Metals Polymers Ceramics Composites Classification of Materials.
Laser Cutting of Composites and Ceramics - AILU · Laser Cutting of Composites and Ceramics Laser...
Transcript of Laser Cutting of Composites and Ceramics - AILU · Laser Cutting of Composites and Ceramics Laser...
Copyright 2008, GSI Group Inc.AILU
December 3, 2008
Laser Cutting of Laser Cutting of
Composites and CeramicsComposites and Ceramics
Laser processing of polymer, metal and ceramic compositesLaser processing of polymer, metal and ceramic composites
Wednesday 3 December 2008Wednesday 3 December 2008
RollsRolls--Royce Factory of the Future within the Advanced Manufacturing Royce Factory of the Future within the Advanced Manufacturing
Research Centre (AMRC) with Boeing, Rotherham.Research Centre (AMRC) with Boeing, Rotherham.
Dr. Mo Naeem, GSI Group, Dr. Mo Naeem, GSI Group,
Laser Division, RugbyLaser Division, Rugby
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Dr. Mohammed Naeem is Materials Process Development Group
Leader. He received an MTech degree in metallurgical quality control
from Brunel University in 1981 and a Ph.D. in glass fibre composites
from Loughborough University of Technology in 1985. He has over 20
years of experience in the support of industrial lasers with GSI Group,
Laser Division and has published over 160 papers on laser material
processing. He has previously served as Materials Processing
Manager and held several Important Engineering Development roles.
Brief BiographyBrief Biography
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Lasers Precision Motion Laser Systems
GSI GroupGSI Group
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OutlineOutline
• Introduction
• Laser processing
–Polymer based composites
–Metal based composites
–Ceramics
–Silicon wafers
• Summary
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Composite materialsComposite materials
• A typical composite material is a system of materials composing of two or materials (mixed and bonded)
• Generally a composite material is composed of reinforcement (fibers, particles, flakes and/ or fillers) embedded in a matrix (polymers, metals or
ceramics).
Fiber Filler Flake Particulate Random
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Benefits of compositesBenefits of composites• Light weight
• High strength to- weight ratio
• Surface properties
– Corrosion resistance
– Weather resistance
– Tailored surface finish
• Thermal properties
– Low thermal conductivity
– Low coefficient of thermal expansion
• Electrical property
– Non magnetic
– Rader transparency
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ApplicationsApplications
Aerospace, Airbus (A380)
Automotive
The big DRIVE in automotive is from F1
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Laser machining of compositesLaser machining of composites
• Machining of composite materials often poses challenge, particularly for
fine profiles and counters and for hybrid laminates consisting of two or more vastly dissimilar materials.
• Conventional approaches used for composites, such as water- jet machining are not always sufficient.
• Laser machining of composites may offer a solution to some of these problems, although the laser- material interactions are not well understood.
• Typical machining involves:
– Cutting
– Drilling
– Milling
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A range of industrial lasers are currently available for laser material processing including polymer, metal and ceramic based composites.
100nm 400nm 10,600 CO2700nm1,064nm
Nd: YAG
532nm
Nd: YAG (x2)355nm
Nd: YAG (x3)266nm
Nd: YAG (x4)
157-351
Excimer lasers
1,030nm Disc laser
1,070-1,055nm Fiber lasers
Ultra- Violet
(UV)
VisibleInfra- Red
(IR)
Laser TypesLaser Types
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Laser Choice?Laser Choice?
Currently CO2 and Nd: YAG dominate the laser material processing market
CO2 Laser (10.6um)
• Higher average power
• Lower capital and
operating cost
• Less expensive safety
precautions with CO2
wavelength
Nd: YAG Laser (1.06um)
• Fiber optic delivery
• Easy beam alignment, beam
switching and beam shearing
• Less floor space with laser and beam delivery
• Good with highly reflectively material (i.e. aluminum based alloys
etc.
• High peak powers with high energy per pulse
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Mirror DeliveryMirror DeliveryMirror Delivery
CO2 laser, 10.6µm wavelength
Laser Workpiece
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Fiber DeliveryFiber Delivery
Laser
Laser
Workpiece
Workpiece
Timeshare/Energy share Fiber System
Single Fiber System
Nd: YAG laser, 1.06µm wavelength
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Two- Way Timeshare
Luminator FibersLuminator Fibers
Back reflection protection
patented technology
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A full range of welding ,and cutting focus heads
LuminatorLuminator™™ Beam DeliveryBeam Delivery
Safely weld, Drill and cut aluminum, ceramic
and other reflective alloys at 90º to workpiece
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Fiber DeliveryFiber DeliveryFiber Delivery
Single Fiber System
s = fiber dia. (focus fl/recoll fl)
Spot size (s)
focus lensrecoll lens
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Scanner OptionsScanner Options
• The near diffraction limited beams of new laser sources (fiber, disc) make scan head delivery an ideal option.
