Laser welding of 3D prints

Titanium prints, unique technique:

No one will deny that 3D metal printing is a very innovative production technique. However, every manufacturing technology has advantages as well as limitations. One of the limitations of 3D metal printing is the limited construction area. Average dimensions of a 3D printer bed (building surface) are approximately 250mm x 250mm x 400mm.

Combination 3D printing and laser welding

By laser welding 3D metal printed parts, it is possible to develop larger components. For the combination of printing and welding, titanium alloys are preferred. Especially because titanium is excellent weldable. In addition, titanium also has a low specific weight and the material is resistant to corrosion.

When can a combination of 3D metal printing and laser welding be interesting?

• If a part is larger than the construction table of the 3D printer (3D print bed)
• When 3D metal-printed parts need to be combined with other metal parts (e.g. conventionally produced parts)
• When it is not possible to print the component at once
  • A part with different connections or functionalities cannot always be printed in one go. Factors such as building direction, accessibility for finishing … must be taken into account.

Research project ESA

Due to the innovative nature of this hybrid production method, Raytech was invited to further develop the process as part of a research project. During the project Raytech worked together with other production and research partners (Sirris, ESA, Verhaert …). Thanks to the complementary knowledge of the partners excellent welding results were obtained.

Points of attention

To laser weld titanium metal prints, adjusted welding parameters must be used. The correct setting of power, pulse length, frequency and welding speed is the first step to obtain a pressure-resistant, gastight and solid weld. The amount of energy is determined by the interaction of power and the pulse length, while the welding overlap is determined by the frequency and welding speed.

Remarks;

• Finishing surface before welding
  • Since laser welding is done without filler material, it is important to have excellent contact between the two parts to be welded. There should be no air gap between the pieces. 3D metal-printed parts can show irregularities on the edges. This means that the welding zone must be finished by means of blasting, drumming or CNC machining in order to have a smooth surface to weld (without air gap created by surface roughness).

• Porosity
  • Melting metal powder, which are actually microscopically small, irregular spheres, creates a completely massive material structure. The density of a printed metal part is 99.9% comparable to a conventional part, yet roughness and porosity can occur at the edges of a 3D printed part. This can be explained by the irregularity of the print powder weld pool. This is inherent to the 3D metal printing process according to the DMLS method. Post-processing is therefore required to finish the edges before welding.
• But or lap joints?
• Continuous or pulsating?
• Shielding gas?

More information about laser welding 3D titanium prints can be obtained by contacting Mr. Mestdagh Hendrik.