Seal-Scan Inspection for Pouches 109

Seal-Scan™

Non-Destructive Inspection Technology

for Retort Pouches

Tony StaufferPackaging Technologies & Inspection

Tuckahoe, New York

PTI Inspection Systems: www.ptiusa.com800.532.1501

[email protected]

Seal-Scan™

Only Seal Inspection system that is:

• Non-destructive

• Non-invasive

• Non-contact

Applications of Seal-Scan™ Ultrasound Inspection

• Analyzes seal quality of pouches and flexible packages

• Characterizes bonded materials

• Works with all materials: film, alu, paper, or composite

• Process control

• Quality control

• Research and development

Seal-Scan™

• Produces a single linear scan in less than 1 second

• Digital pouch seal image in less than one minute

• Images and characterizes bonded materials

• Helps in process optimization

Seal-Scan™ Principle of Through Transmission

SEAL

Transmitter Receiver

Ultrasonic Signal

Pouch seal or package material is placed between ultrasonic transmitter and receiver

Ultrasonic Signal

• Ultrasonic waves propagate through single or multiple layers of well bonded materials.

• Transition through different mediums causes reflection of sound waves and reduces/eliminates signal strength.

Seal-Scan™ TechnologyUltrasonic signal is transmitted along the X-axis through seal and signal is recorded.

Signal measurement correlates to color gauge, creating high resolution image of seal structure and quality.

Seal-Scan™ Signal Scale Opto Acoustic Image

•The colored gauge represents the scan signal measurement.

•Pink is low signal, green is normal signal (good seal), purple is high signal.

•Total 6000 grades of color are used.

Scanning Modes

• C-Scan produces an

‘Opto-Acoustic’ image and summary data

• L-Scan produces a graph of the signal and summary data.

Pass – Fail Criteria and Data Integrity

Pass – Fail limits are set for

the average, minimum,

maximum, and standard

deviation of the signal

measurements,

All results are recorded

using the system’s data log.

Seal-Scan™ 525 Offline Analytical Equipment

C-Scan Analytical Tools

10 mm

135 mm128 mm

6 mm3.5 mm

C-Scan window statistics

Modified L-Scan

C-Scan Analytical Tools

C-Scan statistics of moving window

10 mm

135 mm16 mm

6 mm3.5 mm

Optimizing the Sealing Process

Maximum and Minimum Signal Values at Different Temperature

-100.0

-80.0

-60.0

-40.0

-20.0

0.0

20.0

40.0

60.0

80.0

100.0

100 110 120 130 140 150 160 170 180 190

Temperature at Which Pouch is Sealed

Sig

na

l V

alu

e

Max

Min

As the the temperature at which the seal is created increases, the maximum signal values are not affected. However, the minimum values experienced increase with higher temperatures, producing optimum seals at 160 and 180.

Variation decreases

with increasing

temperature.

Optimal Sealing

Temperature

Seal-Scan™ serves as an analytical tool to determine optimal sealing conditions; e.g. temperature, dwell time, etc.

105 C HDPE 105 C HDPE 105 C HDPE 105 C HDPE 105 C HDPE

128 C HDPE 128 C HDPE 128 C HDPE 128 C HDPE 128 C HDPE

108 C TYVEK 108 C TYVEK 108 C TYVEK 108 C TYVEK 108 C TYVEK

134 C TYVEK 134 C TYVEK 134 C TYVEK 134 C TYVEK 134 C TYVEK

Material Analysis

HDPE exhibits

better sealing

uniformity and

quality at higher

temperatures.

TYVEK®

exhibited

weaker bonding

at higher

temperatures.

Background

• Pouches with peelable seals were tested.

• Peel strength test was performed on specific area of seal sample, approximately one-inch.

• Seal-Scan™ C-Scan mode analysis of entire length of seal was performed.

• Results confirm direct correlation of both methods.

Seal-Scan™ and Peel Strength Testing

Seal-Scan™ and Peel Strength Testing

R2 = 0.7895

R2 = 0.833

4

5

6

7

8

9

10

5 7 9 11 13 15 17 19

Ultrasonic Standard Deviation

Pee

l S

tren

gth

Ave

rag

e L

oad

(N

)

Avg Load

Maximum Load

Linear (Avg Load)

Linear (Maximum Load)

The Standard Deviation of the ultrasound signal correlates to the peel

strength of a peelable seal. Seals with more variation in the quality of a

sealed area will be easier to peel than a seal area that is uniform. If a seal

has strong points of bonding but exhibits high variation, the peel strength

of the seal will be less.

Good Seal Profile(Film-Pouch)

C-Scan

Seal width profile

L-Scan

Seal Width Data, mm

L-Scan Statistics, % Signal Value

Avg

Min

StD

8.2 7.0 0.7

Avg MinMax StD33.

