plastic welding - design for laser manufacture - inspiring

© Laserline GmbH, Germany 1

Plastic WeldingPlastic Welding

with Diode Lasers with Diode Lasers

June 2005June 2005

Laserline GmbH ! Muelheim-Kaerlich ! Germany

www.laserline.de


Characteristics of Diode Laser Characteristics of Diode Laser

Direct diode laser on robot in production. Photo: Toyota

Advantages of Diode Lasers

1-step quick-welding

Flexible, any desired welding contour

Non-contact, fluff-free

Easily automated, high process stability

Low thermal and mechanical stress

“Top-Hat”-beam profile w/o intensity peaks

Applications

Gas-/fluid proof containers, electronic-

/sensor-housings, automotive parts, etc.


Plastic Welding with Diode Lasers Plastic Welding with Diode Lasers

Joining of Plastics with Diode Laser

" An Industrially Proven Process !

Content

Basics

Types of Welding Processes

Joining Techniques

Examples

Outlook


Welding of Plastic: PrincipleWelding of Plastic: Principle

Laser Beam

F

translucent

absorptive

Weld-Seam

F

Movement

Direction

Laser Beam Transmits Top Shell

Absorption in the Welding Zone

Bottom Shell

Melting of Both Parts by Heat Convection

Invisible Weld-Seam

No Damage to the Surface


Polymers for Plastic Welding

Thermoplastics (Amorphous or Partially

Crystalline) but not Duroplastics or Elastomeres

Overlapping Melting-Temperature

Comparable Melt Behaviour (Polarity etc.)

Transmission / Absorption Characteristics for

Laser Wavelength: One Transparent, One

Absorbing Layer

Mechanisms of Connection

Intermolecular Forces Between Molecule Chains

Mechanical Attachment by Macro-Molecules That

Diffuse from one Part to the Other

Welding of Plastic: BasicsWelding of Plastic: Basics


Parameters " Welding System

Laser: beam forming, wavelength, optical power,

spot size, energy distribution

Machine concept: laser, manipulating system

(positioning), cooling unit, electrics, other external

components

Parameters " Parts

Combination of thermoplastics (thermal, mechanical

and optical properties " additives!)

Type and positioning of weld seam, thickness, parts

design

Parameters " Process

Welding speed, cycle time, absorption of heat /

reaction time

Weld Results

Width of the seam

(HAZ)

Optical results

Resulting strength

Internal strains

Main ParametersMain Parameters



Source: VDI Kunststofftechnik/BASF



Laser

translucent

absorptive

Weld Joint

F

F

“Transmission welding”

Quality of weld depends on:

• Welding pressure

• Flatness of parts-surface

• Thickness of transparent welding

partner


„Setting Path“„Visible Notch“

F

F

Laser


Typical Part Design with Process Control by Welding Path


Plastic Welding: Typical DataPlastic Welding: Typical Data

10

100

1000

10 100 1000 10000

Power [W]

Be

am

qu

ali

ty [

mm

mra

d]

Hartlöten

Schneiden

Kunststoffs

chweißen

TiefschweißenLötenSchweißen

Hybridschweißen

Härten

Auftragsschweißen

10

100

1000

10 100 1000 10000

Power [W]

Be

am

qu

ali

ty [

mm

mra

d]

Plastic

Welding

Electronics housings

Laser

DioScan, Direct, Fiber-Coupled and

Multi-Diode Lasers

Power

50 W to 800 W

Beam quality

< 150 mm mrad

Spot dimensions

0.5 to 5 mm

Material

- Thermoplaste

- Thermoplastische Elastomere (TPE)


Diode Laser Types for Plastic WeldingDiode Laser Types for Plastic Welding

Fiber-coupled diode laser LDM

Multi diode laser system (100 diode laser sources)

DioScan F

Direct diode laser, LDL 40


DioScan: beam scanner with PC or stand-alone control,

scanner software and integration for plastic welding

Optics with different beam dimensions and working distances

1-inch or 2-inch optics

Ring focus optics for simultaneous welding of circular seams

Circumferential weld optics for welding of tubes

Pyrometer and CCD camera for process monitoring

PlasticPlastic WeldingWelding: : OptionsOptions


Variants of Welding ProcessesVariants of Welding Processes

I. Quasi-Simultaneous Welding (QS):

Uniform, step-by-step heating of the

weld zone

Rotation symmetric parts or any

desired 2D-contour

II. Contour Welding:

One-step-welding process

Any desired geometry, 3D contour


Special Variants ISpecial Variants I

Multi-Laser-System:

Rotation symmetric parts

Uniform, simultaneous heating of

different weld zones

Shortest cycle time

Cost reduction due to less process

stations


Special Variants IISpecial Variants II

Simultaneous Welding:

Uniform, simultaneous Heating of

the Weld Zone

No internal strains, any part

geometry

Reduced cycle time

Low flexibility, high complexity


Special Variants IIISpecial Variants III

Special focusing optics for circular focus geometry

„AXICON“

Laser-light-cable

Laser beam

Rotation symmetric part

Parabolic mirror

Circular focusing optics

Collimating optics

Scheme: Special Optics


Systems ASystems Advantagesdvantages

Spot Welds

Contour Welds

Multi-Spot Welds

Step Welds

Weld Geometry \ Laser Direct & Fiber-Coupled Scan-System Multi Diode

(QS) (simultaneous)


I. System Concept: Multi-LaserI. System Concept: Multi-Laser

100-Laser-System

Multi-Laser-System

Redundant system

Shortest cycle time

Applications

• Structures

• Foils

• Rotation symmetrical partsTwin-Laser-System


II. System Concept: QS-WeldingII. System Concept: QS-Welding

Part holder

DioScan Circular table

Laser safety feature

DioScan

Simple manipulation system

Laser safety box

Short cycle time

Application

Sensors, electronic housings,

etc.


