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Photonics Solutions for the Metal Industry

Laser Welding

Laser Welding

Laser Welding Solutions and Advantages

Laser welding is one of many industrial laser processes and is used to join various materials together by creating a strong weld between them. This process can be used to create a strong and permanent joint between two types of material. The laser being used focus a beam of high-intensity light on a desired area. The aim of the laser welding process is to physically melt the two materials together to form a bond between them. Although such technology is mostly used to join metals, it can also process other type of materials such as plastics and silicone.

Laser welding method provides ultimately precise heat input to the desired area with narrow full penetration weld which makes an aesthetic final result with close to zero welding oxidation. When thin large sheets are joined, laser welding (in many cases) is the only welding method to avoid thermal and physical distortion of the end product without additional processing. Laser welding is the best welding method to minimize loss of base material properties, such as hardness and strength. The laser joining process can be used in both: hand held precise small jobshops and large-scale automated workshops, allowing welding speed of 1-5m/min. Laser welding is over 5 time faster than MIG and over 10 times faster to TIG. Low waste and simple maintenance makes this technology user and environmentally friendly.

Laser technology has developed progressively over the last 60 years. It is commonly used for traditional processing applications, for example, cutting, marking and welding, especially in fields such as aerospace, which exploit the use of advanced materials. Laser welding is used to join pieces of metal or thermoplastic. A high-density beam is focused on the surface of the materials, causing them to melt and interfuse. The materials crystallise after cooling down and a tight join is formed.

Laser welding has many advantages over conventional welding processes. First, laser beam irradiation causes the crystal grain to grow unidirectionally and exhibit a very fine dendrite structure, resulting in excellent mechanical properties and therefore exceptional anti-cracking and anti-porosity capabilities. Second, the small size of the laser beam affords much lower thermal stress and thermal effects, so the joining of refractory materials and dissimilar metals is increasingly feasible. Moreover, laser welding emits less harmful substances.

There are various types of laser for different applications on the market. For laser welding alone, there are many types of laser for different techniques. We focus here on the welding performance of four types of laser, namely the master oscillator power amplifier (MOPA) nanosecond (ns) pulsed fibre laser, quasi continuous wave (QCW) fibre laser and yttrium-aluminium-garnet (YAG) laser and the (CW) continious Wave laser. The ns pulsed fibre laser is based on the MOPA structure and features eight adjustable pulse widths. 

Advantages
  • Close to zero physical distortion – when thin large sheets are joined, laser welding avoids thermal and physical distortion of the end product without additional processing.
  • Low welding oxidation – Fiber laser welding method provides ultimately precise heat input to desired area with narrow full penetration weld which makes an aesthetic final result.
  • Excellent mechanical properties – laser welding does not affect material or its structural properties.
  • Easy to operate even for weld beginners – due to laser welding memory of set up parameters.
  • Very high efficiency – laser welding is >5 times faster than MIG and >10 times faster to TIG.
  • Long and wide sheets welding
  • Cost efficient welding solution – low energy consumption.
  • Allows welding of sheets with different steel grades and dimensions.
Drawbacks
  • Relatively high single-time investment costs compared to traditional methods.
  • Standard Fiber laser welding requires a tight fit between the parts to be joined, which is not the case with our wobble laser welder.  In many cases it is best to redesign the joint locations to present overlapping surfaces for normal fiber lasers, but our wobble laser can handle none tight fit connections..
  • Limited material thickness (today’s maximum 10mm single sided).

Laser welding has become an established technology in metal device manufacturing due to the following key advantages:

Process repeatability: Laser welding/cutting/marking, engraving, cleaning are non-contact processes which eliminates potential problems caused by wearing parts, contact deformation or contamination.

Process control: The high beam quality and a resulting spot size control together with the continuously tunable average power of a Fiber Laser ensure that the energy is delivered only where it is needed and with exceptional control. This enables for example that Laser welds can be placed very close to polymer seals, glass-to-metal seals, soldered components, and thermally sensitive electronic circuits.

Hermeticity: Unlike soldering or brazing, Laser welding can provide high quality hermetic welds with high yield, both of which are fundamental requirements in the manufacturing of high value implantable medical devices.

Surface finish: In addition to the aesthetic quality, the smooth and pore-free surface finish achievable enables reliable autoclave sterilisation.