Machine vision inspection for agro-processing lines
Camera checks for grain milling, sugar, animal feed, fruit and nut packing and dried goods.
Technical review: Frank GuoReviewed
On agro-processing lines, camera checks usually confirm the bag label and date or batch code, check that a heat seal or stitch line looks complete, and look for foreign matter visible on the surface of product on a belt. Vision cannot see inside a bag or under the product, and a visible seal check is not a leak test. Dust, humidity, cleaning and vibration decide how the station is built.
Inspection points on a bagging and packing line
A typical sequence for milled products, sugar, feed, nuts or dried fruit; your line may differ.
Swipe sideways to see the whole drawing →
What goes wrong at each step
Visible faults by step, and the application that checks for them.
| Production step | Typical visible faults | Inspection |
|---|---|---|
| Cleaning and sorting | Stones, husks, sticks, plastic or string on top of the product | Surface defect detection (visible surface only) |
| Bag filling | Product in the seal area; bag top folded | Fill level, cap & seal |
| Sealing and stitching | Open, creased or contaminated seals; missing stitch lines | Fill level, cap & seal |
| Coding and labelling | Missing, smudged or wrong codes; the wrong bag print after a changeover | OCR/OCV & date codes Label & print inspection |
| Palletising | Missing bags in a layer | Presence, absence & counting |
Checks that apply on agro-processing lines
Label, code and seal checks can often share one station.
Label & print inspection
The right bag print or label for the product and pack size.
OCR/OCV & date codes
Dates and batch codes on paper, woven and film bags, checked against the run.
Visible seal & stitch
Heat seal visibly complete, stitch line present. Not a leak test.
Visible foreign matter
Objects that differ in colour or shape, on top of product on a belt.
Agro-processing inspection scenarios by product
Typical products from South African mills, sugar plants, feed mills and packhouses, 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 bags and product. Moisture, grade, net weight and anything inside a bag need other instruments.
| Product / line position | What is inspected | Typical fault caught | Inspection method | Related application |
|---|---|---|---|---|
| Maize meal bagsafter the filler and bag closer | The grade printed on the bag, such as super or special, and the date code | The wrong grade bag after a changeover; missing or smudged code | Camera over the bag face with diffuse light; OCV on the code | Label & print inspection |
| White and brown sugar packsafter the packer | Printed date and batch code; top seal | Missing code, open or creased top seal | Camera over the pack with light across the seal | OCR/OCV & code inspection |
| Cake and bread flour bagsafter dust extraction at the packer | Printed code on the bag face or gusset | Code hidden or smudged by flour dust, missing code | Camera in a purged housing with diffuse light | OCR/OCV & code inspection |
| Animal feed bagsat the sewing head | Stitch line across the top and the sewn-in label | Missing stitch, missing sewn-in label, unfolded bag top | Side camera just after the sewing head | Fill level, cap & seal |
| Seed maize bagsat bagging | Cultivar name and lot number on the bag or tag | The wrong cultivar print or tag, missing lot number | Camera over the bag face; OCR/OCV on the lot number | OCR/OCV & code inspection |
| Rice and dried bean pouchesafter the vertical form-fill-seal machine | End seals and the printed code | Grains trapped in the seal, missing code | Camera at the jaw exit with light across the seal | Fill level, cap & seal |
| Raisins and dried apricotson the inspection belt before packing | Visible stems, stones and foreign matter on a single layer | Cap stems, stones, twigs | Colour camera over the belt with diffuse light | Surface defect detection |
| Macadamia and pecan kernelson the belt before retail packing | Visible shell pieces and discoloured kernels | Shell fragments on the surface, dark kernels. Kernel-by-kernel ejection is a job for an optical sorter | Colour camera over a single layer | Surface defect detection |
| Rooibos tea cartonsafter the cartoner | Flaps closed; printed best-before and batch code | Open flap, missing or wrong code | Camera over the carton end with diffuse light | OCR/OCV & code inspection |
| Citrus export cartonsin the packhouse, before palletising | Carton label present and readable, with the packhouse and grower codes | Missing, unreadable or wrong carton label | Camera or code reader beside the conveyor | Carton & pallet verification |
| Egg traysafter the egg packer, before closing | Every cell filled | Empty cell. Cracked shells need a dedicated egg grader | Overhead camera with diffuse light | Presence & counting |
| Bulk bags (FIBCs)at the bulk bag filler | Label in the document pocket present and readable | Missing label, or the wrong one for the batch | Camera or code reader at the filling frame | Carton & pallet verification |
Optical sorting and fruit grading: sorting machine or inspection station?
