Lasers can be used to drill holes in a variety of materials, ranging from wood and plastics to metals and ceramics. Typical examples of laser drilled holes in practical applications are cooling holes in aero-engine components, holes in fuel injection nozzles and ink-jet printer heads and micro-via's in PCBs.
Some of the main advantages in the use of lasers for drilling are:
- Non-contact technique. The drilling medium is a beam of light, therefore there is no physical contact between (moving) parts and the workpiece. This prevents contamination of the workpiece and (gradual) wear of the drilling part.
- High aspect ratios possible. With lasers, holes with aspect ratios (depth to width) of for example 30:1 are easily produced.
- Holes at shallow angles. Laser drilling is particularly suited for drilling holes at an angle with the surface of the workpiece, for example, cooling holes in aero-engines. With laser drilling, holes at an angle as small as 10° with the surface can be made.
- Drilling of difficult to process materials. Lasers can be used to drill a wide spectrum of materials, from rubber and wood to very hard metals such as diamond and ceramics.
- High speed and accuracy. Laser drilling is fast, accurate and readily automated.
- Photolytic drilling with photolytic processes (i.e. those involving the breaking of chemical bonds for material removal, rather than melting and evaporation), virtually no recast layer and HAZ are formed, due to the fact that there is hardly any heat generation.
Disadvantages of the use of lasers for drilling may be:
- High capital investment. The capital investment needed to purchase a laser can be considerable.
- Thermal effects. Due to heating, a HAZ may be present around the hole, particularly with pyrolitic processes (i.e. those involving heat generation for material removal via melting and evaporation). Furthermore, thermal shock may lead to micro-cracks in some materials.
- With pyrolitic processes, due to the melting and evaporation of material, a recast layer and dross build up at the entrance and exit of the hole may be present. These reduce the repeatability and quality (for example flow characteristics) of the holes.
- Particularly in holes with a large aspect (depth to width) ratio a considerable taper may be present, which may be unacceptable.