Innovative method for local hardening

The Belgian company Niko based in Sint-Niklaas and renowned for its high quality lighting switches and wall sockets gave one of its injection moulding nozzles to be used as a case study for the 'Precision Manufacturing for new and better products' joint research project.

Managed by Sirris, the 'Precision Manufacturing for new and better products' project involves a number of research institutions, universities and companies intent on making a leap in knowledge and understanding concerning precision processing, while specifically employing industrial case studies.

The injection moulding nozzles at Niko are used for injecting fibre filled plastics and are subject to wear, which affects both the life span of the nozzles and the processing properties. Within the scope of the joint research, Jan Bouquet from the PMA department at KU Leuven developed an innovative system making it possible for the steel nozzles to be milled and hardened in the same machine while clamping them in an integrated laser hardening system.

Test pieces on which various machine and laser parameters were tested for integrated hardening

The laser head is connected to a laser source via a glass fibre and fitted to a standard HSK-63 tool holder with a small piece of extra hardware that joins the CNC to the laser controls. This makes it possible to apply the laser hardening stage without having to remove the milled item from the machine, thereby resulting in substantial savings being made in both time and money. Nozzle hardness measurements also indicate that the integrated laser hardener can raise local hardness levels from 200 HV to 800 HV in just a few minutes.

Thanks to the increased hardness levels, it is anticipated that the nozzles will last longer and keep their geometrical properties more accurately - and all this without the high extra costs normally associated with complete hardening of the item. The hardness levels feasible with this technology are also up to 30% higher than when compared with conventional technologies.

(photo above: integrated laser head on HSK-63 tool holder)

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