palestra 3 - fabricação de moldes por micro-usinagem

© WZL/Fraunhofer IPT© WZL/Fraunhofer IPT

Manufacturing of micro-moulds

Benedikt Gellissen

Fraunhofer Institute for Production Technology IPT

International Seminar: Application of new technologies in the metal mechanic sector

Joinville, Brazil, September 2011

© WZL/Fraunhofer IPT

Economic Developments in MST

91 93 95 98 00

93 95 97 99

94 96 98 00

123456789 billion US$

2468

10121416 billion US$

2

4

6

8

10

12 billion US$

510152025303540 billion US$

96 97 98 99 00 01 02

Batelle (1990) SEMI (1995)

SPC (1994) NEXUS (1998)

95 97 99

94 96 98 00

Source: NEXUS, VDI VDE-IT

The booming of microsystem technology (MST):

- Main focus on industries like life science, IT, bio-and sensor technology

- Annual growth of 18% from 1996 to 2002

- Estimated growth of the market from 2002 to 2005 of 28 to 65 billion US$


Economic and Technical Developments

20

40

60

80

100

120

140

160

180

90 91 92 93 94 95 96 97 98 99USA (880)Japan (445)Germany (378)

Number of patent registrations

23 Fraunhofer Gesellschaft21 Robert Bosch GmbH16 Institut für Mikrotechnik Mainz GmbH15 Siemens AG

e.g.

Patent analysis of MSTfor microPRO Study in 2002:

- Based on the World Patent Index

- The following terms were taken under consideration: MST, Micro -mechanic, -optic, -fluidic, -assembly, UP- and micro machining

- 29.7% of the patent categories come from the field of plastics processing

Indications of upcoming mass production


International comparison - microPRO Study

§ Company activities were focused on optics, electronics production and the production of tools and machine tools

§ Trend towards integration of miniaturized systems into new (mass) products§ Development of extremely downscaled machine tools and complete assembly systems

Japan, Taiwan, Singapore

§ Strong influence by electronics production and semiconductor technology§ High process automation demanded

(due to prevailing high quantities in the above named sectors)§ Future market segments are seen in medical engineering, bio-technology and

in electro-optical products

USA

§ Predominantly affiliation of enterprises to mechanical engineering and precision engineering§ Industrially practiced miniaturization is closely connected to the watch industry § Technical know-how is currently used to open up new market segments like

information and communications technology

Switzerland


Summary of mikroPRO Study

§ Numerous applications of micro manufacturing technologies in variousindustrial sectors

§ Broad basic research - some excellent results in single manufacturing technologies

§ There are deficits in the transfer of the technologies into real products,partly due to- low industrial maturity of the manufacturing technologies

(process stability)- lack of technological knowledge for the design and development

of new products (manufacturing specific design, technology limits,design rules)

- limited accessible knowledge of industrial product and processrequirements


Typical branches –MST are found in different branches with the tendency for mass production

- Sensor technology- Optical elementsfor interior and exterior

- Micro mechanical devices- ...

- Medical technology- Biotechnology- Techniques for analysis- ...

- Optical data transfer and coupling

- Display technology- ...

Source: Cooke Corp., microparts, Euronano

Automotive industry Life sciences Telecommunication


Due to developments in the industry -MST is still a chance for mould and die makers

Example of powder injection molding products; gear (MIM), (Source: IFAM)

Measuring instrument for alcohol (Source: IMT, TU Braunschweig)

Micro channel

Detectioncell

Micro pumpsBioreactor

Micro Electro-Mechanical Systems (MEMS)

Precision Engineering

Example of micro cast products (Source: FZK)

10 µm

(Source: Grundig)Test piece and human hair structured with dicing blades

Micro-structuring

(Source: DISCO Corp.)

