THERMO-MECHANICAL CRACKING OF A NEW AND LASER REPAIR WELDED DIE CASTING DIE

The paper presents the analysis of thermo-mechanical fatigue cracking of die casting die during industrial use. An innovative, production friendly approach to monitor the surface crack dimensions was introduced, which is based on measuring defect-fin on the casting part. A new four moulds die casting die was monitored 40 000 cycles in order to complete the production series. The production was stopped three times for laser repair welding of cracks since the defect-fins were not acceptable. The defect-fin heights were measured every 1 000 cycles on the castings before and after repair welding of die surface cracks. The in-service die life can be prolonged with laser repair welding for several times, even thought that in-service die life for a particular repair varies.