Scorch and texture inspection on socket faces
Socket-face appearance inspection should distinguish confirmed scorch from unfamiliar but acceptable texture. Record labels independently of model score.
Industry // Plastics & packaging
Request an assessmentPackaging inspection systems for plastics and packaging lines
Camera checks for injection moulded, compression moulded and thermoformed parts, closures, preforms and printed packaging, as part of packaging line automation.
Technical review: Frank GuoReviewed
// Short answer
A packaging inspection system is a camera station that checks moulded, thermoformed and printed packaging for visible faults: short shots, flash, specks and other surface contamination, print defects, key dimensions, orientation, and missing liners or tamper bands on closures. Results depend on how parts are presented, on normal cavity-to-cavity variation, and on lighting that suits clear or translucent material. Internal voids, moulded-in stress and material properties are not visible, so each check is confirmed on your own parts first.
// Where it fits
Inspection points from mould to pack
A typical sequence for moulded or thermoformed packaging; many lines skip printing or assembly.
[Schematic]Process flow · not to scale
Swipe sideways to see the whole drawing →
[1] Shape: short shots, flash, specks and forming faults at the machine exit.
[2] Dimensions: key features and orientation after take-out.
[3] Print: presence, completeness and registration after decoration.
[4] Liner & band: liner, wad, insert or tamper band present.
[5] Count: the right number of parts per bag or box.
// Defect risks
What goes wrong at each step
Visible faults by step, and the application that checks for them.
| Production step | Typical visible faults | Inspection |
|---|---|---|
| Injection moulding | Short shots, flash at parting lines and gates, black specks, burns, colour streaks | Surface defect detection |
| Thermoforming | Incomplete forming, webbing, torn or badly trimmed edges | Surface defect detection |
| Take-out and conveying | Key features out of size; parts on their side or upside down; double or stuck parts | Dimensional measurement Presence & counting |
| Printing and decoration | Missing, smeared or misregistered print; wrong artwork for the job | Label & print inspection |
| Closure assembly | Missing liner or wad, uncut or missing tamper band, missing insert | Presence & counting |
// Inspections
Checks that apply to plastics and packaging
Surface and dimension checks often share one camera when the part is held still at a known position.
Surface defect detection
Short shots, flash, specks, burns and forming faults, with lighting chosen for the material.
At: mould or former exit
Dimensional measurement
Diameters, heights and hole positions on selected features, without contact.
At: take-out or conveyor
Label & print inspection
Print presence, completeness and registration on cups, tubs, lids and closures.
At: after printing
Presence & counting
Liners, tamper bands and inserts present; parts the right way up; counts per bag or box.
At: assembly and packing
// Application map
Plastics and packaging inspection scenarios by product
Typical parts from South African moulders, converters and packaging plants, what a camera checks on each, and the application page with the detail. The method in each row is a starting point, confirmed on your own parts. Functional tests such as tamper band pull-off, leak testing and wall thickness stay separate.
| Product / line position | What is inspected | Typical fault caught | Inspection method | Related application |
|---|---|---|---|---|
| Water and soft-drink caps with tamper bandsat the moulding or slitting machine exit | Tamper band, bridges and the cap skirt | Uncut or broken bridges, a folded or short-shot band, flash | Camera looking into the cap with a ring light, plus a side view of the band | Surface defect detection |
| Lined and wadded closuresafter the lining machine | Liner or wad present, centred and flat | Missing, double or off-centre liner | Camera looking into the closure with diffuse light | Presence & counting |
| PET preformsat take-out or before the blow moulder | Neck finish, body and gate | Short or damaged neck finish, black specks, gate stringing, white haze | Backlight through the body; a finish camera looking down | Empty containers & preforms |
| Flip-top dispensing capsafter assembly | Lid closed and hinge intact; orifice insert present | Open or half-closed lid, missing insert | Camera looking down on the cap, low-angle light | Presence & counting |
| Thermoformed meat and fruit traysafter trimming and stacking | Formed shape and trimmed edge | Webbing, incomplete forming, torn or ragged trim | Backlight under clear trays; low-angle light on opaque ones | Surface defect detection |
| Injection-moulded bread and beverage cratesat the mould exit | Full outline, ribs, handle openings and the moulded logo | Short shot on a rib, flash in openings, burn marks | Wide-view camera or several cameras with diffuse front light | Surface defect detection |
| Paint pails with in-mould labelsafter the moulding cell | Label position and wrinkles; handle fitted | Shifted or creased label, missing handle | Side cameras around the pail, diffuse light | Label & print inspection |
| Blow-moulded HDPE bottles and jerry cansafter deflashing | Neck and handle area, bottle outline | Flash left at the neck or handle, an oval neck. Leak testing stays a separate station | Backlit profile; top camera on the neck | Dimensional measurement |
| Printed laminate toothpaste tubesafter printing and capping | Print registration and colour; cap fitted | Misregistered or missing colour, missing cap | Tube rotated past a camera, or several views, diffuse light | Label & print inspection |
| Dry-offset printed margarine tubsafter the cup printer | Complete print and text on the tub wall | Missing colour, smears, partial print | Camera with diffuse light as the tub turns, or several cameras | Label & print inspection |
| Blown filmon the winder | Film across its full width | Gels, holes, streaks and contamination | Line-scan camera over a backlight, paced by an encoder | Web & line-scan inspection |
| Self-adhesive label reelson the converter before rewinding | Printed labels on the moving web | Missing or smeared print, matrix not stripped, splices | Line-scan or strobed area camera across the web | Web & line-scan inspection |
| Woven polypropylene sacksafter cutting and printing | Printed panel, cut edge and stitched bottom | Misprint, frayed cut, missing stitch line | Camera over the flat sack with diffuse light | Surface defect detection |
For caps with incomplete rims or tamper-band bridges, the short-shot inspection guide for moulded closures explains defect visibility, sample coverage across cavities and the limits of a surface image before a station is selected.
