Laser additive manufacturing (LAM) is a layer wise fabrication technology which enables the production of complex shaped, individually designed parts with mechanical properties comparable to conventionally manufactured parts. However, the part manufacturing is relatively slow and via this whole production feasibility is not yet totally studied for real series production, as findings from literature shows. It is obvious that many of those studies are carried out in companies “behind locked doors” and because of this whole era of research is suffering of this lack of information.
Even though the throughput time from idea to real metal product is short, the throughput time of the actual LAM phase could still be improved to gain more feasible fabrication method. Due to this, it is necessary to increase the build rate in order to improve the process efficiency and also improve whole production feasibility of LAM. It was observed that there are only few public studies about process efficiency of laser additive manufacturing of stainless steel. According to literature, it is possible to improve process efficiency with use of higher laser power and thicker layer. The process efficiency improvement is possible if the effect of process parameter changes in manufactured pieces is known.
The manufacturing strategy of track by track and layer by layer involves a lot of different independent and dependent thermal cycles all having an influence on the part and material properties and this way to end result of process.
Experimental tests of this study were made with two different machines: with a modified research machine representing EOS EOSINT M-series and with an EOS EOSINT M280. Material used was stainless steel 17-4 PH.
Since the quality of manufactured parts depend strongly on each single laser-melted track and each single layer, this study concentrates to investigating the effects of the processing parameters such as scanning speed and laser power on single-track formation.
It was concluded that heat input has an important effect on the penetration depth and possibility to melt thicker powder layers. These factors were noticed to be crucial for improving process efficiency. It was concluded in single track tests that some of the tracks have very deep and narrow penetrations into the bulk material. It was also observed that there is possibility to form keyhole in each exposed track with the tested parameters. It was concluded that laser interaction time has effect on the depth of the penetration and keyhole formation, since the penetration depth is increasing while the laser interaction time increases.