Presence, absence and counting inspection
Missing components, wrong orientation and incorrect counts in assemblies, packs, trays and kits.
Technical review: Frank GuoReviewed
A camera station can check that every component is present, the right way round and in the right place in an assembly, and that a pack, tray or kit holds the right number of items. It works when each item is visible from the camera and sits in a predictable place. Items hidden under others, stacked or heavily overlapping cannot be counted reliably from one view. We confirm this on your samples before proposing a station.
What a presence and counting station checks
Four checks, often combined in one image. Which you need is set at the sample test.
Missing components
Screws, clips, seals, inserts, leaflets or labels missing from an assembly or pack.
Orientation and wrong part
Parts fitted upside down, rotated or of the wrong variant, told apart by shape, colour or marking.
Count in pack, tray or kit
The number of items in a tray, blister, carton or kit compared with the count for the SKU.
Position and seating
Items in the right pocket or location; a part sitting proud can be seen from a side view.
How presentation decides feasibility
| Situation | Camera check | Conditions |
|---|---|---|
| Trays, blisters and pocketed kits | Usually feasible: each pocket is checked for its item. | Pockets visible; items contrast with the tray. |
| Assemblies on a fixture | Usually feasible: each location is checked for its part. | Parts visible from one or more fixed views. |
| Loose items in an open box | Often feasible in a single layer. | Touching items must be told apart by shape or spacing. |
| Stacked or overlapping items | Not reliable from one view. | Needs single-layer presentation, several views or another method such as weighing. |
| Closed or sealed packs | Not feasible with a camera. | Check before the pack is closed. |
Where presence and counting inspection stops
We agree these boundaries before a project starts, so nobody expects the camera to do what it cannot.
Not detectable with a camera
- Hidden items. Parts under other parts, behind covers or inside closed packs.
- Stacks and heavy overlap. Layers and items lying on top of each other cannot be counted from one view.
- Function. A part can be present and correctly placed but still not clipped, tightened or working.
Works reliably when
- Items have defined places. Pockets, fixtures or single-layer presentation.
- Items contrast with the background. Colour, shape or lighting separates each item from what is behind it.
- The trigger is timed right. The image is taken when every item is in place and still.
How a presence and counting station is laid out
Plan view of a typical station for trays. The real layout follows the site survey.
Swipe sideways to see the whole drawing →
What a pass and a reject look like
Illustrations, not images from a real line. The expected count and orientation for each SKU come from your pack specification.
Tray complete
Every pocket holds an item, all facing the same way. The count matches the SKU.
Item missing
One pocket is empty, so the count is short. The tray is tracked to the reject.
Item reversed
All items are present, but one is upside down, detected from its marking.
What we need to know about your line
These conditions decide the station design. Each is confirmed on site or during the sample test.
| Condition | What we need to know | Why it matters | Confirmed during |
|---|---|---|---|
| Pack or assembly format | Trays, kits, assemblies or cartons; how many variants. | Decides views, lighting and one recipe per variant. | Sample test |
| Check position | Where in the process the check can sit. | It must come after the last item is added and before the pack is closed. | Site survey |
| Trigger | Product sensor, machine-ready signal or indexing table. | The image must be taken when every item is in place and still. | Design review |
| Speed and spacing | Packs or assemblies per minute and the gap between them. | Sets exposure and trigger; each unit must be rejected on its own. | Site survey |
| Reject and confirmation | Reject mechanism or machine stop; PLC make and model. | Incomplete units must leave the line, or the machine must stop, with a sensor confirming it. | Design review |
How the station is accepted
False rejects and missed defects pull against each other. We define both, and how they are measured, before FAT and SAT.
False reject rate
The share of complete units rejected, measured on agreed good samples at line speed. The acceptable level is agreed per project.
Missed defect rate
The share of incomplete units that pass, measured with a missing, reversed or extra item at each position. The target is set with you.
Variant handling
A test that each SKU loads its own recipe and count, from the PLC or the operator screen.
What to prepare for the sample test
We check your packs or assemblies before proposing a station. We confirm quantities and shipping with you first.
Sample preparation guideComplete samples
Complete packs or assemblies for each variant, as they reach the check point.
Incomplete samples
Units with a missing, reversed, extra or partly seated item, clearly marked.
Pack specification
Bill of materials or pack list per SKU, with photos of a correct unit.
Line information
Speed, spacing, trigger options, PLC make and model, and the reject you have or need.
Presence and counting questions
How can missing components be detected during assembly?
How can items in a pack be counted automatically?
Can the station check a closed box?
Does the station confirm that a screw is tightened?
Request an assessment for this application
Tell us what should be in each pack or assembly and send complete and incomplete samples. We will tell you what a station can check.