Process and Machine Technology for …...Outline • Micromachining Examples • Functional Surface Texturing • 3D Texturing Technology • Machine Technology and Control Software
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Process and Machine Technology for Micromachining
and Surface Texturing of Complex Products
Max Groenendijk
Company Introduction • Spin-off company from University of Twente and
M2i Institute, founded in 2008, active in
• Ultrashort Pulsed Laser Materials Processing
• Offering:
– Machines for Production and R&D
– Process and Application Development
– Job Shop Production
• Specialist in Surface Texturing on 3D curved Surfaces
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Outline
• Micromachining Examples
• Functional Surface Texturing
• 3D Texturing Technology
• Machine Technology and Control Software
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There are many applications for < 100 W lasers combined with galvo-scanner beam deflection Still a lot of development is needed towards exploiting the full potential of such applications High-precision, complex processes need better control (software)
Microdrilling
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• Hole diameters down to 1 !m • Control on shape: funnel, conical,
(nearly) cylindrical
Micromilling
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• Direct write, software controlled geometries
• Machining of all materials:
• Hard: SiC, hardmetal etc.
• Delicate: polymers, membranes, very thin...
• 2,5D profiling / 3D products
hard
met
al
Processing Efficiency
• Micromilling of hardened steel • Best efficiency around 1 J/cm2 peak fluence • Only high reprates (here 6 – 8 MHz) can use full laser power • High scanning speeds are needed
– > good control on sky-writing is essential 6
Micromachining Alumina
• Round pockets ø 12,5 mm
• Depth 20 !m +/- 0.5 !m (+/- 2.5%)
• Very sensitive material
• 1% variation of laser power results in ~ 10% variation in pocket depth
• Inherent depth variations across a machined pocket are too large
• Depth variations reproduce 7
On-the-fly correction • Measure the depth variations • Generate background map • Adjust laser power on-the-fly during machining • Significant reduction of inherent depth variations
What you need: • Fast modulation of laser power • Ability to implement this strategy in your control software
8 2 !m peak to valley 0,7 !m peak to valley error map
Functional Surfaces Textures
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Manipulation of light
From engine parts to skin comfort
Manipulation of cell adhesion
Wetting Properties
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m !
Partial wetting
High speed recording
Milk-ophobic Super hydrophobic and hydrophillic surface
Tribological Properties
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Three functions of dimples: 1. Pressure build up 2. Oil reservoir 3. Wear Particle Trap
LIPSS Regimes
1. Nanospheres
2. High spatial frequency LIPSS (parallel to laser polarization)
3. LIPSS (perpendicular to laser polarization)
13 Source: M2i TULP project, Jozef Obona
Laser induced periodic surface structures
Cone like protrusions (CLP)
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Stochastic textures in steel: typical sizes and spatial frequency can be controlled by laser process
Molded Textures
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(INJECTION) MOLDING
Micro- nano textured steel mold surface
Replication of micro- nano texture in injection
molded polymer
3D Texturing Machine
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3D Laser Micromachining and Texturing Machine Picosecond pulsed laser, 5 axes + galvo Scanner
Result
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Functional surface texture
Marked outlines of the tiles
Tiles visible due to the regular dimple packing
Texturing Mirror Cup Mould
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• Demonstrator: Injection mold for car mirror cap
• Goal: obtain a super-hydrophobic effect
FP7 project Nanoclean
FP7 Project APPOLO
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• Development of technology for soft-touch surfaces in car interiors
• Our pillar textured surfaces exhibit a ‘silky smooth touch’
• Reduced friction due to largely reduced skin contact area
• Optimization of machine and further development towards industrial use of technology
Machine Technology • Goal: realize the full potential of ultrashort pulse
laser micromachining
• Processes can get complex • Processing strategies need to be well defined • High degree of control on processing parameters
• Users should concentrate on process, not on machine specific details (like scanner delays, manual calibrations and power measurements)
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• Demands for high level of integration / automation • Demands for advanced control software
Control Software • Specifically designed for step-and-scan laser micromachining • High level and machine independent programming • Structured job definitions, written in general-purpose object-oriented
programming language (Python) • Graphical preview and inspection tool (verify geometry AND
parameters) • Flexible:
– Very large and complex jobs are possible – But it is also easy and fast to compose a simple experiment
29 25.000 tiles, 30 million dimples
Details Handled Automatically • No worries about machine specific details, but focus on the
process
• Automatic and exact timing for accurate sky-writing (correct delays set automatically)
• Calibration system for scanner auto-alignment • Automatic power calibrations: program the machine in watts
(instead of percent)
• High resolving off-axis camera for accurate workpiece alignment and calibration
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Modular Micromachining System
• Flexible and highly accurate workstation for micromachining and surface texturing
• Ideal for R&D, flexible high-tech job-shops, process development
• Can be customized into single purpose production machine
• Standard system launched in summer 2014
• Reproducible results by: – Use of proven high quality components – Handle machine specific details
– Automated calibrations and power measurements
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