Mitsubishi Heavy Industries Machine Tool (MAT) has recently been awarded by JSME (The Japan Society of Mechanical Engineers) for achievements in additive manufacturing. The JSME Medal for New Technology was awarded to MAT on March 5th, 2021.
Powder DED (Directed Energy Deposition) metal 3D printing is a system to efficiently supply metal powder from a nozzle to part for laser fusing. With a printing speed about 10 times faster than PBF (Powder Bed Fusion), scaling up the equipment’s size is easy and is suitable for printing large parts. On the other hand, the prevention of material degradation by metal oxidation during melting and solidification processes and the optimum control of printing conditions (laser output, feed rate, etc.) according to the degree of heating and cooling which changes every moment are issues.
In order to solve these issues, the LAMDA machine, using powder DED metal 3D printing, is equipped with a local shield nozzle which blocks the atmospheric inflow to the melt part by the optimum injection of inert gas. In addition, the world’s first monitoring feedback function was developed for the LAMDA machines and controls the printing condition in real time by observing the melt pool.
One of LAMDA’s several unique features is the local shield nozzle, which shields the printing part area, was developed in order to enable large printing and to improve the productivity.
In this local shield nozzle, inert gas is jetted from the outer periphery of the nozzle to form a shield against the melt pool, so that the inflow of the outside air is prevented. This eliminates the need for an expensive and bulky vacuum/low pressure or other atmospheric chamber structure.
Another unique feature of LAMDA is the Monitoring Feedback function. By installing a near infrared camera on the laser beam axis, the molten metal part is observed from right above regardless of the printing direction. By controlling the printing conditions at high speed according to the measured state change, the printing accuracy is dramatically improved.
The productivity and quality of large parts printing by powder DED were greatly improved by this technology.
Currently, Mitsubishi is printing large parts with the latest LAMDA2000 prototype machine. This double-column hybrid machine combines Mitsubishi’s long experience with state-of-art large machines with Mitsubishi’s latest innovations in AM technology.
Other important areas of ongoing testing include applications in automobile transmission related parts, such as gears and pulleys, and technologies such as multi-material coatings. A promising area of development for gear manufacturing is the use of AM DED for tooling and repair of large gearbox components.