• Features
– Latest LightningTM Digital Scanner
Technology from GSI
• High dynamic performance and
processing speeds
• Unsurpassed in beam speed and accuracy.
– to be tuned to specific applications Digital control electronics enables
scanner dynamics.
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FL Galvo Head FL Galvo Head
Spot size and size of image field determined by:
• Focal length of collimating lens
• Focal length of Scan lens
• Choice of Scan Head
• Some Options
10µm spot - field 37mm x37mm
50µm spot – field 190mm x 190mm
200µm spot – field 290mm x 290mm
Larger spot possible by
defocusing
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Remote Processing Remote Processing
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Laser Cutting (advantages)Laser Cutting (advantages)
• Laser beam produces a spot of intense heat energy which can offer:– Narrow kerf widths with straight edges
– Very little heat affected zone adjacent to the cut edge
– Minimum heat input resulting in minimal distortion
– possible to cut/drill very fine features
• Since light exerts no force on the work piece, lasers are non-contact tools which means:– No mechanical distortion of the work piece
– No cutting tool wear, maintenance or replacement
– Ability to cut material regardless of their hardness
– Considerably less noise compared with water jet, plasma and mechanical techniques
• Additionally, the beam of light from the laser has a high degree of
control and flexibility
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Laser cutting (disadvantages)Laser cutting (disadvantages)
• High capital cost relative to other techniques (however, operating costs are lower than many other techniques)
• Microcracking at the cut edge may occur in some materials (i.e. engineering ceramics etc)
• Toxic fumes are generated from laser cutting of some materials (i.e. plastics composites etc)
• Especial eye wear and enclosed working enclosures
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Laser cutting mechanismLaser cutting mechanism
The beam penetrates into the kerf (a little is reflected from the materialsurface) and some passes straight through. A melt- front is generatedsupporting the molten material which is subsequently blown away out of the kerf with an assist gas.
A particular characteristic of laser cut is the formation ofStriations on the cut edge. These striations play an important partin laser cutting as they effectively control the edge roughness.
Typical assist gases are:OxygenArgon
NitrogenAir
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Schematic of cutting nozzle Schematic of cutting nozzle
arrangement arrangement
• The cutting nozzle nozzle is very important part of the
cutting machine. The cut quality and reproducibility
are governed by the design of the cutting nozzle.
Basically the nozzle consists off:
• Focussing lens • Assist gas chamber
• Nozzle tip • In some cases the
nozzle also have height
sensor (auto focus head)
TTL ILLUMINATION
CAMERA
ADJUSTABLE MIRROR
RECOLL LENS
FINE FOCUS ADJUSTMENT
COAXIAL GAS FLOW
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Processing dataProcessing data
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Polymer compositesPolymer composites
• In general the results show:
– The fibre type had a significant influence on the cut quality, carbon reinforced materials proving to more difficult to cut
– The main problem with the carbon fibre reinforced composites was fibre/resin separation.
– The effect became more severe as the thickness of the composite increased.
– For glass and aramid reinforced composites, less separation between the fibre and resin was observed but the cut edges were still characterised by carbon deposits.
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Carbon fibre compositeCarbon fibre composite
• Laser cut edge on carbon fiber (PEEK APC2) plastic composite
(0.2mm thick) showing protrusion of carbon fibers
• CO2 laser cutting conditions:
– Power: 500W
– Speed 4.5 m/min
– Assist gas: Air, 4 bar
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Carbon fibre compositeCarbon fibre composite
• Example of ring cut in carbon fiber/PEEK resin 2mm thick by CO2 laser cutting.
• Laser conditions:
– Power: 950 W (pulsed)
– Speed: 1m/min
– Assist gas: Nitrogen, 4bar
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Carbon compositeCarbon composite
1mm diameter trepanned hole
120µm percussion drilled hole
Entry
Exit
Low power pulsed Nd: YAG laser
Nitrogen assist gas
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Polymer composites (Summary)Polymer composites (Summary)
• Work carried out at GSI and at other institutes have shown that:
• CO2 laser because of its wavelength(10.6um) is best suited for polymer composite cutting, however the cut quality is not very good:
– separation between the matrix and the fibres
– Carbon deposit on the cut edge
– Cutting process produces hazardous by- products
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Ceramic materialsCeramic materials
• Ceramic and its based composites can be shaped using laser beam either by laser scribing or machining.
