Search

The problem of joining the ITER VV sectors, considering the tolerance requirements of the blanket attachments, and the time required for TIG welding, continues to stimulate EU R&D into power beam welding techniques for fewer passes and lower distortion by a factor of up to 5. The work on reduced pressure e-beam welding showed that penetration varied with position, fit-up, distance and pressure and single-pass weld control seemed impractical so work on a combination of rest-current-control root weld followed by wire-fill passes promises a practical solution. The NdYAG laser welding has yielded useful and stable results and demonstrated the possibilities of improved performance over TIG. Design on the welding robot has been simulated by the successful use of computational virtual modeling techniques. A robust, singularity-free, hydraulic, parallel-configuration robot is under construction to demonstrate welding and control scenarios and the possibility of active suppression of vibrations induced by machining forces.

The pressure on manufactures in electronic industries to produce smaller components with high quality is driving the introduction of laser systems into the fabrication process. This paper outlines the state of the art in laser micro machining and in precision microfabrication. The project is being carried out dealing with industrial needs and potential applications for laser precision microfabrication in the Finnish electronics industry. In connection with the project investments in laser equipment were prepared. International contacts and relations were created for the forthcoming co-operation.

Narrow gap multirun welding tests were carried out on thick specimens (14-35 mm) of AISI 316L austenitic stainless steel (0.017%C, 1.2%Mn, 17.2%Cr, 12.4%Ni, 2.59%Mo) using filler wire (max. 0.025%C, 0.8%Si, 1.8%Mn, 19%Cr, 12%Ni, 2.7%Mo) to define a suitable welding procedure. Different V-preparation geometries and filler wire parameters were used. Cross-sections of the welds were examined to determine defects. The microstructure and hardness were also studied.