publikationsserver der RWTH Aachen University
Electrical Discharge Machining: exposure assessment using emission and immission based monitoring
Abstract
dc:descriptionIn Germany, about 8000 sinking- and 6000 wire cutting-machines are in use, which shows the high acceptance of this concept as an industrial manufacturing process. Its benefits, compared to conventional processes, like milling and grinding, lie in the machining of materials with high hardness and strength as hardened steel tungsten carbide or conductive. There are several environmental aspects that are influenced by EDM. Health of machine operators can be attacked by exposure to chemicals that arise during the process and are set free to air, dielectric and slurry. This investigation’s main objective is the establishment of an instrument for assessing the exposure of machine operators of the sinking process of electrical discharge machining, a hazard valuating concept. The assessment of exposure will therefore provide opportunities to map the hazards of a specific EDM manufacturing process in an industrial plant, by using data from emission-based measurements as input. During this project, an encased structure around an EDM installation is used for emission based monitoring and measurements in an industrial environment are performed (immission based monitoring). The calculation of emission quantities to immission quantities using a simplified scenario shows the importance of metal emissions and emissions of aliphatic compounds, whose limit values will be exceeded after relative short production times. The concentrations of PAH and volatile organic compounds are present in very low, not significant quantities. The immission based measurements support this emission estimation scenario. The investigations have shown that the experimental model, that captures total emission of the electrical discharge machine, and is not solely based on immission values, have lead to a better understanding of the production process. This information can be used to extract recommendations regarding protection measures and monitoring aspects. Regarding the present investigation, the following recommendations are noted; 1. The parameters that are subject to investigation have to be directed to the specific EDM technical adjustments. This is particularly valid for the emissions of metals (like chromium), that have high toxicological relevance, and that are highly dependent on the metals used as work-piece and tool during electrical discharge machining; 2. During routine monitoring, the total manufacturing process and the local environment have to be paid attention to. During informal meetings with manufacturers, the information was given that next to inhalation exposure to emissions, dermatological problems have appeared. Direct contact with dielectric and slurry has probably been the main cause of these problems; 3. The need for, and the type of end-of-pipe measures has to be an individual recommendation and depends on the process, location, etc; 4. The hazard reducing measures should not solely focus on end-of-pipe measures like recommendations and instructions. During routine manufacturing these instructions are not applied most of the time. A combination with a (or more) source related technical measures, like change in technical adjustments (current, dielectric level, workpiece and tool), cleaning/changing dielectric, has higher hazard reducing potential; 5. Contact with dielectric (air borne or direct) may lead to allergic reactions (mostly skin). Operators that show these problems have to consult a practitioner and an occupational medicine man. Further activities should not only be focussed on the treatment of the operator but also on prevention by inspection and optimization of the manufacturing process in the specific plant.
Degree
thesis:*- Grantor dc:publisher
- Publikationsserver der RWTH Aachen University
- Year dc:date
- 2003
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Evertz, Sven
- Contributors dc:contributor
-
- Dott, Wolfgang
Subjects
dc:subject × 8Rights
dc:rights- Statement dc:rights
-
- info:eu-repo/semantics/openAccess
- Language dc:language
- eng
Identifiers
dc:identifier.*- OAI identifier oai:identifier
- oai:publications.rwth-aachen.de:58706