Ultrasonic• 1-Step-Process

• Mechanical Force Transmission

• US-Frequency in Weld Zone

• All Thermoplastics

Glueing• Multi-Step-Process

• Glue Application through Nozzles

• Most Plastics

Heat Plate

• 1-Step-Process

• Global Heating through Heat Plates


Joining Techniques - ComparisonJoining Techniques - Comparison

Laser• 1-Step-Process

• No Touch

• IR-Radiation in Weld Zone

• All Thermoplastics (optically suited)

Vibration• 1-Step-Process

• Mechanical Force Transmission

• Vibration Forces in Weld Zone



0

50

100

Availability

Flexibility

Joint-qualityGap-bridging

Part damage

Laser

US

VIB

Gluing

Joining Techniques - ComparisonJoining Techniques - Comparison

Diode Laser

• Highest welding quality (visible joints, fluff free)

• Highly flexible (robot, axis-system,

quasi-simultaneous welding)

• Availability 99.5 %

• Gap-bridging

• Wear-resistant tool

Scan system

Direct diode

laser


Requirements from IndustryRequirements from Industry

Requirements• Failed parts 0 ppm

• Gap bridging

• Gas proof

• No damage to the part

• No fluff in weld

• Any desired contour

• Sensitive electronic parts

Characteristics• Process control

• Check of melting path

• Endless weld-seams

• Non-contact

• No vibrations

• Maximum flexibility

• Local heat input

Vibration

Gluing

Laser

Ultrasonic

Heat Plate


Weld Seam Geometry YAG vs. Diode LaserWeld Seam Geometry YAG vs. Diode Laser

--++Large area weldsPlastic layers, plate material, foils

-+++< 1.5 mmLarge housings, broad area connections,contour welding

+++++0.25 ...1.5 mmSensors, small housings, welding with settingpath

++++< 0.25 mm.!-Structures, etc.

Nd:YAGDiodeWeld seam dimensions. Advantages anddisadvantages of the different systems

Diode Laser

Top-hat beam profile "

Homogeneous weld over

entire width of weld seam

Good weld seam control

Ideal for welds > 0.25 mm

width and larger areas

Nd:YAG Laser

Gauß beam profile:

High central intensity limits

max. power

Higher risk of parts damage

Less homogeneous weld

Ideal for micro structures

< 0.25 mm width

w = weld zone

ww

Diode Laser Nd:YAG Laser


Influence of Power on ProductivityInfluence of Power on Productivity

influence of laser power, material: PA6,

weld seam length: 250mm

0

5

10

15

20

25

50 150 250 350

laser power [W]

tota

l ti

me f

or

weld

[s]

0

1

2

3

4

5

sp

eed

[m

/s]

Potenziell (Ges.-Zeit [s])

Polynomisch (v [m/s])

time for weld

scan speed

Quasi simultaneous welding

Almost constant path

energy without damage

to components

Higher power and scan

speed result in reduced

welding time

High flexibility AND

high productivity


Laser control by scan software

Graphical view of settings

User-/ Operator surface

Special mode for easy operation

(e. g. operator mode for 3-shift

production)

Contour flexibility, import of dxf, wmf,

bmp, plt, ...

Scan SoftwareScan Software


Prozess Prozess MonitoringMonitoring

SoftwareThermal OpticalMechanical Visual

Setting path

sensor

Back reflection

diagnoctics

Pyrometer Frame-Grabber CCD-Camera

Alignment

beam


ExamplesExamples: Automotive : Automotive IndustryIndustry

Schaltbox

Air Flow Sensor

Car Key


ExamplesExamples: Automotive: Automotive Industry Industry

Electronic Housings

Automatic Gear Box


Plastic Welding: ExamplesPlastic Welding: Examples

Mats from plastic material

Liquid pouring device

Invisible weld seam in PMMA

Weld of foam on plastics


Integration in a system with round switch tablePhoto

: Laserq

uip

ment

Example: Magnetic Sensor Example: Magnetic Sensor

Tyco Electronics AMP GmbH

Welding seam


LDL 40-100 - Direct Diode Laser

Contour Welding

Opaque Material

Example: Movement SensorExample: Movement Sensor

Source: Laserquipment


Example: Hydraulic TankExample: Hydraulic Tank

Source: branson

Welding of hydraulic tanks

DioScan 200

Result:

Excellent welding seam

Single step process

Highest process-stability

Non-contact process

No fluff development


ExampleExample: : Ostomy BagsOstomy Bags

LDF 600-300

Fiber-Coupled Diode Laser

Medical Industry

Contour welding of concentric

Circles

Soft-to-soft welding


Medical Industry

Contour welding of

transparent material

“Clear weld” (1)

Black absorbing foil (2)

Example: Filter ElementExample: Filter Element

Source: Leister

(1)

(2)


Reference Customers (selection)Reference Customers (selection)

Others

- Boeing

- Colbond

- Erlas

- Philips

- Thyssen

- TRW

Metal Welding

Plastic Welding

Pump-Module for Fiber-Laser

Automotive

- Bosch

- Bremi

- Daimler Chrysler

- Geigertechnik

- Grau

- Mendiguren

- Siemens VDO

- VAW

Metal Welding

Plastic Welding

Sensors

Electrical-MechanicalComponents

Valves

Housings


OutlookOutlook

Plastic Welding with Diode Laser

• Highest Quality-Requirement for

Joining Techniques in Automotive

Industry

• Easily Integrated in Full-Automation

Systems

• Customers-Specific Solutions

plastic welding - design for laser manufacture - inspiring

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