A small volume, local shielding gas chamber with low gas consumption for Laser Wire Additive Manufacturing of bigger titanium parts

This paper shows how additive manufacturing of large size titanium parts can be achieved by means of a mobile shielding gas chamber, without the consumption of excessive amounts of shielding gas. While welding, the oversized cover of the chamber can be slid to the sides without opening it. The laser head is only partly inserted into the chamber through the cover. This enables a small sized chamber and allows a quick filling with argon. Since the chamber has a low leakage, only small amounts of argon (5 l/min) are needed to maintain a sufficient welding atmosphere with less than 300 ppm oxygen. For large sized parts, the chamber can be repositioned on the substrate. It has flexible parts which can be fit to the already welded structures that otherwise would prevent the chamber from being put flat on the substrate. The limited build space inside the chamber requires a new welding strategy, which is suggested.Mechanical Engineerin

Cladding and Additive Layer Manufacturing with a Laser Supported Arc Process

This paper describes the potential of a new process, combining the geometrical precision of a laser technique and the deposition rates of GMA cladding. Dilutions as low as 3 % can be achieved, leading to a high purity, in the first layer. Different material combinations like mild steel with X45CrSi9-3 are presented. Microsections for penetration depth determination show the high quality of the deposition layers. A hardness of the coatings of 63 HRC is reached. Hardfacing of shafts serve as an application example. The low heat input enables the process to build up structures. This results in a process variant for additive layer manufacturing which is also presented. The production of macro-sized structures is shown and discussed.Mechanical Engineerin

Influence of laser power on the shape of single tracks in scanner based laser wire cladding

The shape of the cladding tracks is extremely important for producing layers or structures by adding them sequently. This paper shows the influence of the laser power of a diode laser in the range of 500 to 1000 W on the shapes of single tracks in scanner based laser wire cladding. The scanner was used to oscillate the beam perpendiculary to the welding direction. Stainless steel (ER 318 Si) wire with a 0.6 mm diameter was used as deposition material. Height, width, penetration, molten area and weld seam angles of single tracks were obtained from cross-sections at three different positions of each track. The influence of these different positions on the results depends on the traverse speed. The paper discusses this influence in respect to the heat dissipation in the substrate material

A novel approach for high deposition rate cladding with minimal dilution with an arc - Laser process combination

First results of the process development of a novel approach for a high deposition rate cladding process with minimal dilution are presented. The approach will combine the enormous melting potential of an electrical arc that burns between two consumable wire electrodes with the precision of a laser process. Separate test for the plasma melting and for the laser based surface heating have been performed. A steadily burning arc between the electrodes could be established and a deposition rate of 10 kg/h could be achieved. The laser was able to apply the desired heat profile, needed for the combination of the processes. Process problems were analyzed and solutions proposed

Influence of the laser and its scan width in the LDNA surfacing process

The novel laser-assisted double-wire non-transferred arc (LDNA) surfacing process that melts two consumable wires with an arc between them and uses a laser to guide the process has shown very promising results. Investigations show that it is possible to create single seams with a complete bond and low dilution at a deposition rate of 7.5 kg/h. In case of multiple seams, joint defects might be formed between the seams due to unfavourable seam geometry. In this paper, results on the optimization of this geometry with an adapted laser scan width are presented. An average connection angle of 93 degrees has been achieved on the side of the weld, where additional seams are placed. It is expected that with these results multiple seams can be welded without producing joint defects, thus leading to an intact layer