Mic

ro M

ould

Mak

ing


Focus of this presentation –Conventional Technologies in MST

Chip removalDiamond Carbide

EDMWire-EDM Sink-EDM

Workpiece material

NickelBrass

AluminiumPlastics

SteelCeramicsGraphite

Metals(Ceramics)

Metals(Ceramics)

MetalsGraphiteCeramics

Lateral structures 10 - 1000 µm 10 - 1000 µm 20 - 50 µm 20 - 40 µm 5 - 1000 µm

Aspect ratio 10 - 50 2 - 10 25 - 80 10 - 25 10 - 100

Geometricfreedom ++ ++ + + ++

Surface quality Ra

0.01 µm 0.3 µm 0.04 – 0.06 µm 0.2 – 0.4 µm 0.1 – 1.3 µm

LaseringNd:YAG

200µm200µm 200mm700mm200µm


100 50 25 10 5

50

25

10

5

1

200

EDM

Chip removal

Grinding

Laser

Silicon etching

Str

uct

ure

[µ

m]

Surface roughness Ra [nm]

LIGA

Production processes in MST –Compromises and alignment with the costumer product

planar freeforms

Complexity of geometry

Silicon etching (40%)

Chip removal (22%)

EDM (16%)

LIGA (11%)

Grinding (9%)

Source: IPA, ILT, IPT


Photolithography Etching of Silicon –Advantages are clearly visible but the limitations too

Source: Cranfield University, Zeiss

Silicon dioxidefilm to be etched

industrial wave length min. use of illuminate structure

1980 - 1986 436 nm 0.60 µm1986 - now 365 nm 0.35 µm1992 - now 248 nm 0.20 µm1998 - now 193 nm 0.15 µmR+D 157 nm 0.12 µmR+D 013 nm 0.08 µm


Sources: Scholz, Impella, Wikipedia.de, Fraunhofer IPT

Intracardial blood pump Micro fuel cellFacette mirror

Reflecting structures

Typical products –The requirements towards the products functionality is spread widely

Lab on a chip


Conventional Technologies in MST



Workpiece material

NickelBrass

AluminiumPlastics


Metals(Ceramics)

Metals(Ceramics)



Aspect ratio 10 - 50 2 - 10 25 - 80 10 - 25 10 - 100


Surface quality Ra

0.01 µm 0.3 µm 0.04 – 0.06 µm 0.2 – 0.4 µm 0.1 – 1.3 µm

LaseringNd:YAG

200µm200µm 200mm700mm200µm


Insert

Solution to date

- Complex fabrication and positioning of the three electrodes

Aim

- Direct fabrication of the inserts by 5-axis micro milling

Micro Clip for medical applications -detail of clip mechanism

Insert with electrodes

•

ƒ

‚Insert

Electrode

Electrode

Electrode

Challenges

- Steel mould insert- Micro free-form surfaces - Undercut of 54 µm

Micro Clip (Design)

Source: Zumtobel Staff


200 µm

Feature Awith undercut

Mould Insert (SEM image)

Feature A

Micro Clip (Mould Insert)

Source: Zumtobel Staff


Intracardiac pump systemfor patient-friendly andeconomic treatment of acute heart diseases< Replacement of heart-lung

machines via intrabody< No surgical intervention< On site placement in the

heart through the leg artery< Post operation heart

support for up to 7 days< Outer diameter of pump 4.0

and 6.4 mm respectively< Pump performance up to

4,5 l/min

Application -Intracardiac Pump System

Measurements: 3.55mm x 7.7mmMaterial: PEEKSource: Impella CardioSystems AG


Former process: Five axis milling of PEEK

Quelle: IBMT

<Single part manufacturing<High effort for manual finishing< Low reproducability

Recover® Technology: Manufacturing of Impeller


Former process: Five axis milling of PEEK

Now: Injection moulding

Quelle: IBMT

<Single part manufacturing<High effort for manual finishing< Low reproducability

<Batch production< Low effort for manual finishing<Extremely high reproducability

Recover® Technology: Manufacturing of Impeller

Source: Horst Scholz GmbH + Co. KG


Former process: Micro-EDM Now: Five axis micro milling

<High process knowledge< Two-step process<Effort for manual finishing

< 5 axis manufacturing necessary<One-step process

Manufacturing of Mould Inserts


Conventional Technologies in MST



Workpiece material

NickelBrass

AluminiumPlastics


Metals(Ceramics)

Metals(Ceramics)