// Integration
Conditions specific to moulding and packaging
These conditions decide how the station is taught and lit.
Cavities
Cavity-to-cavity variation
Parts from a multi-cavity tool differ slightly. Limits are taught from every cavity so normal variation passes.
We askGood parts from each cavity
Clear parts
Clear and translucent material
Front light passes through clear plastic; a backlight shows edges, short shots and flash that front light misses.
We askMaterial, colour and clarity
Appearance
Texture, gloss and colour
Textured or glossy surfaces and colour shifts between batches can look like defects. Normal appearance is taught from several batches.
We askSamples from several batches
Presentation
Orientation off the machine
Parts dropped from a mould land at random angles. A one-sided check needs consistent presentation or more views.
We askHow parts leave the machine
Changes
Mould and colour changes
A new tool, insert or colour means a new recipe or adjusted limits, selected with the job change.
We askTools and colours on the machine
Environment
Heat, static and dust
Warm parts may still be shrinking, and static pulls dust onto surfaces where it can look like contamination.
We askWhere parts are measured today
// Converters
Print control for converters supplying food plants (FSSC 22000 2.5.2(d))
What food customers ask packaging converters to prove, and where inspection fits.
Converters that print film, labels, sleeves or cartons for food plants certified to FSSC 22000 are asked to prove print control. Version 6 of the scheme (Part 2, 2.5.2(d)) asks packaging manufacturers for approval of each print run against the agreed standard or master sample, a process to detect and identify printing errors during the run, and segregation of different print variants.
In-run print inspection on the press or rewinder is covered on the web and line-scan inspection page. For moulded and decorated packs, a label and print check after decoration does the same job at part level. Artwork approval stays with pre-press and the customer.
Manual checks at the press or the moulding machine depend on each inspector’s judgement and attention, which vary across shifts, and skilled inspectors are hard to find and keep. A station applies the same limits to every part and keeps images for the quality team; it does not replace the setter who fixes the cause.
Source: FSSC 22000 Scheme Version 6, Part 2, 2.5.2(d) (read 2026-09-25).
// Limits
What a camera cannot tell you about a plastic part
We agree these boundaries before a project starts.
Needs another method
- Internal voids and stress. Voids inside opaque parts, moulded-in stress and material properties are not visible.
- Wall thickness of opaque parts. A camera sees the outline and surface, not the thickness of an opaque wall.
- Function and fit. Whether a closure seals or a clip snaps is a functional test; vision checks the visible features.
- Tight tolerances on large parts. Resolution is shared across the field of view; these may need several cameras, telecentric optics or another gauge.
Works reliably when
- Parts are presented consistently. A nest, guide or robot place gives each part the same position.
- Normal variation is sampled. Good parts from every cavity, batch and colour.
- Lighting suits the material. Backlight for clear parts, low-angle light for surface relief.
// Samples & acceptance
What to send for a sample test
We test your own parts before proposing a station; quantities and shipping are agreed first. The same samples later define acceptance.
Sample preparation guideGood parts
Parts from every cavity, and from different batches and colours if they vary.
Defect parts
Short shots, flash, contamination, print and assembly faults, including borderline ones, each marked.
Drawings
Part drawings with the dimensions and tolerances that matter to you.
Acceptance
False rejects on good parts from all cavities and missed defects on marked samples; levels agreed per project.
// Manual inspection
Why manual inspection struggles on these lines
Conditions on moulding and packaging lines that make checking by eye unreliable over a full shift.
- Continuous output. Machines eject parts every cycle, around the clock, so an operator checks samples and faults between samples go into the box.
- Clear and translucent parts. Short shots, flash and specks in clear material are hard to see under room lighting.
- Glare and gloss. Glossy surfaces and printed film reflect, and small print faults on a running web are hard to follow by eye.
- Heat and static. Warm parts are uncomfortable to handle and may still be changing shape; static pulls dust onto surfaces where it looks like contamination.
- Many cavities and colours. Knowing what is normal for every cavity, colour and tool is a lot to hold in mind on a busy shift.
These are reasons to automate the checks that are defined and visible, and to keep people for judgement and for fixing causes. The guide to manual or automated camera inspection compares the two.
