LASER MICRO MACHINING
We have long-standing experience with the production of micro laser drilling. We work hard materials which are hardly to be worked on like hardened steel, hard metal, ceramics and diamond. But we are also able to drill standard materials like high-grade steel, copper alloys and plastics very exactly.
There is a great amount of hole forms: from circularly towards elliptically and polygon up to free forms. The depth of the bore can be cylindrical or dilate conical or narrow.
On the one hand the laser can generate very small and exact holes with aspect relations up to 15. On the other hand thin tins, foils and layers are bored (almost freely of burrs) with very high speed to produce thousands of holes per minute, e.g. for perforations.
According to the application and customer preferences we suggest processes, select them and optimise them.
There are four main requirements which high precision drilling with lasers must meet: Time, quality, flexibility, and reproducibility.
The drilling time must be short enough so that laser drilling can compete with conventional drilling methods, EDM and punching.
The quality requirements are very high for micro drilling in particular. Key attributes are:
- No burrs
- Diameter up to 30µm
- Sphericity +/- 1%
- Sharp or rounded edges
- No melting or deposits
- Negligible heat-affected zone
Adjustable taper (positive, negative, cylindrical), various hole geometries within a component, material thickness of up to 1.5mm.
Reproducibility plays a major role for applications in industrial fabrication. The benchmark here is that the diameter of a 100µm hole must be reproduced within +/- 1µm for 24/7 production.
Trepanning and helical drilling
MICRO DRILLING SUCCESS FACTORS
Four influencing factors play a role in order to attain these requirements: Process know-how, laser source, drilling optics, and system technology.
A thorough understanding of the drilling procedure including all processes is required for precise and reproducible laser drilling. This is essential in order to define a suitable drilling strategy, modify process parameters accordingly during the drilling process, and to use process gases effectively.
GFH GmbH has been involved in the production of laser-drilled micro-holes since it was founded. A great wealth of knowledge about the drilling process has been accumulated in our company over the years. This knowledge allows us to provide you with competent and productive support for all your queries and applications.
The choice of laser primarily has a considerable effect on the processing time and hole quality. The geometry of the hole and the work piece material determine the optimal choice of laser with regard to pulse duration, pulse energy, wavelength, and frequency.
Various short and ultrafast lasers are available at GFH GmbH, allowing us to cover a very broad range of applications.
In order to create high precision and round micro-holes with variable aspect ratios, the focused laser beam must be made to gyrate in a circular motion. This process is called trepanning. Special drilling optics are used in order to manipulate the beam in this manner.
In order to be able to achieve high quality holes within acceptable drilling times, the drilling optics must support changes in the hole diameter during machining (spiralling). Adjusting the angle of attack should also be automated and possible during the process, since this is the only way to ensure reproducibility.
These optics rotate at several thousand revolutions per minute in order to take advantage of the high repeat rates of modern short-pulse lasers. Therefore they should not contain any adjustable components. These would change the centre of gravity, which could affect the drilling results. Also, a co-rotating intensity profile of the beam is advantageous since it allows for the production of round precision holes even if the focus spot itself is not perfectly round.
With the GL.trepan drilling optics, GFH offers its customers a product in which all of these key requirements have been implemented and which therefore provides the customer with optimal drilling results.
In addition to the drilling optics, the system technology also plays a key role. In order to be able to achieve high quality and reproducible results, the laser and optics must be fully integrated into the system. The system must also be equipped with a high precision positioning system in order to meet the very tight position tolerances typically required during micro drilling.
The GL.trepan drilling optics are fully integrated into the machine concept, therefore allowing for flexible production of high precision micro-holes.