Machine safety design: An approach fulfilling European safety requirements: Dissertation

Deficiencies in ergonomics and safety cause negative consequences for companies, national economy and individuals and therefore safer and more healthy products and work environments are required. Improvements in ergonomics and the safety of existing workplaces increase job satisfaction, decrease absenteeism and accidents in companies and may also have positive effects on the quality of the products of companies. Hazard analysis and risk assessment are widely accepted in product and process design. In the European Union legislators have shifted away from the application of detailed safety requirements towards requirements for application of risk analysis by companies themselves. Manufacturers or their representatives must carry out risk assessment and take results into account in machine design (Directive 98/37/EC). The new regulations are harmonised machine safety requirements within the EU member states and make it possible to market machines throughout the EU. Today, when the revision of the directive is being considered, it is essential to integrate current safety design procedures into systematic machine design processes in order to ensure both an acceptable level of safety in machines and feasible design efforts. This work was carried out in order to integrate European safety requirements into the systematic machine design process. At the beginning of the work, the theoretical framework was described and the first version of the approach was developed. The preliminary approach was tested and further developed in case studies. The case studies cover the redesign of two existing single machines, the design of a large materials handling system and the safety design of a new single machine. The main benefit of the approach fulfilling the European safety requirements was the clarification of the safety design requirements and simultaneous safety design together with other design tasks. The results also indicated that the harmonised C-level standards do not necessarily cover all the essential safety problems related to the machine to be designed and therefore risk assessment is recommended even if the C-level standard is available. In addition, the risk estimation according to EN 954-1 (1997) was unreliable. Individual judgements regarding the severity of consequences and the possibility of a user to avoid accident varied drastically. Finally, the machinery safety directive (Directive 98/37/EC) mixes hazards, technical requirements and safety goals in a confusing manner. Therefore, the proposal for a new draft of the directive on machinery (Proposal for... 1998) should be changed in a such way that it clearly separates the hazards, the technical requirements and the safety goals.