Industrialization of Directed Energy Deposition process lies on the development and implementation of a Quality Assurance system that makes the process reliable and repetitive. One of the geometrical characteristics that needs constant monitoring and control during any DED process is the deposited layer height. In this paper, a multi-directional layer height monitoring system relying on laser triangulation principle that has been developed for real-time direct measurement, in contrast to majority of the sensor systems that derive layer height based on melt pool temperature, is presented.  Existing commercial laser triangulation systems are uni-directional thereby hindering the flexibility of the material handling system,  like industrial robot, in most of the cases. An additional challenge lies in the integration of sensor with the deposition head due to its form, size and extreme working conditions.

 

Therefore, a novel configuration of laser triangulation sensors that enable multi-directionality and limit shadowing effect has been developed in-house. In this paper, the mechanical design and development of such a sensor has been presented which creates a rectangular laser projection around the melt pool to enable measurement in all directions. The designed optical bench and the sensor housing has been additively manufactured through Laser Beam Melting process. This enabled the integration of opto-mechanical elements, cooling channels and cross jet in a compact cylindrical form that can be mounted radially around the deposition head. Integrated cooling channels enables operation at high temperature and harsh environmental conditions close to build zone. The developed sensor has been tested for powder based Laser Metal Deposition process.

 

In-process layer height measurement and control is possible with this sensor, thereby enabling digitalization and quality assurance during the build process. 3D point cloud generated using this sensor can be used for dimensional deviation measurement and also for downstream processes like machining. Such an in-process quality measurement and assurance system negates a post measurement step, thereby saving cost and time, and ensuring quality.