Aspect ratio 10 - 50 2 - 10 25 - 80 10 - 25 10 - 100


Surface quality Ra

0.01 µm 0.3 µm 0.04 – 0.06 µm 0.2 – 0.4 µm 0.1 – 1.3 µm

LaseringNd:YAG

200µm200µm 200mm700mm200µm


UP-processes –Structures and processes strategies

Face milling

TurningUP-Planing

Fly Cutting


n Ultraprecision machine for the machining of large workpieces by means of diamond milling and planing

n Max. working area 1000 x 1000 x 200 mm³

n Rotary table (C-axis)

n Hydrostatic bearings for all axis (not realised in vertical direction)

n Two portal slides for either mass compensation or usage of two tools

n Equipped with standard NC controller

UP-planing-machine for large-scaled structured surfaces


ap

f

Manufacturedsurface

Vorschub

-

a

f

Tool shaft

Diamond tool

Vorschub

Cut directionxz xz

Spindle rotation

Tool

Part

Roughness

n Tools: mono crystalline diamond

n Structure size 3 µm, surface roughness 10 nm Ra

n Highest form accuracy

n Work pieces up to 1 x 1 m2

n High manufacturing times for big parts

Manufacturing technology for micro and nano structures

Fly cutting Planing


Fly-Cutting – Applications

2 mm 50 mm

100 mm

10 mm

100 µm10 mm

0,5 mm 0,5 mm

Masterstruktur einer Beleuchtungs-optik Element eines Retroreflektors

HeißprägewerkzeugMasterstruktur eines großflächigen Reflektors


Large area structuring with the fly-cutting process

n Long time machiningn Structure: triangular corner cubes (1 mm)n Size of workpiece: 400 x 400 mm2n Distance of cut: 6.15 kmn Machining time: 5.3 dn Machined at tangential feedn Investigation on tool wear

Machined master (CuNi18Zn20 400 x 400 mm2)Sample part with structure

2 mm


Hybrid optics

10 mm

Sinus curve-surface

Facet mirror

HybridFTS


Machine for the production of hybrid optics

Granite base plate

Height adjustment

Case

B-axis

Fast Tool

n Dynamic axis– Total weight 90 kg

– Moving mass 10 kg

– Max. acceleration 62 m/sec²

– Travel length of axis – Max. work piece diameter– Total weight – Dimensions

410 mm800 mm3.800 kg

1900x1500x1500

n MTC 410


Reflector surface

n Freeform surface

n Scaleable geometry

n Diameter = 20 mm

n Non-rotationally symmetric portion: 0,45 mm

n Data type: NURBS(Non Uniform Rational B-Splines)

Manufacturing requirements

n Harmonic tool path

n Very high frequency position control

NURBS-Mirror surface Simulated tool pathy

[mm

]

Brightness distribution

NC code correction

Light source

Freeform-mirror Projection

Source: OEC AG

Freeform reflectors - computable, but not to manufacture?

x [mm]


Summary –Limitation of UP Machining

Ultra precision machining with mono crystalline diamond tools

Recent developments < ultra precision machining of nonferrous materials by

turning, milling and fly cutting< extremely high surface quality of a few nanometers Ra< shape accuracy in the submicron range

Restrictions< machining of ferrous materials causes high wear< life time of nonferrous metals cavities

is not sufficient in many cases< galvanic process chain is time consuming, expansive

and with limited reproducibility

Galvanic layer separation There is a huge demand for flexible production technologies to machine wear resisted mould inlays


CompetitivenessPrecision Glass Molding vs. Alternative Manufacturing Technologie

Grinding and Polishing

– Oldest technology for glass optics manufacturing

– Large variety geometries possible

– Nearly all optical glasses machinable

– Highest accuracies obtainable

Conventional Molding

– Technology for mass production

– Non-isothermal

– Accuracies satisfying for lighting optics

– Limitation in glass material choice

– Geometric variability limited by mold manufacturing

Precision Glass Molding

– Technology for mass production

– Obtainable accuracy satisfying for imaging optics

– Isothermal process– Nearly all optical glass

moldable– Ceramic molds– Accuracies in the range l to l/5


Precision Glass Molding:An Integrative Approach

Optic Design

MoldedLens

Data Handling

FEMSimulation

Mold DesignMold

Manufact.Molding

Idea

n Optimization of the process sequence for precision glass molding towards higher efficiency and more complex optical elements

n Generation of an integrated approach for the data handling

Concept

n Consideration of each single process step including the different interfaces


Precision Glass Molding The Process

Source: Fraunhofer IPT

Tg

Time

Tem

pera

tur F

orce

Homogizing

ForceTemperatur

PressingHeating Cooling

Temperatur and force cycle

1. Loading andN2-purging

2. Heating of glassand mold

3. Pressing

N2 Gas

IR -lamps

F

N2 Gas

4. Cooling and unloading

Process cycle

Mold

Isothermal molding process leads to high accuracies!


