1.Overview

Directed Energy Deposition (DED), one category of Additive Manufacturing (AM) technologies, has become widespread in industrial fields such as aerospace and energy. The use of DED for cladding and applying wear resistant coatings is spreading especially quickly, as the need for high hardness materials like alloy tool steel increases. DED has the ability to add new properties to surfaces of inexpensive base materials in whole or only in targeted areas. Moreover, DED can often be applied to workpieces and parts, which were not specifically designed with additive manufacturing in mind. Therefore, the manufacturing- cost, waste, and energy consumption, as well as the resulting amount of CO₂ emitted can be reduced by DED. In this way, DED is also drawing attention as a vehicle to social goals such as reducing the environmental impact of manufacturing. Based on this background, we developed our DED implementation as a hybrid metal-working AM machine, where DED is integrated into a five-axis mill-turn base. (Fig.1).

Fig.1 Hybrid metal AM machine LASERTEC 3000

2.Technology

As shown in Fig.2, in this machine, the AM head is attached to a tool spindle, so DED can be performed in addition to turning and milling. In DED, powder is dispensed under a shield gas unto the workpiece surface, which a laser melts. DED enables not only the creation of parts from scratch, but also coating and hardening of preexisting ones. This hybrid of technologies cuts down on setup time, by integrating multiple processes such as additive, subtractive, hardening and finishing into a single one.

Fig.2 Inside of machine (Left) and DED principle (Right).

conventionally require dedicated machines into one machine, thus, The amount of CO₂ emission generated especially in the hardening process and setup time can be dramatically reduced. Figure 3 shows an example of process integration this technology unlocks. In manufacturing of gears the required steps of turning, hobbing, finishing, chamfering, heat treating and griding can be completed in one machine, with a single setup step. Energy consumption is estimated to be cut in half by process integration this deep.

Fig.3. Example of process integration with gear manufacturing

In addition, we developed and integrated a process monitoring system shown in Fig.4 to realize stable, reproducible, and high-quality deposition. In this system, parameters which are known to influence deposition quality, such as melt pool- temperature and size, distance between laser nozzle and workpiece, substrate temperature, powder- and gas flow are monitored in real time. These process parameters are adjusted automatically, keeping melt pool size and temperature in a specific desired state.

Fig. 4 Process monitoring system overview

We continue developing hybrid metal AM machines equipped with the necessary functions for mass production, to contribute to  societal goals by implementing new technologies and working closely with our customers to simplify design and manufacturing.

Yoko Hirono(DMG MORI CO., LTD.)