Layer thickness controlling in Direct Energy Deposition process by adjusting the powder flow rate

Abstract

Additive manufacturing by direct energy deposition is highly suitable to manufacture metal structures of nearly arbitrary geometry by locally melting powder or wire in a layer-by-layer manner. The layer thickness varies throughout the process due to uncontrollable and dynamic influences. The implementation of process control can be used to ensure a more constant layer thickness. Hence, target component height is achieved more precisely. This paper presents an approach to control the layer thickness by varying the powder flow rate of the powder feeder. A thermographic camera was used to measure the current structure height during manufacturing. The powder flow rate was adjusted by a PID controller operating layer-by-layer or in an alterable frequency. Different PID parameters were compared based on the manufacturing process of a wall, a cuboid, and a cross-shaped structure. As a result, a more precise match between manufactured component height and target component height was achieved.