Heriot-Watt Laser System Facilitates Breakthrough In Welding Technology

The manufacturing industry has experienced a recent breakthrough in welding technology thanks to the efforts of scientists from Heriot-Watt University in Edinburgh, Scotland. The new Heriot-Watt laser system facilitates the fusing of metal and glass together. These two materials are difficult to join due to their strikingly disparate thermal properties. The technology utilizes an ultra-fast laser system that is capable of joining materials that, until recently, had to be joined through the use of messy and unreliable adhesives.

How The Heriot-Watt Laser System Works

The new Heriot-Watt laser system uses light that is aimed at connection points in materials to fuse them together. The result is a more reliable connection than adhesives can provide. Traditional adhesives can be difficult to work with and lead to slippage or movement over time or in harsh environments. Outgassing is another issue manufacturers currently face when working with adhesives, especially in electronics and medical fields. This is a process by which the organic chemicals in these substances release gasses which can lead to a reduction in product integrity over time, as well as contamination of sterile environments. Materials that the system has been proven to join include optical materials, such as:

• quartz
• borosilicate glass
• sapphire

which have been successfully welded to metals that include:

• aluminum
• titanium
• stainless steel

through the use of picosecond (10⁻¹² or ¹/_{1,000,000,000,000} of a second) pulses of infrared laser light.

Ultrashort laser pulses can be used to produce a spiral weld (left) at the interface between glass and metal, enabling them to be fused together (bottom middle). Image: Heriot-Watt University

The Heriot-Watt Laser System Effects On Manufacturing

The newly proven process has significant implications for manufacturing industries that routinely require the union of these raw materials, including:

• aerospace
• defense
• energy
• electronics
• optical technology
• healthcare

The manufacturing and design flexibility the Heriot-Watt Laser System provides welds that have been tested to maintain their integrity between -50C to 90C.

The spiral weld can be seen clearly here at the interface between the glass and metal. Image: Heriot-Watt University

Professor Duncan Hand, director of the five-university EPSRC Centre for Innovative Manufacturing in Laser-based Production Processes based at Heriot-Watt, said of the technology "Traditionally it has been very difficult to weld together dissimilar materials like glass and metal due to their different thermal properties—the high temperatures and highly different thermal expansions involved cause the glass to shatter." When asked how the technology differs from methods currently used by manufacturers to join the two materials, he would go on to state,"The parts to be welded are placed in close contact, and the laser is focused through the optical material to provide a very small and highly intense spot at the interface between the two materials—we achieved megawatt peak power over an area just a few microns across. This creates a microplasma, like a tiny ball of lightning, inside the material, surrounded by a highly-confined melt region."

Commercialization Of The Heriot-Watt Laser System

While the technology is not yet commercially available, Heriot-Watt scientists are working closely with a consortium, including laser firms Oxford Lasers and Coherent Scotland, as well as end-users Leonardo and Gooch & Housego. the partnership seeks to develop a prototype for the system that will bring it closer to commercialization. Glass Technology Services and the Centre for Process Innovation have geared their efforts towards another commercialization route with the packaging of OLED devices.