Funded under the European Brite-Euram Programme

Number BE97-4661-MICDRILL

Partners: Higar Engineering (UK), AEA Technology(UK), APNES (IT), ESIL (IE), ISQ (PT), Lasindustria (PT), Rolls-Royce (UK) and RTM (IT)

The micro-drilling of harder materials (above 500 HV), using conventional techniques, was limited to 150 micron at the start of the project. However, several applications, as for example in the aeronautics (turbine components: combustors and turbine blades), automotive (diesel nozzles injectors), microelectronics and medical fields, would significantly benefit if the actual technological constraints to drill holes smaller or, for turbines, cheaper could be overcome. On the other hand, developments in the existing technologies able to provide higher production rates and better process control, would prove to be an important step forward in the existing technologies performance.

In a highly competitive industry such as aeronautics the manufacturing of combustors involves the drilling of many thousands of holes with diameters in the range of 400-600 micron. The development of processes that would allow the drilling of smaller holes at higher production rates would represent a vital step forward. A trend for the future of the automotive industry is the development of direct injection petrol engines. For this it is crucial to develop manufacturing systems able to drill holes, perpendicular and oblique to the injector, with an average 80 micron diameter in order to increase fuel efficiency and reduce pollution levels. The electronics industry is another potential industry whose development towards higher miniaturisation requires higher machining precision to enable micro-drilling to be an effective technology.

Therefore, the ultimate goals for the project were twofold: the development of technologies which will allow the micro-drilling of holes smaller than 125 micron in diameter in metallic materials with thickness around 1 mm; secondly the development of existing and industrially established technologies to allow higher processing speeds and better processing control. Conformance with health and safety legislation is a common issue to both research directions.

The industrial objectives pursued by the present project were:

·development of the electron beam process for micro-drilling of large batches with high production rates;

·development of the copper vapour laser (CVL) and doubled frequency Nd:YAG laser (green laser) processes to industrially reliable systems by means of parameter control and definition of technical strategies;

·assessment of EDM technology as a reference process to compare developments to be achieved in other technologies.

The project was expected to lead to consistent, reproducible and controlled techniques to perform holes with diameters lower than 100 micron with good geometrical characteristics (circularity and parallelism). Specifically the objectives were that the proposed developments lead to improvements in production by a factor of 5-10 compared to existing technologies and to an increase in quality in terms of being able to decrease the size of holes by a factor of 2.