Dipl.-Ing. Kristian Arntz

Micro milling and laser ablation
Two technologies complementing each other

Dipl.-Ing. Kristian Arntz
Fraunhofer IPT, Germany

Aachen
22nd November 2011

© WZL/Fraunhofer IPT

Outline of the presentation
 Overview of tool making activities at Fraunhofer IPT

 Development of a platform for micro milling and laser
ablation with the enabling technologies
 Micro milling
 Laser ablation
 CAx-process chain
 Demonstrator applications for Combined micro
machining processes

© WZL/Fraunhofer IPT Seite 1

Process Technology at Fraunhofer IPT
Fine Machining and Optics
 Ultra-precision diamond machining, Precision grinding
and polishing, Precision glass molding,
FE process simulation, PVD coatings for tools and
molds
High Performance Cutting
 Multi axial milling, Precision hard milling, Precision
hard turning, Modelling and simulation of cutting
processes
Laser Machining
 Laser beam joining and structuring, Laser-assisted
machining, Laser surface treatment, Generative
assembly manufacturing, Biotechnology
CAx Technologies
 CAx Framework, Development of CAM modules,
NC simulation, NC data optization

Laser Materials Processing
Some of our Highlights
Design structures Laser surface treatment Laser beam brazing

Laser assisted turning Laser deposition welding Laser assisted metal spinning

Welding of heat exchangers Laser deburring Structures for tribology


The Tool Manufacturing Academy offers research, consulting and
qualification with leading tool manufacturing companies

Werkzeugbau Akademie

Research and Development Industrial Consulting Qualification

 Processing key aspects based on a  Bilateral projects concerning technical  Modular qualification proposals for
development- and research- roadmap and organizational issues non-graduates and graduates
 Acquisition of public research funds  Concept development and project  Top-class orators from industry and
realization science
 Accomplishment of contract research

Sample tool manufacturing with a whole process chain and the support of the institutes

Continuous collaboration on future issues in the tool manufacturing industry
Source: Summerer, Siebenwurst, Rathgeber
© Werkzeugbau Akademie Page 4

The increasing level of technology and engineering affords the
industrialization in the tool manufacture
Increased Level of Increased Level of
Technology Performance
Industrialization Academization

Focusing & Cooperation
Overall Long-term
Manufacturing Enlarged product
equipment qualification
efficiency technology quality rating
Product standardization

Process standardization
Professional
Investments Systematical use of
Technology chains research
knowledge
Synchronization

Source: Audi AG; Deckel Maho Gildemeister; t-mobile;
© Werkzeugbau Akademie Page 5

Process chain- oriented competency areas in process technology
Development/ Service/ Marketing/
Construction
Acquistion Manufacturing Assembling
Distribution

2,5D – 3D – Geometry (Surfaces-)
Surface Finishing
Pre-Processing Generation Functionalization

High Performance Cutting (HPS)

Clamping Systems

Design Structures and Functions

High Speed Cutting (HSC)

Wear protection

Hard milling/ Micromilling

CAx - Technologies

Material engineering / Metallography


Laser beam structuring – an innovative process for surface structuring
How it started: The challenge of "surface decoration"
Etching
 High manual effort
 Poor reproducibility
 Limited material range
© Eschmann Textures
 Restricted flexibility related to the structure design

Electroforming
 High manual effort
 Moderate reproducibility
 Poor flexibility
 No consistency of a (digital) data chain
© Galvanoform  Limited material range

A wider scope related to the structure design, the increase of the
reproducibility and the reduction of the manual effort require innovative
solutions for the surface texturing in the tool and die manufacturing!


"Removal rate and surface quality" – process basics
 Use of pulsed laser sources
– Pico- and nanosecond laser
 Ablation with ps-laser (1 picosecond = 10-12 sec)
– Material removal by sublimation (multi-photon-
absorption):
"Cold" ablation process => no thermal conduction
Fraunhofer IPT – Nearly all materials are processable
– Removal of a small material volume by a single laser pulse
– No melt formation on the surface
 Ablation with ns-laser (1 nanosecond = 10-9 sec)
– Linear absorption
– Predominantly melt ablation:
Thermal process with melt formation
– Limited range of processable materials
– Removal of a large material volume by single laser pulse
– Low-cost laser sources


Application example "injection mold" – free formed surface
Work piece specification
 Injection mold

 Basis material 1.2343 (X38CrMoV5-1)

 Quenched and tempered to 50 +2 HRC

 Laser structured area:
Fraunhofer IPT 196 mm x 152 mm

Result
 Large-scale and seamless surface
Fraunhofer IPT structuring
– Leather-grain K3A of the Volkswagen
Golf VI
Fraunhofer IPT – Hybrid-structure with micro- and macro
structures
– Geometrically defined pyramid
Fraunhofer IPT structures


The Integ-μ project
Developing integrated solutions for micro manufacturing

 Platform 1b, led by Fraunhofer IPT,
Germany
Research partners
 IPT, WZL/RWTH, KU LEUVEN
Industrial partners
 KERN, KISTLER, SWATCH, TWT, MT,
LASAG
Objectives
 Development of an integrated machine
tool system for a combined process of
micro milling and laser ablation
 System programmable through an
adapted CAx-platform
Integ-μ Project structure
 Special monitoring systems to provide
high reliability in micro milling