Where a dedicated optical sorter or fruit grader belongs, and where an integrator-built station helps instead.
Bulk sorting is a machine you buy. An optical sorter feeds loose product, such as maize, beans, nuts or raisins, down a chute or along a belt in a thin layer. Cameras or sensors look at every piece, and a bar with many air valves, one beside the next across the width, blows individual rejects out of the stream. Fruit graders do the same for whole fruit on rollers or cups. These are purpose-built machines from sorter and grader manufacturers, bought with their own software and service. addaScan does not build bulk optical sorters, colour sorters or fruit graders.
An integrator-built station fits after the sorter. Once product is packed, the questions change: is the bag label right, is the date and batch code readable, is the seal or stitch line complete, is the carton marked for export, are all cells in the tray filled? Those are the checks on this page. Where units arrive one at a time, such as trays, cartons or single pieces on a conveyor, a station can also sort them into classes if the sample test shows the classes can be told apart reliably.
So if your problem is loose product quality, whether it calls for a fruit sorting machine, a fruit grading machine, grain sorting or nut sorting, talk to sorter and grader suppliers first. If it is packing, labelling, coding and dispatch, this is where an inspection station helps.
Packhouse export marking (PPECB)
For fresh produce exports, the PPECB carries out end-point export inspection covering quality, phytosanitary aspects and marking requirements, and approved product is stamped as passed for export. A camera or code reader beside the carton conveyor can confirm, before palletising, that each carton carries a readable label with the codes expected for the run. It does not judge fruit quality inside the carton, and it does not replace the PPECB inspection.
Before specifying a packhouse check, use the PPECB export carton marking guide to map PUC, packhouse and run data to the printed carton and define how mismatches are held for correction.
Source: PPECB product inspection services (read 2026-09-25).
Conditions specific to mills, sugar plants and packhouses
These decide whether a station keeps working through a season.
Flour, sugar and feed dust
Dust dims lenses and lights. Sealed housings and filtered air across the window help.
Moisture and condensation
Cold rooms, steam and humid packhouses fog windows. Housing and position allow for this.
Washdown or dry cleaning
Packhouses are often washed down; mills are usually cleaned dry. Housings and cable glands suit your method.
Hot days and cold mornings
Unconditioned sheds swing between heat and cold. Electronics are rated for the range.
Mills, sifters and baggers
Vibration blurs images and loosens focus. Cameras mount on rigid stands with focus locked.
What vision does not do on an agro-processing line
We agree these boundaries before a project starts.
Needs another method
- Foreign bodies inside a bag or under the product. These need metal detection or X-ray inspection.
- Seal integrity. A seal or stitch can look right and still leak. Leak testing is a separate method.
- Net content. Declared quantity needs a checkweigher.
- Product quality. Moisture, grade and hidden insect damage need sampling or other instruments.
Works reliably when
- Bags arrive flat and consistent. A guide or flattener presents print and seal the same way.
- Optics are protected and cleaned. Cleaning is part of the routine.
- Recipes follow the product. Each print and pack size has a recipe, selected at changeover.
What to send for a sample test
We test your own bags and product before proposing a station. The same samples later define acceptance.
Sample preparation guideGood bags
Sealed bags from normal production, for each pack size and print.
Defect samples
Missing or smudged codes, wrong prints and poor seals, each marked.
Foreign matter
Examples of what must be caught, next to normal product.
