Description

The laser-welded finned tubes are manufactured by helically winding strip onto tubes. The fin strip vertically applied to the tube is welded at it’s foot by a welding technique without filler metal to the tube wall. This process provides a crevice-free weld between the strip and the tube.
The use of the Laser technique for the winding of finned tubes offers a number of advantages due to the ability of the beam to be very accurately focussed, allowing full use of the beam's high thermal capacity. These advantages are in particular:

• Thin, continuous weld seam, weld seam depth <0.2 mm.
• Small heat-affected zone avoids any deformation of the material. This results in a
  high stability of shape and a great accuracy of size of the welded finned tube.
• Short heating time.
• Only slight microstructural change in tube and fin.
• High utilization of heat for forming the beam.
• No contamination of the weld seam, as the Laser-welding is carried out under a protective atmosphere.