// Line solutions
Line solutions for plastics and packaging
Complete stations for lines in this industry, each with the HIKROBOT hardware, installation and an indicative installed budget for a typical application in rand, excluding VAT. All line solutions →
| Line solution | Faults it catches | HIKROBOT configuration | Indicative budget (excl. VAT) |
|---|---|---|---|
| Closure inspection | Short shots, flash, broken tamper band bridges, missing or off-centre liners | Two to four views, backlight and dome light, air-jet reject | R 370 000 – R 1 290 000 |
| Folder gluer inspection | Glue missing on the flap (where visible), wrong print, unreadable barcode | Vision sensors or 4K line scan, UV light, machine kicker | R 170 000 – R 970 000 |
Basis of the budget column: an indicative installed budget for a typical application, in rand excluding VAT, as at 2 October 2026, the price date used on the line-solution pages. Projects involve custom requirements, so the firm price follows the sample test. Each row links to the line-solution page that shows the cost breakdown.
Connect moulding, converting and release checks
Plastics SA provides local industry representation, technical training and skills development. A South African packaging project can therefore be scoped around the actual conversion process and operator skills rather than a generic “AI quality” purchase. (Plastics SA: industry representation and skills development) Injection-moulded closures, blown bottles and printed flexible webs need different images, product handling and acceptance references even when they share a downstream filling customer.
| Process step | Image task | Typical consequence if missed |
|---|---|---|
| Mould ejection and presentation | Incomplete rim, flash, missing bridge and wrong orientation | Closure may fail assembly or damage a downstream capping operation |
| Bottle transfer before filling | Visible finish and wall defects, wrong container | Filling and labelling add value to a package already unsuitable |
| Printing and slitting | Registration, missing print and recurring defects by lane | A roll can carry repeated waste to the customer |
| Assembly and dispatch | Liner presence, component count and correct carton label | Wrong material or incomplete components enter the next line |
Do not combine all dark regions into a contamination class. A pigment swirl, a permitted recycled-material inclusion, a shadow under a rib and a missing section of plastic have different meanings. Make quality-approved reference groups for each resin, colour, cavity and finish in scope. If the cavity identifier is visible, retain it with the defect record so the process team can distinguish a recurring cavity fault from a handling fault shared by all parts.
In a hypothetical closure trial, compare a complete rim with a short-shot rim in a silhouette view, then inspect the liner from the open side. Passing the silhouette check alone does not release the liner requirement. HIKROBOT describes tools for locating, measuring and defect detection, but their existence does not establish coverage on this closure geometry. (HIKROBOT VisionMaster product page)
For learning-based classification, separate physical parts and production lots between development and validation. Rephotographing the same closure many times does not create independent defect variety. (Google Machine Learning Crash Course: dividing datasets) Evaluate translucent colours under the planned illumination and record accepted variation before choosing a threshold. When packaging is destined for food premises, R638 is relevant to the hygiene context of installation and handling; a camera decision does not establish food-contact material compliance. (South Africa: food premises and transport hygiene regulations R638, 2018) Record the consequences in useful categories: lost moulding yield, wasted print roll, line interruption, sort labour and customer returns. Use observed plant values when estimating savings.
// FAQ
Plastics and packaging inspection questions
What does injection moulding quality inspection check?
On the line, injection moulding (molding) quality inspection checks what is visible on each part: short shots, flash, sink marks, black specks, burn marks and colour deviation, key dimensions and orientation, and missing liners or inserts. Internal voids, moulded-in stress and material properties need other tests.
Can short shots and flash be detected on moulded parts?
Often, when the part is presented consistently. A backlight shows the outline of a short shot; low-angle light shows flash on a parting line. Thin flash on clear material is harder, so we test your parts first.
Will cavity-to-cavity variation cause false rejects?
It can if limits are taught from one cavity only. We teach limits from good parts from every cavity and review borderline parts with your quality team, so normal variation passes.
Can parts be measured straight off the machine?
The visible outline and features can be measured, but warm parts may still be shrinking. How camera results compare with your later lab measurements is agreed during the sample test.
What happens when we change moulds or colours?
Each tool or colour gets its own recipe or limits, selected with the job change so parts are not checked against the wrong reference. A new part needs samples and a teaching step.
Can vision inspect tamper bands on plastic caps?
Yes, for visible faults: uncut or broken bridges, a missing, folded or short-shot band, and flash. The camera usually looks into the cap and at the band from the side. Whether the band breaks correctly when the cap is opened is a functional pull-off test, which a camera cannot replace.
What does preform inspection check?
Visible faults in PET preforms: a short or damaged neck finish, black specks, gate stringing and white haze, usually at the machine take-out or before the blow moulder. Wall-thickness distribution, material properties and moulded-in stress need other methods.
Sources
- Plastics SA: industry representation and skills development (South African plastics industry context; read 2026-10-27)
- HIKROBOT VisionMaster product page (vendor tool description; previously checked 2026-09-25)
- Google Machine Learning Crash Course: dividing datasets (training, validation and independent test sets; read 2026-10-27)
- South Africa: food premises and transport hygiene regulations R638, 2018 (hygiene framework; no camera certification claim; read 2026-10-27)
// Plastics & packaging
Request an assessment for your parts
Tell us the parts, materials and faults you need to catch. We will say which checks apply and what a sample test needs.