Laser Micromachining and Surface Modification Database

Objectives

• Characterise the surface modification and micromachining of a wide range of materials using an ultrashort pulsed laser
• Investigate the effects of picosecond laser pulses on key materials, with a view to transferring this knowledge to real parts and products in later project work
• Development of a new project leader who will become the TWI specialist in this field in addition to the skills acquired during the EngD programme
• Establish TWI as a knowledge centre for ultrashort pulsed laser processing of materials for surface modification and micro-structuring

Project Outline

The concept of this project is to develop a state-of-the-art ultrashort laser processing facility, and a design database of process parameters for key materials. This will provide a new research facility, which can be used to develop micromachining and surface modification processes, for a range of materials and applications.

Several materials deemed important for their respective industries will be selected and processing trials will be conducted, altering the wavelength, scanning speed, pulse repetition rate, average power and pulse energy. This will enable TWI members to access laser micromachining technology, accompanied by experimental data to help assess its viability for specific applications.

Current materials under consideration, together with their respective industry sectors are listed in Table 1.

Table 1 - Candidate materials for database inclusion, grouped by industry sector

Relevant Industry Sectors

• Aerospace
• Automotive
• Electronics
• Medical
• Oil and Gas
• Power

Industry Need

Ultrashort laser processing potentially offers extensive advantages over other methods, such as longer-pulsed or continuous wave laser technology, in high value manufacturing industry. Using a single laser system, the following benefits can be achieved:

• Limited thermal damage to components (negligible heat-affected zone)
• Extremely precise (~10μm repeatability) marking for decorative or functional applications
• Production of multifunctional complex parts (for example, intricate conductive tracks on a substrate)
• Contactless machining at the micro/nano level
• Surface modification, i.e. introduction of chemical changes to a surface as a preparative procedure to improve adhesion (improvements of the adhesion strength by a factor of at least 10 have been found for those polymers that have been laser treated) by modifying the friction co-efficient or altering the hydrophobicity/hydrophilicity
• Applicable across a wide range of material types
• Negligible consumables
• Higher-throughput processing

By varying the process parameters (particularly power and energy density), the effect can range from surface cleaning to chemical surface modification and finally material ablation/removal. Parameters can also be fine-tuned to increase either hydrophobicity or hydrophilicity, depending on the specific conditions applied.

Most of these advantages are not currently offered by other laser processes. Examples of laser micromachining and surface modification applications are presented in the attached schematic.