127.

741.

2 1.9

Seal Quality Histogram

Test results to be compared against Pass-Fail

reference values.

Defective Seal Profile (Alu-Pouch Channel Leak)

Avg

Min

StD

9.4 3.5 1.0

Avg Min Max StD

1.7

-80.

5 10.

0 8.0

C-Scan

Seal width profile

L-Scan

Seal Quality Histogram

Seal Width Data, mm

L-Scan Statistics, % Signal Value

Low average and minimum, with high

standard deviation.

Case Study Heinz Douarnenex, Fr

Defect Profile - 30,000 pouches were visually inspected 100%

Defect type Comment Number detected

Reject Rate

Leak Critical 3 .01%

Corner channel Major or critical 4 .01%

Wrinkle Depends on height 8 .03%

Inclusion Depends on height 4 .01%

Air bubbles Depends on size 19 .06%

Waves Usually minor 12 .04%

Blister Minor 86 .29%

Fold Minor 11 .04%

Total defects 147 .49%

Case Study Heinz Douarnenex, Fr

Typical Defects

Leak Critical

Corner Channel Critical

Wrinkle Critical (may vary)

Inclusion

Minor

Critical

Case Study Heinz Douarnenex, Fr

Typical Defects

Air Bubbles

Critical

Waves

Critical

Minor

Critical

PTI-550 Online Pouch Inspection

Pouches go onto Seal-Scan from pouch machine at 60-70/Minute

PTI-550 Online Pouch Inspection

1. Pouches are dropped into a special conveyor

2. Pass through PTI Seal-Scan Ultrasonic-head

3. Accepted or rejected

PTI-550 Online Pouch Inspection

Pouch Seal is guided through the Seal-Scan™ Head

PTI-550 Online Pouch Inspection

Seal-Scan Head with Operator interface

PTI-550 Online Pouch Inspection

Packaging Technologies & Inspection

Seal-Scan™ 525 Defect Gallery

Channel

Description• An area of non-bonding across the seal that will generally leak

Cause• Sealing bar settings were not correctly set (temperature, pressure and/or

dwell time.)

• Contaminants may be present during seal formation.

Compressed Seal

Description• Any separation of laminates in seal area. Material bond strength is

questionable in defect area. Visual evidence of overheating such as

bubbles.

Cause• Sealing bars were too hot during seal formation.

• Material bond strength is inadequate.

Contamination

Description• Foreign material is trapped in seal. Retort pouches will have noticeable

raised areas in seal where sealing bar sealed over contamination.

Cause• Seal area was contaminated during filling stage.

Crooked Seal

Description• A seal that is not parallel to the cut edge of the pouch

Cause• Pouch was misaligned in the sealing jaws.

Cut

Description• A breach of all layers of the laminate, where the hermetic integrity of the

package was compromised.

Cause• Equipment damage or “scrap” between laminate plies during formation.

• Pouch contacted sharp edges of other pouches or equipment.

• Pouches were abused during online or post-process handling.

Delamination

Description• Separation of laminated materials – can occur before or after retort

process. Delaminations ultimately affect seal strength through life

cycle/distribution process.

Cause• If occurring at the seal, bars were too hot during seal formation.

• If during retort process, residual air in the pouch was not controlled to

eliminate pouch expansion during retorting.

Incomplete Seal

Description

• Seal area does not extend completely across the width of

pouch.

Cause• Pouch was not positioned correctly in sealer and sealing bar.

Narrow Seal

Description• Container seal area has no margin of safety to accommodate seal creep

or wrinkles.

Cause• Defective sealing bars reduced seal width.

• Defects that cross seal, seal creep or mechanical separation reduce seal

width.

Non-Bonding Seal

Description• Sealing films fail to weld during sealing process. Defect appears as faint

sealing bar impression on retort seals. Application of slight pressure to

seal will cause failure.

Cause• Seal area was contaminated.

• Sealing bar settings were not correct (pressure/temperature/dwell time).

Wrinkle

Description• Material fold on one seal surface, caused when one seal surface is longer

than the other. Can also be a severe fold over both seal surfaces at

sealing time.

Cause• Sealing surfaces were not flat and parallel or were not tensioned.

• Various other irregularities in sealing bar or surfaces.

Pouch Inspection Economics

One technology useable for all materials

Non-Destructive, Non-Invasive

No sample preparation,

No special Inks, no added variable costs

Replaces costly, low efficiency manual Inspection

Reduces/eliminates Incubation

Saves product & packages

Long term quality tracking

Integrates into most pouch sealing machines

Real Time Process Control - allows immediate corrective action

Increases line efficiency

Good return on investment

You sleep better at night

Thank You