Metal additive
manufacturing

Metal Additive Manufacturing at LORTEK

The wire arc additive manufacturing (WAAM) technology is a directed energy deposition process that uses an arc welding equipment to melt and continuously deposit material in wire form.

This technology allows the bead-by-bead manufacture of 3D parts, adding layer on layer, with no size limit (the limit depends on the working space of the welding equipment), and with high deposition rates (up to 4 Kg/h for steels, and 2 Kg/h for aluminium and titanium alloys).

MIG-MAG, TIG and plasma welding sources can be used as preferred welding process. Additionally, simultaneous melting and deposition of several wires can be performed, multiplying the aforementioned deposition rates by 2.

The technology allows to work with traditional filler metals, thus drastically reducing the material costs (up to 10 times less than the same alloy in powder format) and simplifying its handling. Likewise, the process can be carried out in robotized cells and traditional automatic welding systems, which minimizes investment and training costs.

The main limitations lie both in the need to apply final machining to the part as a near-net-shape part is obtained, and in the control of residual stress and distortions that are generated, above all in massive parts.

This technology is currently of interest in different sectors, but particularly aerospace, naval, automotion, moulds and dies, energy and construction (architecture). Applications with high added value materials where the buy-to-fly ratio is very high are particularly suitable. In these cases, it is possible to achieve reductions of 70 to 90% in material consumption, which justifies its use as an alternative technology to traditional manufacturing processes such as milling or lathing.

What we are currently working on

  • Research in process monitoring technologies for the early detection of defects (porosities, lack of fusion).
  • Research in non-destructive inspection technologies (ultrasound, radiography, tomography) to detect defects that are smaller in size than those demanded by the standards (defects of less than 0.5 mm).
  • Study of structural integrity (fatigue life, fracture, creep, and corrosion) of the manufactured parts.
  • CAD/CAM tools and process simulation for the automatic manufacture of 2.5D (sections in 2D extruded in z-axis) and 3D parts.
  • Development of advanced deposition strategies to reduce the necessary machining oversizes and to minimize distortions of the manufactured parts.
  • Optimization of thermal treatments after deposition to achieve a good balance of properties, and eliminate residual stress.
  • Development of new WAAM processes with greater deposition rates by incorporating multi-wire technologies (e.g., CMT TWIN) and hot wire technologies (e.g., TIGSpeed). The objective is to deposit more than 8 Kg/h of carbon and stainless steels, and 5 Kg/h of aluminium and titanium.
  • Development of new alloys for WAAM (e.g., new high resistance aluminium alloys).

Specific Equipment

Power sources for different welding technologies

  • MIG-MAG: Fronius TPSi and Fronius Transpuls (2) with different synergic curves including CMT.
  • MIG-MAG: Fronius CMT TWIN.
  • TIG: EWM TigSpeed with cold and hot wire feed options, with and without oscillation.
  • Plasma: SBI with automatic wire feed.

WAAM robotized cells

  • 6-axis KUKA KR16.
  • 1 ABB IRB 4600-45/2.5, 6 axes and 2 additional external axes.
  • 1 FANUC Arcmate 120iC, 6 axes and 2 additional external axes.

CAD/CAM software

  • SKM DCAM.
  • Delcam PowerMill Additive.

Distortion prediction and control software

  • Abaqus.

Protection system for WAAM of active metals

  • Inert chamber (250 x 150 x 150 mm).
  • Local shielding system developed and patented by LORTEK.

Process control equipment

  • SERVO-ROBOT and SCANSONIC seam tracking system.
  • Infrared thermographic camera.
  • Temperature monitoring systems: Pyrometer and thermocouples.
  • Artificial vision cameras for welding.
  • Laser profilometers for inspection of weld bead dimensions.
  • Process data acquisition system.

Part inspection equipment

  • Ultrasound.
  • Thermography.
  • Collaboration with third parties for other tests: metrology, X-rays and computerized tomography.

Publications and downloads

Publications
2021
M. Arana, E. Ukar, I. Rodríguez, A. Iturrioz, P. Álvarez
Strategies to Reduce Porosity in Al-Mg WAAM Parts and Their Impact on Mechanical Properties.
Metals, 11(3), 524.
Open link
2020
L. Vázquez, N. Rodríguez, I. Rodríguez, E. Alberdi, P. Álvarez.
Influence of interpass cooling conditions on microstructure and tensile properties of Ti-6Al-4V parts manufactured by CMT-WAAM.
Presented at 2nd International Congress on Welding, Additive Manufacturing and Associated Non-Destructive Testing (ICWAM), Metz (France), June 2019.
Open link
2020
L. Vázquez, I. Huarte, N. Rodríguez, P. Álvarez.
Influence of post-deposition heat treatments on microstructure and tensile properties of Ti-6Al-4V parts manufactured by CMT-WAAM.
Presented at 2ⁿᵈ Metallic Materials and Processes: Industrial Challenges, Deauville (France), October 2017.
Open link
2018
A. Paskual, P. Álvarez, A. Suárez.
Study on arc welding processes for high deposition rate additive manufacturing. Procedia Cirp, 68, 358-362. Published in 2018.
Open link
2018
N. Rodríguez, L. Vázquez, I. Huarte, E. Arruti, I. Tabernero, P. Álvarez
Wire and arc additive manufacturing: a comparison between CMT and TopTIG processes applied to stainless steel. Welding in the World, 62(5), 1083-1096. Published in 2018.
Open link

Success Cases

Manufacture by means of WAAM of Ti parts for aeronautical applications.

Challenge

Manufacture of Ti WAAM parts for aeronautical applications.

Solution

Development of WAAM process of Ti-6Al-4V alloy by CMT technology in open environment (with local shielding system), and reaching deposition rates of up to 2.3 Kg/h. The components developed satisfy the quality specifications of forged products after applying optimized thermal treatments.

Partners or strategic alliances

Work developed within the framework Of ADITARC project, and with the collaboration of aeronautical forged component companies.

Study of fatigue life of Ti-6Al-4V WAAM parts

Challenge

Study of fatigue life of Ti-6Al-4V WAAM parts.

Solution

Manufacture of fatigue test samples from WAAM walls and characterization (computerized tomography, low and high cycle fatigue testing).

Manufacture of high strength Al WAAM parts

Challenge

Manufacture of high strength Al WAAM parts.

Solution

Development of WAAM process of new high strength aluminium alloys (2219, Al-Mg-Sc and Al-Li), including the optimization of the welding process, deposition strategy and thermal treatments. Strategies to reduce oxidation

Partners or strategic alliances

Work developed within the framework of the EcoTECH project, with collaboration from Sonaca and Cranfield University.

WAAM in hybrid system combining additive and subtractive technologies

Challenge

WAAM in hybrid system combining additive and subtractive technologies.

Solution

Study of the manufacturing process by WAAM of aluminium parts in hybrid system from the manufacturer Diversified Machine Systems (DMS) with Fagor Automation CNC numeric controller.

Partners or strategic alliances

Fagor Automation, Aotek, Goierri Eskola.

Challenges

Challenges to be faced in the coming years:

Guarantee the quality and structural performance of parts manufactured by WAAM and achieve their certification for different applications.
Minimize manufacturing times and costs.
Distortion control.
Develop new success cases in collaboration with industry: alternatives to forged parts and repair of parts and moulds.
Industrialization of technology.