1

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

2

Outline

•  Micromachining Examples

•  Functional Surface Texturing

•  3D Texturing Technology

•  Machine Technology and Control Software

3

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

4

•  Hole diameters down to 1 !m •  Control on shape: funnel, conical,

(nearly) cylindrical

Micromilling

5

•  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

9

Manipulation of light

From engine parts to skin comfort

Manipulation of cell adhesion

Wetting Properties

10

m !

Partial wetting

High speed recording

Milk-ophobic Super hydrophobic and hydrophillic surface

Tribological Properties

11

Three functions of dimples: 1.  Pressure build up 2.  Oil reservoir 3.  Wear Particle Trap

12

What textures can we make with USP lasers?

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

Nanostructures by LIPSS

14

Cone like protrusions (CLP)

15

Stochastic textures in steel: typical sizes and spatial frequency can be controlled by laser process

Microstructures

16

Molded Textures

17

(INJECTION) MOLDING

Micro- nano textured steel mold surface

Replication of micro- nano texture in injection

molded polymer

3D Texturing Machine

18

3D Laser Micromachining and Texturing Machine Picosecond pulsed laser, 5 axes + galvo Scanner

Tiling of Surface

19

Step and Scan Approach

Texture Generation

20

Dimple patterns with a specific density are generated

3D texturing test

21

Result

22

Functional surface texture

Marked outlines of the tiles

Tiles visible due to the regular dimple packing

Texturing Mirror Cup Mould

23

•  Demonstrator: Injection mold for car mirror cap

•  Goal: obtain a super-hydrophobic effect

FP7 project Nanoclean

Tiling - Meshing

24

CAD generated STL surface description

Remeshed surface

Mold texturing

25

Injection molded mirror cups

26

FP7 Project APPOLO

27

•  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)

28

•  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

30

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

31

32

Max Groenendijk Lightmotif B.V.

Pantheon 12 7521 PR Enschede

Tel: +31 (0)53 4500840 max.groenendijk@lightmotif.nl

www.lightmotif.nl

Thank you for your attention