Package Evaluation Training 4 longtitudnal sealing

Principle of LS and SA sealing The Longitudinal Strip in Tetra Brik Aseptic system LS Strip Function has 3 main functions: 1 To prevent product absorption into the packaging material e

2 Evaluation – Visual inspection + Practical

3 Evaluation – Mechanical tear down + Practical

4 Evaluation – Red ink injection + Practical

5 Sample of the defect

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1 Principle of LS and SA sealing

The Longitudinal Strip in Tetra Brik Aseptic system

LS Strip Function

has 3 main functions:

1) To prevent product absorption into the packaging material

edge

2) To improve the gas barrier properties of the longitudinal

seal area

3) To strengthen the longitudinal seal

3) To strengthen the longitudinal seal

1 Principle of LS and SA sealing

LS Strip application - terminology

The strip applicator side (SA) of p pp ( ) the seal is where the strip (2) is attached to the packaging material by the strip applicator.

The SA is the side of the strip where the packaging material (3)

An air gap (4) is present in the middle of the seal.

1 Principle of LS and SA sealing

SA Sealing

The Operations are:

of packaging material is heated to melt the plastic layer either by hot air, or by induction heating.

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surface and pressed onto the packaging material using pressure rollers.

1 Principle of LS and SA sealing

LS Sealing

 The LS makes a tight tube of packaging material just prior to coming packaging material just prior to coming

in contact with the filling product

 The flat PM (strip on one edge), is guided into a tube form

 The edge without strip is heating (hot air or induction heating) by the longitudinal element.

 The heated edge meets the underlying unheated one and the two

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y g are pressed together between two rollers.

 This sealing is achieved between the inner and the outer surfaces of PM and between the strip and the inside of the tube

1 Principle of LS and SA sealing

Type of sealing system

1 Principle of LS/SA sealing

LS sealing component – Lower forming ring and LS

spring

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1 Principle of LS/SA sealing

LS sealing component – Spring Force

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1 Principle of LS/SA sealing

LS sealing component – Hot air and Induction

1 Principle of LS and SA sealing

LS strip Application

three steps:

1) Visual inspection of LS position and check of heat and

pressure distribution

2) Sealing quality check, by performing the mechanical

tear down of the LS Strip

3) ) LS Strip tightness, by performing the red ink injection p g y p g j

test

2 Cut two opposite corners

3 Empty the package content

4 Cut the sample corner to corner

2 Evaluation – Visual inspection

Preparation Sample

5 Open up the sample, rinse it with water and dry it

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2 Evaluation – Visual Inspection

Why Visual inspection

indication if there are any malfunctioning sealing

components in the machine

area and strip position

Note! Good light is important when

evaluating the seal quality

2 Evaluation – Visual inspection

Strip Position

The LS strip is not always centred with respect to the seal For MPM and MSE LS strip types, 60-70% of the strip covers the SA side or

~ 4.2 – 4.9 mm

G id li Th i (4)

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Guideline : The air gap (4)

should be simply visible and not exceeding 1.0 mm

2 Evaluation – Visual Inspection

Heat distribution by Zonoscope

2 Evaluation – Visual inspection

Scratches mark

Defective Defective

Defective Defective

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Check inside surfaces for scratches Inside deep scratches

might cause package integrity problem

If there are any defects, corrective actions should be taken

Deep scratches – Compromise package integrity

2 Evaluation – Visual Inspection

Overheated, Blistering and Bubbles

Defective – Compromise package tightness

Defective Compromise package tightness

Bubbles Blisters

Overheated

2 Evaluation – Visual Inspection

LS strip wrinkle / Fish bone

Defective–

Defective

Compromise package tightness

Wrinkle in strip, most likely due to strip position too much on LS side

Too high spring

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Too high spring pressure or temperature

of affecting the

of affecting the performance.

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2 Evaluation – Visual Inspection

The presence of blisters in the LS or SA side of the strip pindicates too high sealing

setting, either energy or

2 Evaluation – Visual Inspection

Defective

-Blocked seal

Defective Blocked seal

-Strip and inside

3 Evaluation – Tear down

Preparation Sample

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1.Unfold the flaps of package

sample

2 Cut two opposite corners

3 Empty the package content

4 Cut the sample corner to corner

2 Evaluation – Tear down

Preparation Sample

5 Open up the sample, rinse it 6 Cut the package sample along the

2 Evaluation – Tear down

Pull off the outer

Tear down evaluation – Check Overlap

Pull off the outer layer where it is double, overlap

Check that the overlap is properly sealed since is giving strength to the

Double layer not complete separate

strength to the final package

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Good overlap when the seal

is even and rupture at least

on outside PE layer

Double layer must be complete separate

2 Evaluation – Tear down

Tear down evaluation – Bad/uneven seal Overlap

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2 Evaluation – Tear down

Tear down evaluation – Good Overlap

Outer PE layer removed Outer PE and some

When the strip is pulled off and one of the inner coatingthe inner coating comes off with the strip (1) leaving a rupture edge (2) along the seal

3 Evaluation – Tear down

GOOD SEAL

Separation between the Al- foil and the inside coatings

When the strip (1) is pulled off and the two

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pinner coatings come off leaving the Al- foil uncovered

3 Evaluation – Tear down

GOOD SEAL

Rupture in the paperboard

When the strip is pulled outwards and all inner layers including the Al-foil

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including the Al-foil come off with the strip (1), leaving paperboard fibres(3)

3 Evaluation – Tear down

GOOD SEAL GOO S

Separation in the LS strip

When the strip(1)

is pulled off and one of the strip is left on the packaging

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packaging material This can happen also in the cross, where LS and TS meet

3 Evaluation – Tear down

GOOD SEAL

Separation of laminate PE

When all inner layers including the Al-foil come off with the strip (1) leaving part of the

3 Evaluation – Tear down

Defective seal Cold or

blocked seal

When the strip (1) is pulled off and it comes off leaving the inner coatings

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the inner coatings unaffected or with a grayish surface

4 Evaluation – Red Ink Injection

Preparation of the sample

1 Unfold the flaps of

package sample

3 Open the sample ,rinse it with water and dry it

4 Evaluation – Red Ink Injection

Preparation of the sample

Be careful not to over stress samples during their preparation

4 Evaluation – Red Ink Injection

►Inject 1 ml of red ink into

Procedure

►Inject 1 ml of red ink into the air channel of the LS with a 1 ml syringe

►The needle should be around  0.4-0.5 mm to get into the air channel

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4 Evaluation – Red Ink Injection

Check that the strip is

Evaluation of the samples – Critical area

Check that the strip is tight and no Transversal air channels are present

Critical points are where the LS and the TS meet, and on the top and and on the top and bottom creases

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4 Evaluation – Red Ink Injection

4 Evaluation – Red Ink Injection

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4 Evaluation – Red Ink Injection

in the air channel

d are worsened making a leaking channel.

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5 Defect Sample

Longitudinal Sealing