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Emitter-Material – A complex system

Presenter: Marios Constantinou, M.Sc.

Professorship of Plastics Engineering

Technische Universität Chemnitz

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1. The infrared (IR) welding process

2. Interactions between emitter and material

3. Approach to the IR-welding of plastics

4. Summary

5. Outlook / Current research

Agenda

3

Time

Jo

inin

gp

ath

Joining path

The infrared (IR) welding process

Jo

inin

gp

ressu

re

Jo

inin

gp

ath

Time

I. Radiation

II. Changeover

III. Joining

III III III III

Process phases – IR welding

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Process comparison – Relevant parameters

IR-welding Hot plate welding

Emission behaviour - Emitter:

Type of emitter (short-, midwave)

Power of emitter

Emitter distance

Hot plate temperature

Absorption behaviour - Material:

Absorption

Reflection

Heat conduction

Heat conduction

Heating time Heating time

Joining pressure Joining pressure

Joining path Joining path

Hold phase Hold phase

The IR-welding process

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Medium-wave metal strip radiator

Surface temperature ≈ 750 - 850°C

Usual Components :

Aluminum housing

Ceramic carrier

Metal foil

MW

SW

Common infrared emitters used for the welding of plastics

Short-wave twin tube quartz glass radiator

Surface temperature ≈ 1800 - 2400°C

Usual Components :

Evacuated quartz glass tube

Gold reflector

Metal wire


6Source: Odelo

Source: Frimo Source: Frimo

Applications


Source: Frimo

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4. Summary


Agenda

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Main influences on emitter-material interactions

Type of emitter (SW, MW)

Emitter distance

Power of emitter

Emission behaviour of emitter Absorption behaviour of material

Material

Fillers (e.g. carbon black, glass

fibres)

Morphology of material

Emitter-material interactions

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Main influences on emitter-material interactions

Type of emitter (SW, MW)

Emitter distance

Power of emitter

Emission behaviour of emitter Absorption behaviour of material

Material

Fillers (e.g. carbon black, glass

fibres)

Morphology of material


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Emission behaviour – Influence of emitter type (PP-natural coloured)

MW: Required emitter distances are lower.

SW: Influence of distance changes is lower.Source: Diss Fuhrich, Technische Universität Chemnitz, 2013

MW

SW


Medium-wave

Short-wave

Me

ltla

ye

rth

ick

ne

ss

L0

[mm

]

Emitter distance x [mm]

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Emission behaviour of emitter/ Absorption behaviour of material

Near-surface absorption Volume absorption

T

xx

T

xx

Plastic partPlastic part Intensity decrease

Absorption spectrum of material results in emitter-material interactions.

Depth of optical penetration/ Absorption behaviour is depending on:

Wavelength of IR-radiation

Chemical composition of plastic

Fillers


Intensity decrease

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Layer thickness

Natural coloured Carbon black filled

MW

SWMW

SW

Radia

tion inte

nsity

Radia

tion inte

nsity

Absorption behaviour of material – Influence of fillers

Equal heating parameters (SW)


Layer thickness

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Carbon black and glass fibres cause a reduction of the heating time

Source: Diss Fuhrich, Technische Universität Chemnitz, 2013


Absorption behaviour of material (PA66) – Influence of fillers

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

0 5 10 15 20 25 30 35 40 45 50 55 60

Me

ltla

ye

rth

ick

ne

ss

L0

[mm

]

MW

Heating time tE [s]

Natural coloured

Black

GF natural coloured

GF black

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Carbon black leads to a change from volume to near-surface absorption


Absorption behaviour of material (PA66) – Influence of fillers

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

0 5 10 15 20 25 30 35 40 45 50 55 60

KW

Natural coloured

Black

GF natural coloured

GF black

Me

ltla

ye

rth

ick

ne

ss

L0

[mm

]

Heating time tE [s]

Source: Diss Fuhrich, Technische Universität Chemnitz, 2013

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Welding factor 1,0

SW

Structures of welded joints – PP-H natural coloured

MW

Welding factor 1,0

Failure behaviour of IR-welded natural coloured PP-H

in tensile creep test acc. to DVS 2203-4 (SW, joining

pressure = 0,25 N/mm², test duration = 1630 h)

Eq

ual

join

ing

pre

ss

ure

s


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Processing effects – Local fibre orientation

Material: PA66-CF20

Emitter: SW

Equal material/ equal heating parameters – Different fusion behaviour

Influence of fibre orientation

Near the gate (cutted edge)

Away from the gate (moulded edge)

Injection moulded sheet

4 mm

4 mm

3-layer-structure

(schematic)Gate

Flow direction of melt


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IR-Emitter

Injection moulded sheet (PA66 CF)

1 2 7 12 13

0

10

20

30

40

50

60

70

80

90

1 2 3 4 5 6 7 8 9 10 11 12 13

Tear

str

ength

[N/m

m²]

Sample [No.]

SW

MW

PA66 (unreinforced)

Processing effects – Global fibre orientation

Material: PA66-CF20

Emitter: SW, MW

Fusion behaviour is affected by the fibre orientations

Mechanical weld properties determined by fibre orientations


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4. Summary


Agenda

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IR-welding of plastics

1. Selection of emitter system (SW, MW)

Depends on part dimensions, radii, warpage, wall thicknesses etc.

2. Fusion tests on parts

Influence of fillers on heating times etc.

Determination of material resistance against thermal oxidation

Definition of emitter distance-heating time-combinations

3. Welding trials (optional)

Variation of process parameters, e.g. joining pressure, changeover time

Transfer of optimum parameters to production process

Part design Material

Initial input

Approach to the IR-welding of plastics

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4. Summary


Agenda

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Summary

Advantages of IR-welding

No physical contact to parts during heating phase (no material sticking, wear)

High flexibility in weld design

High degree of automation

High weld strengths possible

Without alternatives for specific applications made of technical/ fibre reinforced

plastics

IR-welding offers high potential e.g. for the joining of FRP

Challenging correlations require an accurate process planning

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4. Summary


Agenda

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Joining of hollow parts made of organic sheets – Motivation

Current research

State of the art: Flanged butt joint

CAMISMA backrest

Twin-O-Sheet sample

Objective: Overlap joint in hollowparts made of organic sheets

Advantages of overlap joints

Fibre orientation in direction of load path

Maximum utilisation of fibre orientation

Increased potential of light weight construction

by material savings possible

Source:

Johnson Controls

Source: LKT Erlangen

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Breaking force PA6-Matrix = 3,2 kN

Breaking force of overlap joint considerably higher than matrix value

Reinforcement by fibres along the joint plane is possible

Welding setup

Joining of hollow parts made of organic sheets – Results

0

2

4

6

8

10

12

14

16

Bre

ak

ing

forc

e[k

N]

Welded-

Flange

No

n-w

eld

ed

-

Org

anic

sh

ee

tP

A6-G

F4

6

We

lde

d-

Ove

rla

p

87 % 5 %

Current research

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Thanks for your attention!

Contact:

TU Chemnitz – Professorship of Plastics Engineering

Marios Constantinou

E-Mail: [email protected]

Tel.: +49 (0) 371-531 35461

www.kunststofftechnik-chemnitz.de

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