Laser welding is a discrete process and although filler material can be used to enhance joint strength and viability, the usual method for laser welding is to weld two surfaces together without “filler” or intermediary material. In the medical device industry, the absence of a third material between two surfaces being welded together has advantages in that only the “parent” materials need to be approved for medical use.
Attica produces miniature metal assemblies by laser welding (laser spot and laser seam welding) and other micro-welding techniques. Metals which can be joined include stainless steels, nickel alloys such as Kovar, Monel or Hastelloy, titanium, platinum and other precious metals. The joint area is shielded with Argon to reduce oxidation in the weld area, rather than being placed under a vacuum, as is the case with electron beam welding. Laser welding is therefore an economic solution when large quantities of similar assemblies require welding.
Rotary laser welding is a useful technique for joining the inside diameter of one precision tube such as an hypodermic tube to the outside diameter of a second tube, or for joining circular stamped parts or fine blanked parts. Special needles including biopsy needles can be made by laser welding a precision machined hub, for example, to a hypodermic tube.
Other medical devices, such as drug delivery devices, catheters, venous filters and stents, can also be usefully assembled by laser welding. Components made from stainless steel or titanium foil can be laser welded together, for example in the manufacture of heart pacemakers.
Micro-sectioning a laser weld shows a seam of overlapping molten metal hemispheres, which have re-solidified and overlapped to create a precision seam weld.
Laser welding can also be used to weld together different materials. For example, copper wire can be laser welded to stainless steel components, creating a discrete, strong, electrically conductive joint.