The automotive and aerospace industries are utilising a higher proportion of composite materials, such as carbon fibre reinforced plastic (CFRP), to improve efficiency and reduce carbon emissions. Machining CFRP at the required productivity rates whilst maintaining material integrity is an ongoing challenge. Most mechanical and laser based techniques tend to reduce the material integrity at the required processing speeds. In particular, machining demonstrations with high power fibre and CO2 lasers produced large heat affected zones (HAZ). Alternative approaches utilising pulsed laser systems, in either the nanosecond or picosecond regime, reduce the HAZ but are either limited in average power or are complex and expensive systems. This project will aim to develop and demonstrate a laser-based technology that is capable of overcoming the current limitations.

High absorption in both the carbon fibres and the surrounding polymer matrix should ensure the CO2 laser is an ideal choice for machining composite material. Typical commercial CO2 lasers operate in a long pulse regime of >5us at high average powers. However, the long pulses create a large HAZ which reduces the material integrity. Q-switched lasers with pulse widths <300ns are available but at typical average powers of <50W, insufficient for the required productivity.

This project will involve modelling and demonstrating novel techniques for short pulse generation and amplification in a cost effective, reliable CO2 laser architecture. A novel approach to resonator design will be employed to Q-switch a high power CO2 laser to produce >500W average power at pulse widths <250ns. Alternatively, a novel Q-switched source will be used to seed a MOPA using innovative extraction techniques to generate >500W average power at pulse widths <250ns.The final system will be used to develop optimised machining strategies for CFRP. This will be supported by modelling undertaken within the project.

The combination of high average power and short pulse width in a cost effective, reliable architecture is not currently available. By developing this laser system this project will generate a solution suited to machining a range of composite materials.

This project gives the student the opportunity to work within an established and dynamic development team that has a long history of innovation and success in creating products suited to a range of industries.