Research on in situ monitoring of selective laser melting: a state of the art review

As an additive manufacturing technology, selective laser melting (SLM) can form any complex metal parts, which has unparalleled advantages compared to traditional processing methods. However, there are still some problems such as accuracy and non-repeatability to overcome to apply SLM to production practice. The high-precision monitoring and degradation feedback technology of SLM equipment is the future development direction. The real-time monitoring machine can repair itself and avoid the tedious detection in the post-processing stage. The researchers mainly monitor the quality of the forming process by molten pool signal, temperature signal, sound signal, and scanning track. The forming process is monitored using coaxial detection or paraxial detection through a high-speed camera, pyrometer, and other equipment. This paper can provide theoretical support for the SLM intelligent monitoring field.