Acceptance
False rejects and missed defects at line speed; levels agreed per project.
Why manual inspection struggles on these lines
Conditions on mills, sugar plants and packhouses that make checking by eye unreliable over a full shift.
- Dust. Flour, sugar and feed dust settles on bags and in the air, covering codes and print and tiring the eyes.
- Speed at the bagger. Bags follow each other quickly, so seals, stitch lines and codes get a glance at best.
- Natural variation. Grain, fruit and other produce vary in colour and shape, which makes small foreign matter on a moving belt hard to spot.
- Heat, cold and humidity. Unconditioned sheds, cold rooms and steam make long periods of close inspection uncomfortable.
- Long shifts in season. Peak season brings long shifts and many prints and pack sizes, which is when attention runs lowest.
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 for agro-processing
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) |
|---|---|---|---|
| Fruit carton marking inspection | Missing, faint, skewed or wrong carton marking; unreadable carton barcode | Code reader + camera at the carton end, carton pusher | R 210 000 – R 940 000 |
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.
Keep optical grading, export marking and food safety distinct
Hortgro represents South African deciduous-fruit interests. PPECB’s Product Inspection Services describes export inspections covering quality, phytosanitary aspects and marking requirements. (Hortgro: South African deciduous fruit industry organisation) (PPECB: Product Inspection Services) This is a useful boundary for a packhouse project: a camera can contribute evidence about a visible fruit surface or a carton label, but it does not replace commodity-specific export inspection, phytosanitary certification or food-safety controls.
| Packhouse or processing step | Optical task | Failure and consequence |
|---|---|---|
| After cleaning and presentation | Visible external blemish or foreign item under the chosen views | Wrong grade or visible contamination proceeds downstream |
| Grading and portioning | Appearance class, size where calibrated, presence in a tray | Uneven pack presentation or avoidable downgrading |
| Carton closing | Correct commodity, variety and controlled marking data | Correct produce is associated with the wrong carton identity |
| Pallet assembly | Carton-to-pallet identity and destination consistency | Traceability mismatch may require holding and rebuilding the load |
Natural variation needs an agreed reference set: maturity, colour and harmless surface variation can overlap with defects. Capture acceptable seasonal variation as well as obvious failures. Where colour is a quality signal, fix illumination and exposure and validate after window cleaning. Otherwise a maintenance action can move an appearance threshold even though the product has not changed.
In a hypothetical export run, the printed variety matches the visible artwork but the controlled order specifies another variety. The camera should compare a readable field with the authorised order, then hold the carton when they disagree. It cannot decide which source is correct. The packhouse quality owner resolves the product identity and controls any relabelling; a fresh image alone is not permission to release a held consignment.
R638 provides South African food-premises hygiene context for installation, cleaning and product handling. (South Africa: food premises and transport hygiene regulations R638, 2018) Use cleanable guards and a documented lens-window check without allowing a maintenance brush or loose fixture to become a foreign-body source. Test changes in moisture and product presentation that occur through the shift. The financial consequences include downgraded saleable product, manual sorting, repacking and shipment delay; quantify them from the packhouse records, without assuming an inspection station eliminates all of them.
Agro-processing inspection questions
Can a camera check the print and batch code on maize meal or sugar bags?
Can vision confirm that a bag or pouch is properly sealed?
Can machine vision detect foreign material in grain, nuts or dried fruit?
How do cameras cope with flour, sugar and feed dust?
What is an optical sorter?
Is an optical sorter the same as an inspection station?
Can a camera check the labels on citrus or fruit export cartons?
Sources
- Hortgro: South African deciduous fruit industry organisation (local industry context; read 2026-10-27)
- PPECB: Product Inspection Services (export inspection includes quality, phytosanitary and marking requirements; read 2026-10-27)
- South Africa: food premises and transport hygiene regulations R638, 2018 (hygiene framework; no camera certification claim; read 2026-10-27)
Request an assessment for your line
Tell us the products, bag types, faults and conditions around the line. We will say which checks apply and what a sample test needs.