Laser Drilling |
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Without touching the workpiece, the laser beam produces
holes – from ultrasmall to relatively large – in metals, plastics,
paper, and stone |
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Some of the first applications in the 1960s
included drilling jewels used as seats for watch mechanisms
and drilling diamond dies used in drawing metal wire. Later,
techniques were developed for drilling turbine blades in aircraft
engines. Since the late 1990s, new applications have
emerged such as drilling injection nozzles for engines or perforating
foil used in packaging. |
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How laser drilling works: the laser melts and vaporizes the material. The vapor pressure expels the molten material 1 from the hole. |
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In laser drilling, a short laser pulse with high power density
feeds energy into the workpiece extremely quickly, causing
the material to melt and vaporize. The greater the pulse energy
is, the more material is melted and vaporized.
Vaporization causes the material volume in the drilled hole
to increase suddenly, creating high pressure. The vapor pressure
expels the molten material from the hole. Spatter and
vapor shoot upward in the direction of the processing optics.
Once the laser beam breaks through to the other side, the
spatter and vapor exit through the bottom. To prevent damage
to the processing optics, manufacturers design the machines
so that there is a large distance between the optics
and the workpiece. A coaxial gas flow can also be used to
shield the optics from spatter. |
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A laser drills a hole in a connecting rod. The hole allows lubricant to flow to the contact surface. |
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Different drilling processes
Over the years, several
drilling processes have developed from the basic method:
single-shot drilling and percussion drilling as well as trepanning
and helical drilling. The ideal drilling
process depends on the required hole geometry and quality
as well as the predetermined cycle time. Single-shot drilling
is used when a large number of holes need to be produced
in a short time. Multi-pulse percussion drilling is suitable for
small hole diameters or deep holes. Trepanning and helical
drilling can be used to create holes of any diameter. As the
pulse count increases, so does the drilling time. |
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Single-shot and percussion drilling