Post on 18-Mar-2020
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LASER BEAM DRILLING
F R A U N H O F E R I N S T I T U T E F O R L A S E R T E C H N O L O G Y I LT
DQS certified by
DIN EN ISO 9001
Reg.-No.: DE-69572-01
Fraunhofer-Institut
für Lasertechnik ILT
Director
Prof. Reinhart Poprawe
Steinbachstraße 15
52074 Aachen, Germany
Phone +49 241 8906-0
Fax +49 241 8906-121
info@ilt.fraunhofer.de
www.ilt.fraunhofer.de
Fraunhofer ILT – Short Profile
The Fraunhofer Institute for Laser Technology ILT is worldwide
one of the most important development and contract research
institutes of its specific field. The activities cover a wide range
of areas such as the development of new laser beam sources
and components, precise laser based metrology, testing
technology and industrial laser processes. This includes laser
cutting, caving, drilling, welding and soldering as well as
surface treatment, micro processing and rapid manufacturing.
Furthermore, the Fraunhofer ILT is engaged in laser plant
technology, process control, modeling as well as in the
entire system technology. We offer feasibility studies,
process qualification and laser integration in customer
specific manufacturing lines. The Fraunhofer ILT is part
of the Fraunhofer-Gesellschaft.
Subject to alterations in specifications and other technical information. 04/2016.
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At pulse durations of less than 10 ps, the material evaporates
completely, and there is almost no heat transfer into the
workpiece. With proper movement of the laser, drill holes can
be created without leaving melt layers on the drill hole wall.
Through the use of related systems technology, high quality
cylindrical and conical drill holes can be created that feature
high aspect ratios.
Application Areas
Due to the high intensity of the laser pulses, nearly all materials
such as metals, ceramics, semiconductors, CFRPs, plastics,
as well as multilayer systems made using these materials can
be drilled with great precision. Areas of application include
the making of air-cooling holes in turbomachinery components
such as blades or combustion chambers, drill holes for fuel
filters or injection nozzles, and ventilation holes for injection
molds in tool manufacturing.
Plant and Systems Engineering
Aside from its process technology work, Fraunhofer ILT
also develops the systems necessary for the industrial
implementation of these drilling methods. This includes
the development of specialized helical drilling optics with
high-speed local laser beam modulation, in addition to drilling
process integration within automated production systems.
Equipment
Fraunhofer ILT has a number of modern laser systems
used for laser drilling. These include:
• Long-pulse lasers (pulse durations µs - ms) such as
- IPG fiber lasers with 6 kW peak output power
- IPG single-mode fiber lasers with 1.5 kW peak
output power
• Short-pulse lasers (pulse durations ns - µs) such as
- Edgewave double-pulse laser with 2 x 40 W mean output,
pulse duration 2 - 10 ns, 50 kHz
• Ultrafast lasers (pulse durations fs - ps) such as
- Amphos 500 with 400 W mean output, pulse duration
0.7 - 8 ps, repetition rate up to 54 MHz
- Trumpf TruMicro 5270 with 60 W mean output,
pulse duration 7 ps, repetition rate 400 kHz
For optical beam formation, Fraunhofer ILT also offers drilling
optics with focal lengths of 70 to 300 mm, helical drilling optics,
and various scanning systems.
Contact
Dipl.-Ing. Hermann Uchtmann
Telephone +49 241 8906-8022
hermann.uchtmann@ilt.fraunhofer.de
Dr. Arnold Gillner
Telephone +49 241 8906-148
arnold.gillner@ilt.fraunhofer.de
The Method
Depending on component thickness as well as required
quality (precision) and productivity (drilling duration), holes
of approximately 1 µm to several millimeters in diameter are
drilled into the workpiece by means of single pulse drilling,
percussion drilling, trepanning, and helical drilling. The follow-
ing table shows the distinctions among the various drilling
methods with respect to diameter, depth and duration.
Diameter Depth Duration
Single-pulse drilling 40 - 700 µm < 2 mm < 1 ms
Percussion drilling 50 - 700 µm < 20 mm 0.1 - 20 s
1 - 50 µm < 1 mm < 1 ms
Trepanning 0.3 - 10 mm < 10 mm 1 - 20 s
Helical drilling 10 - 200 µm < 2 mm > 10 s
Single-pulse drilling can be performed “on the fly,” so that
up to 300 holes per second with a diameter of 60 µm can
be drilled into metal sheets of 1 mm in thickness. Trepanning,
which involves relative movement between the workpiece
and the laser beam, is used for drill hole diameters larger than
approximately 300 µm. Helical drilling is used to create holes
that have both highly precise geometry and superior
metallurgical quality. Laser drilling is an alternative to methods
such as electron beam drilling, electrical discharge machining,
electrochemical drilling and ultrasound drilling. The use of
“light as a tool” is preferred when the manufacturing process
requires drill holes with diameters of approximately 1 to
500 µm and high aspect ratios (> 1:20) to be made under
difficult conditions, such as those involving large inclination
angles to the workpiece surface, or materials of high hardness
(e.g. nickel-based alloys). Challenges exist with respect to the
minimization of melt layers and the avoidance of micro cracks
in the drill hole wall.
Physical Basis of the Process
Laser drilling methods can be distinguished into melting-
dominated and evaporation-dominated methods. At pulse
durations ranging from microseconds to milliseconds, the ma-
terial is largely melted by the laser, a small portion evaporates.
The resulting steam pressure expells the melt out of the drill
hole. This drilling process is highly productive; however, melt
layers with thicknesses of up to 100 µm still adhere to the
drill hole walls.
LASER BEAM DRILLINGBy laser radiation holes can be dri l led with diameters ranging from less than one micrometer to several
mil l imeters while maintaining the same dri l l ing depths. The Fraunhofer Inst itute for Laser Technology ILT is
developing several drill ing processes ranging from fundamental research to industrial systems implementation.
Application areas for laser dri l l ing include injection nozzles, venti lat ion holes, air-cool ing holes, contact
dri l l ing and f i l ter holes.
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3 Laser-drilled coupling element.
4 Fraunhofer ILT helical drilling optic.
5 Individual drill hole in CFRP
preform for functional elements.
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Cover: Laser drilling of a jet-nozzle segment.
1 Laser drilling of a nozzle guide vane element.
2 Helical drilling of nozzles
for CO2 air conditioners.