High energy density metal joining

At its Montréal facility, NRC investigates and develops procedures to join metallic products using high energy density technologies. Studies are currently underway to develop laser and electron beam welding of aerospace components.

NRC is developing expertise in laser welding and cutting of aerospace materials, using a 4 kW robotic Nd-YAG laser welding system and a 2.7 kW CO₂ laser processing centre. The technology, which can be used for welding, cladding and precise cutting of flat sheets or 3-D parts, offers many advantages. It creates a narrow heat-affected zone having little distortion, and smooth cut edges that don't require post-processing treatment due to the high energy density of the laser beam. It is faster and more precise than conventional methods, flexible, highly automated, and easily integrated into other processes. Projects are currently underway to investigate its applicability for welding and repair of fuselage and engine components.

NRC conducts electron beam processing studies using a 42.5 kW electron beam welder whose large chamber can accommodate large components or multiple parts. Assemblies are processed using a beam of electrons to generate heat at the joint and cut a keyhole into which molten metal then flows. The high energy density of the electron beam and the vacuum environment result in narrow heat-affected zones, deep welds with little distortion, and high-quality welds with very little porosity or contaminants. It can be used to join reactive and refractory metals, high thermal conductivity metals, dissimilar materials, and large sections or complex joint designs, with or without filler metal. Studies are currently underway to develop procedures for welding a different materials (e.g. Cu alloys, Zr alloys, Ti alloys, Ni-based superalloys, steels, stainless steels) as well as additive layer manufacturing of nickel-based superalloys and titanium alloys.

Equipment specifications:

5 kW robotic fiber laser (100-600 µm working fiber):

• Beam product parameter less than 4.5 mm∙mrad;
• Abicor-Binzel 4400 industrial robot;
• AB wire feeder and Fronius cold metal transfer technology (VR7000 CMT);
• Fronius TransPuls Synergic 4000 arc welder;
• Powder feed cladding and laser cutting heads;
• Electronic-controlled magnetic table for fixturing.

Diode laser processing centre:

• TRUMPF TruDiode laser 3.0 kW power;
• 40% wall plug electrical efficiency compared to 6% for comparable Nd:YAG laser;
• Beam product parameter 30 mm∙mrad (similar to Nd:YAG beam quality);
• Wavelength between 900 to 1000 nm;
• Insensitive to back reflection;
• Fully programmable 6-axis computer numerically-controlled machine (CNC) with Siemens Sinumerik 840D controller and teach panel;
• Programmable to 0.001 mm, accurate to ± 0.1 mm;
• Linear travel speeds: X & Y axes: 50 m/min; Z axis: 30 m/min;
• Rotary travel speeds: A, B, C axes: 360°/sec.;
• Equipped with a rotary table of 0.5 m in diameter;
• Large 3-D working area: X: 1.25 m, Y: 1.5 m, Z: 0.5 m;
• Head positioning via C (360°) & B (±120°) axes;
• For direct laser deposition applications, including reactive metals:
  • i) Trumpf optic head and wire feeder system;
  • ii) Precitec YC50 cladding head;
  • iii) Sulzer Metco twin-10 powder feeder.

Electron beam processing centre:

• thermionic electron emission from a tungsten filament;
• output voltage: 0-60 kV; output current: 0-700 mA;
• power range: 0-42 kW;
• high vacuum (1-100 µTorr) 68" x 68" x 84" chamber;
• wire feed: 0.02" to 0.046" wire; 0-100"/min;
• 19" gun-piece clearance on perpendicular welds;
• CNC controlled 30"Φ welding table;
• five mechanical axis of motion:
  • X – table; 33" displacement, 0-100"/min;
  • Y – gun; 50" displacement, 0-100"/min;
  • Z – table; 30" displacement, 0-100"/min;
  • R – table; 0-10 rpm;
  • T1 – table; -10 to 90°, 0-6°/sec (1 rpm);
  • T2 – gun; -10 to 90°, 0-30°/sec (5 rpm).