– Scribing is carried out at fast cutting speed (10-15m/min) to weaken the the ceramic, which is subsequently broken off.
– It is also possible to produce through- section cuts but at much
slower speeds. Both CO2 and Nd: YAG lasers are suitable for for these applications.
– Some ceramic (SI3N4 and AlC) tend to crack due to poor thermal shock. The cracking can be reduced by pre- and post heating of the
sample (typically up to 500deg C)
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Silicon nitrideSilicon nitride
Processing Parameters:
• Pulsed Nd: YAG laser
• Speed: 0.75m/min
• Assist gas: Nitrogen (4 bar)
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0.6mm thick Alumina (99.6%)0.6mm thick Alumina (99.6%)
Percussion drilled (50µm dia. hole)
SM 100W Fiber laser
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Metal matrix compositesMetal matrix composites
• Work carried so far have shown that two distinct modes of behaviour in laser cutting of metal matrix composites:
– One appears to be where the composites behave effectively as
metals and other where fibre and resin separation occurs similar to to carbon fibre polymer composite.
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Metal matrix compositeMetal matrix composite
• 2mm thick Al-Li alloy reinforced with 20% (wt) SiC particulate
– Pulsed Nd: YAG laser
– Assist gas: N2 @ 10bar
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Metal matrix compositeMetal matrix composite
• 1mm thick Ti-Al- 4v alloy with SiC fibre
– Pulsed Nd: YAG laser
– Assist gas: N2 @ 10bar
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SummarySummary
• CO2 laser is best suited for cutting polymer composite materials.
• Both CO2 and Nd: YAG can be used for cutting ceramic and metal based composite material.
• CO2 laser cutting of polymer composites is dependent upon the fibrereinforcement and the thickness of composite.
• For carbon fibre reinforced composites it is difficult to achieve cuts in material thickness over 4mm. In addition, separation of fibre and the resin occurs.
• Cutting of ceramic materials is affected by cracking caused by thermal shock. Use of pre/post heating can reduce this problem but some microcracking still occurs.
• In conclusion composite materials can be cut by using laser but the quality is not good as the water jet cutting.
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Silicon WafersSilicon Wafers
• Silicon wafers are conventionally diced off by a thin diamond blade into individual IC chip, before they are packaged. The problems encountered in blade dicing include chipping, kerfs-loss and low productivity.
• Currently green wavelength (frequency doubled) and micro jet arebeen used but both of these processes are slow and expensive to operate.
• Milliseconds low power pulsed Nd: YAG lasers and high beam quality continuous wave fiber lasers are being used to cut thesematerials but the cut quality is poor i.e. micro cracking due toexcessive heat input, which can lead to failure of some components during process steps and associated reduction in yields.. The length of micro cracks can range from 15µm to 100µm depending on the laser source being used.
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100W SM Fiber laser100W SM Fiber laser
400uµm thick polycrystalline silicon material, cutting speed > 4m/min showing very good edge
quality and no sign of any microcracking
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SM Fiber laser with SM Fiber laser with
modulated outputmodulated output
1.8mm thick polycrystalline silicon material, cutting speed >0.2mm, showing slight resolidified molten material at bottom of the cut, but
no sign of any micro cracks
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Pulsed Nd: YAG LaserPulsed Nd: YAG Laser
1.4mm thick polycrystalline silicon material, cutting speed
>0.3m/min, very smooth cut edge and no sign of any micro cracks
2mm thick polycrystalline silicon
material, cutting speed >0.15m/min, very smooth cut edge and no sign of
any micro cracks
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Pulsed Nd: YAG laserPulsed Nd: YAG laser
Percussion drilled in 2mm thick polycrystalline
silicon material
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Dr Mohammed Naeem
Laser Material Processing Development Manager
GSI Group Ltd, Laser Division
Cosford Lane, Rugby, Warwickshire, CV21 1QN, UK
Telephone (Direct Dial) : +44 (0)1788 517848
Telephone (Switchboard): +44 (0)1788 537075
Local Fax: +44 (0)1788 532617
Email: [email protected]
www.gsiglasers.com