An Integrative Approach:Data Handling

n Data flow (forward):– Optic design (IGES file)

– FE process simulation andNC code generation, both based on IGES file

– Mold manufacturing

– Molding

n Data flow (feedback)– Metrology data from mold

manufacturing to create adapted NC code

– Metrology data from molding to improve FE process simulation

Source: Zemax, Toshiba, ModuleWorks

Ideal data flow

Metrology

Data

Metrology Data


Tool making for Precision Glass Molding

Challenges

n High Accuracy (shape deviation < 1µm)

n Optical surface quality (Ra < 10 nm)

n Mold material: carbide (HV10: 2825 GPa, Density: 15,75 g/cm³)

Process

n Ultra precision grinding (resolution < 1nm, air guided spindle)

n Resin bonded grinding tools for ductile machining

n 4-axis process for freeform applications

Source: Faunhofer IPT


Precision Glass MoldingExamples

n Double sided condensor lens for homogenization of coherent (excimer lasers) or incoherent light sources (ultra high power lamps)

n Appr. 1800 single cavities with optical quality (1.2 mm in diameter)

5 mm10 mm


Machine set-up for ultrasonic assisted turning

ultrasonic tool system

HF-generator

monitor

dynamometer

amplifier

oszilloscope

capacitive sensor

adjustableclamping device

workpiece

personalcomputer

spindle

control unit


Comparison of Tool Wear in Diamond Cutting –Conventional Cutting versus Ultrasonic Assisted Cutting

material: X3 CrNiMoAl 13-8-2depth of cut: ap = 8 µmfeed: f = 5 µm

SVy~4 µm

rake facenose radius rε = 0,899mm

35µm

SVy~4 µm

rake facenose radius rε = 0,899mm

35µm

n Conventional cutting– cutting length < 50 m

n US-assisted cutting– cutting length > 5000 m


Ultrasonic Assisted Diamond Tools (40kHz) - The Principle and Advantages

n diamond tool is loaded with ultrasonic vibration in cutting direction

– Amplitude 1 µm

– Frequency 80 kHz

n reduction of effective contact duration and process forces

n better inflow of coolant

n reduction of friction between tool and chip

reduced tool wear

ductile cutting

bottomdead centre

top deadcentre

0

2

4

6 amplitude [µm]

-6

-4

-2

0 0,5 1,0 1,5 2,0 2,5 3,5

T

workpiecemovement

tool movement

Ta Te Ta

(Ta)

vc-rot

vrel > 01

vc-os

point of separation (Ta)point of entrance (Te)

period without contact

vrel = 0 vrel < 0 vrel > 0

contact time [µs]

contactpoint (Te)

vrel > 0 vrel = 0

contact

2 3 4 5 6

contact


Molds for micro optics manufacturing Concave and Convex Aspheres

Form deviation [nm]

-800

400600

-200

2000

-400-600

Radial Position [mm]-2-4 -3 -1 0 1 2 3 4

PV 144 nm

PV 204 nm

Form deviation [nm]

-300

-200

200

0

100

-2-4 -3 -1 0 1 2 3 4-5 5Radial Position [mm]

-100

n Manufacturing on Moore Nanotech 350 FG

n On machine measurement and compensation applied

n Shape accuracies on aspheres < 210 nm

n Tools with non controlled waviness


µ-Moulds – Process combinations for new ideasDemonstrator Mould by the Fraunhofer IPT


µ-Moulds – Process combinations for new ideas Demonstrator with optimized Top Surface – Microscope Image

burr formation


Your contact to Fraunhofer IPT

Dipl.-Ing. Benedikt Gellissen

Fraunhofer Institute for Production Technology IPTSteinbachstraße 17, 52074 AachenPhone: +49 241 89 04-256Fax: +49 241 89 04-6256Mail: [email protected]

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