How do you keep metal out of milk, yoghurt and cheese packs without constant false rejects? Choose the right platform for the product, teach each SKU to cancel product effect, right-size the aperture, protect your CCP with hygienic rejects and data capture, and validate sensitivity with real test pieces.
Why dairy detection is different
Dairy is wet and salty, which makes it conductive and easy to confuse with metal. Temperature swings between warm fill and chilled storage, plus formats such as tubs with foil lids, pouches, and films, add to the challenge. If the setup is off, sensitivity falls, and false rejects climb.
Pick the right platform
For industrial metal detection, Use conveyor detectors for sealed packs such as yoghurts, blocks, sliced cheese and butter. Use a pipeline for liquids and viscous products, placing the head close to the filler to reduce rework. Specify ferrous-in-foil when aluminium lidding is non-negotiable. If you need to see through foil or find more than metal, an X-ray is the alternative.
Sensitivity that actually works
Size the aperture to the largest pack, since smaller apertures yield higher sensitivity. Use multi-frequency and product learning, and teach each SKU at running temperature. Control orientation so packs pass consistently through the centre. Prove performance with ferrous, non-ferrous, and stainless steel spheres, typically 316, to your site or customer standard. Balance throughput against tiny sphere sizes to keep the line stable.
Hygienic design and CCP control
Pick stainless construction with open profiles and sloped surfaces. Where caustic washdown is standard, specify high IP options. Fit cleanable, lockable reject bins with sensor-confirmed ejection, full-bin alarms and air-failure defaults to reject. Lock menus, use role-based access and capture time-stamped events and batch IDs, with links to QA or OEE if required. Combo systems with a checkweigher can save space and strengthen due diligence.
Validation and routine checks
Run start-up, hourly, and changeover tests with certified components and record the pass/fail results. Validate at both warm and chilled states where needed. Challenge the reject system to prove the right packs land in the locked bin and cannot be retrieved. Schedule periodic independent verification against your code of practice. Train operators and engineers, and keep spares and PPM in place.
Dairy metal detection checklist
- Product matrix confirmed, including fat, salt and temperature
- Platform selected: conveyor, pipeline, ferrous-in-foil or X-ray
- Aperture sized to the tallest pack, orientation guides included
- Sensitivity targets agreed for Fe, NFe and SS, mapped to customer requirements
- Hygienic design confirmed, IP rating, open profiles, and cleanable reject
- CCP controls in place, sensors, alarms, bin locks, safe defaults
- Data capture and permissions set, with OEE or QA integration if needed
- Validation plan agreed, start-up, hourly and changeover checks with records
- Training and PPM schedule agreed, spares held
FAQs
- Why do we see so many false rejects on yoghurt?
Usually, the product is affected by changes in conductivity and temperature. Re-teach at running temperature, use multi-frequency and stabilise pack orientation. - Can detectors work with foil-lidded pots?
Yes. Use ferrous-in-foil technology, or choose X-ray if you need stainless sensitivity or wider contaminant coverage. - What sensitivity should we aim for in dairy?
It depends on pack size and aperture. Set realistic Fe, NFe and SS targets per SKU and verify against your code of practice, not brochure figures. - How often should we test the CCP?
At start-up, hourly as typical, at changeovers and end-of-run, plus after any intervention. Record results and investigate any fails immediately. - Should we combine the detector with a checkweigher?
Often yes. A combo saves space, reduces interfaces and strengthens due diligence with integrated rejection and unified reporting.
Call to action
Ready to stabilise your dairy CCP and cut waste? Talk to FESS Group via our contact page: https://fessgroup.co.uk/contact-us/
