STI uses laser welding technology to assemble components composed of multiple metal parts welded together by means of a laser beam. Due to its relatively low heat input, laser welding enables a range of micro welding applications that require high-quality welds impossible or difficult to achieve with other welding technologies, such as thinner materials and micro assemblies.
Micro laser welding takes a small amount of energy and projects a focused laser beam (spot diameter ≥ 40μm) on a metal surface. STI uses 2-100 Watt pulses from a solid-state Nd:YAG source. A pulse of concentrated heat melts the metal at the configured joint without any filling materials. Micro welding is performed under microscope to ensure accurate positioning of parts and maintaining good contact between them.
Laser welding advantages
- Deep and narrow welds proportional to the power supplied
- Minimal thermal affect reduces post-processing steps
- Given small gap (0.05-0.1mm), no need for filling material
- Accurate welding in areas where access is difficult
- High weld strength, non-porous and hermetically sealed
- Welding of diverse materials and thickness
- High welding speed – economic production rates
Laser welding geometry Joint configuration – welding geometry
CNC laser welding enables automatic and accurate assembly of complex shapes by joining parts in difficult to reach areas and welding most joint configurations, including: Lap, butt and corner joints.
Smaller gap (< 0.1 mm) between welded parts improves welding quality. STI optimizes its laser welding process to suit specific applications and exact product specifications by closely controlling such welding parameters as: spot size, laser beam intensity, pulse repetition (frequency), pulse overlap, and control over the gap between parts.
Laser welding radiopaque markers Mixed-metal spot welding of radiopaque markers
|Biocompatible metal||Marker (precious metal)|
|Nickel Titanium (Nitinol)|
Cobalt Chromium L605 / MP35N
Stainless Steel 316LVM
|Spot weld diameter||0.04-0.1 mm|
X-ray visibility of small medical devices, such as stents, decreases with their size therefore requiring radiopacity enhancements.
The lower photo shows a Gold marker improving X-ray visibility of a Nitinol stent.
Radiopaque markers are made of precious metals, such as: Gold, Tantalum and Platinum-Iridium. Marker sleeves can be riveted, whereas disc shapes get welded into special eyelets with a minimal spot diameter of 40 microns (0.04 mm).
Nitinol stent at X-ray
Laser seam welding
CNC laser welding combines axial motion with laser control to create a thin seam weld by consistently applying a series of pulses along a continuous contour. The overlap percentage between pulses affects the sealing quality.
STI hermetically seals implantable devices and welds small cutting or probing tools to endoscopic tubes. Common applications include endoscopic and arthroscopic surgical tools.
STI also uses laser seam welding to assemble products from several components having different mechanical properties. Manufacturing orthopedic nails, for example, involves laser seam welding of hardened bars which provide structural strength onto an annealed tube that facilitates factory crimping and intra medullar expansion.