Non-Destructive Inspection Technology for Retort Pouches
Tony Stauffer
Packaging Technologies & Inspection
Tuckahoe, New York
PTI Inspection Systems: www.ptiusa.com
800.532.1501
Pti@ptiusa.com

SealScan™
Only Seal Inspection system that is:
• Non-destructive
• Non-invasive
• Non-contact

Applications of SealScan™ 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

SealScan™
• 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

SealScan™ Principle of Through Transmission
Ultrasonic Signal
SEAL
Transmitter
Pouch seal or package material is placed between ultrasonic transmitter and receiver
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.

SealScan™ Technology
Ultrasonic 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.

SealScan™ 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
•
L-Scan produces a graph of the signal and summary data.
• C-Scan produces an
‘Opto-Acoustic’ image 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
3.5 mm
6 mm
10 mm
C-Scan window statistics
128 mm
135 mm
Modified L-Scan

C-Scan Analytical Tools
3.5 mm
16 mm
6 mm
10 mm
C-Scan statistics of moving window
135 mm

Optimizing the Sealing Process
Seal-
Scan™ serves as an analytical tool to determine optimal sealing conditions; e.g. temperature, dwell time, etc.
Maximum and Minimum Signal Values at Different Temperature
100.0
80.0
Variation decreases with increasing temperature.
Optimal Sealing
Temperature
60.0
40.0
-40.0
-60.0
-80.0
-100.0
20.0
0.0
100
-20.0
110 120 130 140 150 160 170 180
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.
190
Max
Min
Temperature at Which Pouch is Sealed

Material Analysis
HDPE exhibits better sealing uniformity and quality at higher temperatures.
105 C HDPE 105 C HDPE 105 C HDPE 105 C HDPE 105 C HDPE
TYVEK ® exhibited weaker bonding at higher temperatures.
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

SealScan™ and Peel Strength Testing
Background
• Pouches with peelable seals were tested.
• Peel strength test was performed on specific area of seal sample, approximately one-inch.
• SealScan™ C-Scan mode analysis of entire length of seal was performed.
• Results confirm direct correlation of both methods.

SealScan™ and Peel Strength Testing
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.
10
9
8
R
2
= 0.833
Avg Load
Maximum Load
Linear (Avg Load)
Linear (Maximum Load)
7
6
5
4
5 7 9 11 13
Ultrasonic Standard Deviation
15
R
2
= 0.7895
17 19

Good Seal Profile(Film-Pouch)
C-Scan
Seal width profile
Seal Quality Histogram
L-Scan
Seal Width Data, mm
Avg
8.2
Min
7.0
StD
0.7
L-Scan Statistics, % Signal Value
Avg
33.1
Min
27.7
Max
41.2
StD
1.9
Test results to be compared against Pass-Fail reference values.

Defective Seal Profile (Alu-Pouch Channel Leak)
C-Scan
Seal Quality Histogram
Seal width profile
L-Scan
Seal Width Data, mm
Avg
9.4
Min
3.5
StD
1.0
L-Scan Statistics, % Signal Value
Avg
1.7
Min
-80.5
Max
10.0
StD
8.0
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
3
Reject
Rate
.01% Leak
Corner channel
Wrinkle
Inclusion
Air bubbles
Waves
Blister
Fold
Total defects
Critical
Major or critical
Depends on height
Depends on height
Depends on size
Usually minor
Minor
Minor
12
86
11
4
19
4
8
147
.01%
.03%
.01%
.06%
.04%
.29%
.04%
.49%

Leak
Corner
Channel
Wrinkle
Case Study Heinz Douarnenex, Fr
Typical Defects
Critical
Critical
Critical
(may vary)
Minor
Inclusion
Critical

Air
Bubbles
Case Study Heinz Douarnenex, Fr
Typical Defects
Critical
Critical
Waves
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 SealScan™ Head

PTI-550 Online Pouch Inspection
Seal-Scan Head with Operator interface

PTI-550 Online Pouch Inspection

Packaging Technologies & Inspection
SealScan™ 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