BM1 Process

(1)

Extrusion Blow

-

_-

Moulding:

_Moulding:

The Process

(2)

Dept. Polymer Engineering

University of Minho

Applications

(3)

Extrusion based process

Hopper

Control

panel

Plasticising unit

Extrusion

die

Mould and

clamping unit

(4)

Extrusion based process

(5)

Extrusion based process

(6)

Extrusion based process

(7)

Extrusion based process

(8)

Extrusion based process

(9)

Extrusion based process

(10)

Extrusion based process:

(11)

Extrusion based process:

(12)

Extrusion based process:

Extrusion based process: effect of sag and

effect of sag and

extrudate

swell

1 - swell and no sag

2 - sag and no swell

3 – sag plus swell

(13)

Extrusion based process:

(14)

Extrusion based process:

(15)

Extrusion based process:

(16)

Extrusion based process:

transversal

pa

rison

thickness

programming

(17)

Extrusion based process:

Extrusion based process: extrusion with accumulator

extrusion with accumulator

(18)

Extrusion based process:

(19)

Extrusion based process:

(20)

Extrusion based process:

Extrusion based process: moulds

moulds

1

2

3

4 Types of ventilation systems

Capacity (l) Slit depth (mm)

>5 0.01-0.02

5-10 0.02-0.03

10-30 0.03-0.04

30-100 0.04-0.10

100-500 0.10-0.30

(21)

Extrusion based process:

Extrusion based process: moulds

moulds

(22)

Extrusion based process:

Extrusion based process: moulds

moulds

Inflation

with needle

(23)

Extrusion based process:

Extrusion based process: moulds

moulds

Cooling system:

• Channels diameter (d):

_{6 ≤ d ≤ 20 mm}

• Length: as short as possible (

T

_exit

-T

_entrance

_≤5ºC

)

• Reduced number of curve zones

• Distance channel-cavity surface:

d

(24)

Extrusion based process:

Extrusion based process: co

co-

-extrusion

extrusion

Permeability coefficients

Prices (relative to PVC)

HDPE

Adhesive

PA

Recycled HDPE

(25)

Extrusion based process:

(26)

Injection moulding based process

(27)

Injection moulding based process

(28)

Injection moulding based process

Advantages

(29)

Injection moulding based process:

designing pre-

designing pre

-forms

forms

• Espessuras tão pequenas

quanto possível

• Razões de sopro elevadas

• Machos cónicos (conicidade

mínima de 0.5º)

• Variações de espessura por

maquinação da cavidade

• Machos cilíndricos

• Variações de espessura

por maquinação do macho

(30)

Injection moulding based process:

sequence for designing

pre

-

forms

1 – Desenho do contentor (conhecido) e do macho (diâmetro e

inclinação conhecidos)

2 – Selecção das secções transversais a dimensionar

3 – Determinação da espessura da pré-forma (balanço mássico)

nas secções seleccionadas no passo 2

4 – Representação das espessuras determinadas no passo 3 no

desenho

5 – Atenuação de transições bruscas de espessura

6 – Cálculo do volume da pré-forma

7 – Repetição dos passos 5 e 6 até se obter um volume de

pré-forma semelhante ao do contentor

(31)

Stretch blow moulding

Injection moulding

of the pre-form

Stretching

and blowing

Ejection of

the bottle

(32)

Stretch blow moulding

(33)

Stretch blow moulding

(34)

Stretch blow moulding

(35)

Stretch blow moulding:

sequence of stretch and blowing

Wang et al., 1997

(36)

Stretch blow moulding:

sequence of stretch and blowing

Wang et al., 1997

(37)

Stretch blow moulding:

(38)

Stretch blow moulding:

(39)

Carbonated drinks:

Carbonated drinks: permeability (CO

permeability (CO

₂

)

Maximise ratio volume / surface area

Geometry

(40)

Stretch blow moulding:

typical processing parameters

(41)

Stretch blow moulding:

crystallisation kinetics

Crystals cannot

form: molecules

are too sluggish

Crystals cannot

exist: molecules

are too energetic

Glassy

state

Rubbery

state

Melt

state

Temperature (ºC)

60

65

250

255

(42)

Stretch blow moulding:

(43)

Stretch blow moulding:

(44)

Stretch blow moulding:

two stages versus one stage process

Advantages

Disadvantages

• Higher production rates

• Better pre-form temperature control

• Simpler bottle production (no need of

know-how on polymer processing )

• Higher global energy

consumption

(45)

Extrusion Blow

-

_-

Moulding:

_Moulding:

Non

(46)

Non

(47)

Non

-

conventional techniques:

3D technique

Battenfeld

Fischer

(48)

3D Technique:

3D Technique: X

X-

-Y mould

Y mould

Placo

, Ltd

Parison

Cavity

(49)

Placo

, Ltd

3D Technique:

(50)

3D Technique:

3D Technique: mould with vacuum

mould with vacuum

Battenfeld

(51)

Pre

-

blowing and moulds with moveable parts

Double

walled

container

(52)

Dept. Polymer Engineering University of Minho

Hollow

container with

re-entrant zone

Pre

(53)

Cycle time

Sequential co

-

extrusion

Rigid

Flexible

(54)

Sequential co

-

extrusion

Battenfeld

Fischer

Extruder 1

Extruder 2

Accumulator 1

Accumulator 2

Die flow channel 2

Die flow channel 1

(55)

Pressblower