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Laser Welding Services

Laser welding is a fusion welding process used to join together metals or thermoplastics using a laser beam. The highly concentrated heat source means that thin materials can be welded together at high welding speeds and it can produce narrow, deep welds between square-edged parts in thicker materials.

There are two fundamentally different modes of laser welding – conduction limited welding and keyhole welding. Each type differs according to the power density of the laser beam, with conduction welding having a density typically less than 105W/cm2. This means that the laser is only absorbed at the surface of the material without penetration. These type of welds typically show a high width-to-depth ratio.

Higher power densities are used for keyhole based laser welding, with the laser producing a power density that is typically > 106-107 W/cm2. This higher power means that the beam doesn’t just melt the material but actually vaporises it before significant amounts of heat can be removed through conduction. This focused laser beam penetrates into the workpiece, creating a cavity (or ‘keyhole’) that becomes filled with metal vapour that can sometimes ionise to form a plasma. The vapour or plasma helps prevent the molten walls of the cavity from collapsing. Meanwhile, surface tension causes some of the molten material at the leading edge of the keyhole to flow around the cavity to the back, where it solidifies to form the weld; creating a cap with a chevron pattern pointing backwards towards where the weld initiated.

There are several types of lasers that are used in welding systems including solid state lasers that can be used to join a wide range of materials. 

 

Press Releases

Find out more about laser welding at TWI:

Core Research Programme (CRP) and Joint Industry Projects (JIP)

Core Research

Each year the TWI Core Research Programme (CRP) addresses challenges on behalf of our Industrial Members as well as developing specific technologies and processes. Each of the projects under the CRP is focussed on engineering, materials or manufacturing technologies, including diffusion bonding.

Joint Industry Projects

TWI also conducts Joint Industry Projects (JIPs) that bring together groups of Industrial Members to share the cost of research activities in areas of mutual industrial interest, gaining exclusive access to the outcomes. These projects cover a broad range of topics, including diffusion bonding.

Advantages

Deep penetration (or keyhole) laser welding is a non-contact, single sided, line-of-sight joining process capable of producing high aspect ratio welds (narrow width and large depth) in a range of metallic materials. The laser welding process can be performed at atmospheric pressure but inert gas shielding is needed for welding more reactive materials.

Laser welding has a low heat input compared to arc welding processes because of efficient absorption of the laser beam by the keyhole.

The laser welding technique offers high productivity from fast processing speeds with thinner materials as well as allowing thicker materials to be welded with a deep penetration on a single pass.

As well as these productivity advantages, the automated nature of laser welders make the process both highly reliable and highly repeatable.

Because the heat inputs are lower than with gas metal arc welding methods, laser welding can be used for materials that favour a low heat input or require minimal thermal distortion.

Among the advantages of laser welding is the production of higher quality welds as the beam melts the materials to form a join.

Other Considerations

Laser welding had proven to be challenging for welding aluminium alloys, because of the high reflectivity (low absorption) of aluminium when compared with other metals as well as the high thermal conductivity of the material, which can cause issues with the initiation and stability of laser welds in aluminium. However, the introduction of higher powered Neodymium:Yttrium Aluminium Garnet (Nd:YAG) and Ytterbium fibre lasers has made laser welding of aluminium not just possible but actually a viable option for a number of applications.

Although laser beam welding can be used with dissimilar metals, but the formation of intermetallic compounds (IMCs) at the weld interface can make this challenging.

Although welding machines create enough heat conduction to meet the melting temperature of metallic materials, laser welding can be combined with other welding processes, such as gas tungsten arc welding, to allow filler metal to be added into the heat affected zones during welding, helping to further control the weld properties and increasing welding speeds.

Laser Welding at TWI

Laser welding is a versatile fusion welding process, which has found a number of applications in industry; from welding of car bodies and aircraft fuselage panels to the welding of shipbuilding structures down to joining components in medical devices.

The process can be used to weld a variety of materials including, carbon steels, stainless steels, titanium, aluminium and nickel alloys.

The industrial uptake of laser welding has been driven by requirements such as high volume production, high quality welds and/or low weld distortion.

TWI has considerable experience in the successful development and qualification of laser welding procedures for a variety of different applications, across numerous industry sectors.

Contact us to find out more and see how we can assist with your laser welding operation and joining technologies. 

For more information please email:


contactus@twi.co.uk