Integ-μ Platform 1b
Micro milling & laser ablation
Targeted performance
 multiple machining operations in one workholding
configuration
 processes will be used to complement each other (feature
size, material, time)
 stable micro milling process with tool steels > 55 HRC
 laser structuring of freeform surfaces with very small feature
sizes (12 μm focus diameter)
 broad range of applicable materials
Applications and market sectors
Integ-μ Project structure  Flexible and cost-effective fabrication of micro moulds and
micro parts
Novelty and impact on EU industry
 Fabrication of high precision complex 3D shapes with
 increased flexibility, better accuracy, increased productivity,
faster throughput, advanced materials and reduced handling
and plant area


Machine tool system for micro milling
KERN PyramidNano
 Travel X/Y/Z 500/500/400 mm³
 Clamping area max. 600 x 600 mm²
 Drives and guideways hydrostatic
 Workpiece weight max. 250 kg
 Feed rate 0.01 - 30,000 mm/min
 Acceleration 10 m/s² (1g)
 Rotational 360° continuous
 Swivelling -20° up to +110°
 Precision < 1μm
 Weight approx. 8,000 kg
Source: KERN
Force measurement system for micro milling
 Developed by WZL/RWTH and KISTLER


Machine tool system for micro laser ablation
KERN EVO
 Travel X/Y/Z 300/280/250 mm³
 Clamping area max. 350 x 230 mm²
 Workpiece weight max. (3-axis) 50 kg
 Rotational 360° continuous
 Swivelling -10° up to +100°
 Precision < 3μm
 Weight approx. 3,000 kg
Laser system Lumera SuperRapid
 Wavelength 1064 nm / 532 nm
 Repetition rate 80 to 1,000 kHz
(200 kHz optimized)
 Pulse width 10 ps
 Average output power 17 W / 10W
 Spatial Mode TEM00 (M² <1.3)
Source: Fraunhofer IPT Scanner system Scanlab RTC5
 Scanlab IntelliScan10 & VarioScan20i


Machine tool system for micro laser ablation – Integration concept
 Mounting plate with scanner, beam
expander and mirrors in place of spindle
 Laser source in place of tool changer
 Laser provides two wavelengths at two
separate outputs, so two beams had to
be aligned on one path
 Laser control unit
 Separate industrial PC
 Connected to machine control
 Laser safety
 Laser-safety windows
 External clearance
 Interlock
(connected to machine doors)
 Emergency shut-off
Source: Fraunhofer IPT (Machine & laser source)

Laser ablation – process development with first demonstrators
Laser ablation
 Several demonstration parts have Tool steel
been realized
 Generation of data sheets and
Copper
storage of process data into "laser
tools“ 10 mm

Steel Cooper Graphite Source: Fraunhofer IPT
(1.2343) R 8500
5 mm
Average laser 6 7 7 Source: Fraunhofer IPT
power [W] Graphite
Pulse repetition 80 80 80
rate [kHz]

Feed speed 300 300 500
[mm/s]
Wavelength of 532 532 532
radiation [nm] 7 mm
Source: Fraunhofer IPT


The software connection: Development of the CAx platform
Complete digital process chain
 Specialized CAM module for laser
ablation
 Basic and advances strategies for
toolpath planning for the laser
ablation process
 Seamless integration in NX5 (by
using the “CAx framework”)
 Stand-alone version possible
 Technology and process database
 Virtual lasertools
 Simulation tools available
Integrated CAM module for laser ablation
 Postprocessor
 Laser control software
“FlexOStruk”

The software connection: Development of the CAx platform
Machine simulation
 Simulation of Machine toolpath

 Collision detection

 Machine kinematics (linkage,
offset) is stored in technology and
process database
 Machine simulation tool can be
embedded into host system (NX)
with use of CAx framework

Machine simulation (KERN Evo with laser integration)


Combined process – test pattern and expected benefit
process issue benefit
a) micro milling
b) laser ablation
sharpness of corners high material removal
rate
a
b a

weld penetrations (bottom) sharp corners
b

weld penetrations (lateral) sharp corners with high
material removal rate
a + b (+a)
(and higher surface
quality by finishig step)

(high material removal
(a+) b + a - rate with) sharp corners
and higher surface
quality


Combined process – sharp corners


Demonstrator part by Swatchgroup: Watch plate

Source: Swatchgroup


Demonstrator part: Decorative structures with Aachen Cathedral



Source: Wikipedia

 Decorative pattern

 La Perlage / Pearl
Pattern



 Pocket (l,w,h): 7 x 1.8 x 2.3 mm³

 Slice (l,w,h): 6 x 0.6 x 0.08 mm³


 Control of form,
chamfer and burr

 Control of small radius

 Control of burr


Micro milling and laser ablation – complementary technologies
Outlook and vision
Combining powerful micro fabrication technologies can
contribute to
 reduced processing time by developing intelligent machining
and processing strategies
 New functionalities by realising adapted and highly
sophisticated surface properties
 increased quality by realising special features and locally
adapted properties

The integration of laser systems in machine tools contributes to
 the design of continous process chains including preliminary
work and finishing
 Specific setting of local material properties by automatically
combining different manufacturing processes
 Integrated CAx solutions which are able to represent and
control whole process chains


Your contact to Fraunhofer IPT
Dipl.-Ing. Kristian Arntz
Head of department Laser Materials Processing
Fraunhofer Institute for Production Technology IPT
Steinbachstraße 17, 52074 Aachen
Phone: +49 241 89 04-121
Mobile:+49 174 1902817
Fax: +49 241 89 04-6121
Mail: kristian.arntz@ipt.fraunhofer.de


Dipl.-Ing. Kristian Arntz

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