A metal detector only protects food if someone proves it's working, and the log is that proof. Each check passes test pieces through the detector, often one ferrous, one non-ferrous and one stainless steel, each sealed in a test pack, and each has to be detected and pushed into the locked reject bin. The log records the time, the reason for the check, the product and lot, whether the detector was on that product's setting, each test piece and the reject arm, and who did it. Checks go at the start of the shift, at a set interval, at every product change, after any repair or failed check, and at the end. A failed check is the line that matters: everything made since the last passing check is held and run through again on a working detector, and the fix is written down. For a facility under FDA's preventive controls rule, the metal detector is a preventive control: these records are reviewed within 7 working days, and the corrective action steps are in the rule. A separate reject log records what each rejected pack turned out to hold. In the example below, a Colorado snack bar maker logs a Thursday with one failed check.
The short version
- Each check: three test pieces, each detected and rejected into the locked bin.
- Record time, reason, product, lot, setting, each test piece, the reject arm and initials.
- Check at the start, at a set interval, at every product change, after a fail or repair, and at the end.
- A fail holds everything since the last passing check, until it's run through again.
- Write down the cause and the fix; review the records within 7 working days.
- Log every reject, and what it turned out to hold.
- TaroStack keeps each run as a batch with its lot, so a hold finds every case. More below.
What a check records
| Field | Why |
|---|---|
| Date, time, reason | Shows checks happened when the plan says |
| Product, lot, setting | A detector set for another product can miss metal |
| Ferrous, non-ferrous, stainless | Each metal is detected differently |
| Reject arm and locked bin | Detecting isn't enough; the pack has to leave the line |
| Result, hold since | A fail points to the product to hold |
| Corrective action, review | What was done, and who checked the record |
The wider program, every way metal and other objects get in, is in foreign material control program, and how instruments are checked in scale calibration log.
The rules
| Rule | Where |
|---|---|
| Monitoring | Written procedures and frequency; monitoring documented in records (21 CFR 117.145) |
| Corrective action | Find and fix the problem, reduce the chance it recurs, evaluate the affected food, and keep it out of commerce if it can't be cleared (21 CFR 117.150(a)) |
| Verification | Checking instruments for accuracy; monitoring and corrective action records reviewed within 7 working days (21 CFR 117.165(a)) |
| Small businesses | Qualified facilities are exempt from the preventive controls, under modified requirements (21 CFR 117.5(a)) |
| Size that matters | Objects of 7 to 25 mm in ready-to-eat food are grounds for FDA action; under 7 mm rarely injures, except special risk groups (CPG Sec. 555.425) |
This is general information, not legal advice.
An example: a Thursday on the bar line
Ridgeline Bar Co., the made-up snack bar maker in Boulder, Colorado, I use in these examples, sells past $1 million a year, so FDA's preventive controls rule applies in full, and its food safety plan names a metal detector after the wrapper, against bits of the cutting blades and seed sieves. Its plan sets 2.0 mm ferrous, 2.5 mm non-ferrous and 3.0 mm stainless test pieces, checked every two hours. On Thursday, October 15:
| Time | Reason | Product | Setting right? | Result |
|---|---|---|---|---|
| 6:00 | Start of shift | Oat and honey | Yes | All pass |
| 8:00 | Every 2 hours | Oat and honey | Yes | All pass |
| 10:00 | Every 2 hours | Flax and chia | No | Stainless missed: hold since 8:00 |
| 10:20 | After a fail | Flax and chia | Yes | All pass |
| 12:00 | Every 2 hours | Flax and chia | Yes | All pass |
| 1:30 | Product change | Bran and date | Yes | All pass |
| 2:30 | End of shift | Bran and date | Yes | All pass |
The line had switched to flax and chia at 9:40 without switching the detector's setting, and nobody ran a check at the change. The 10:00 check caught it: the stainless piece went through. Everything since the 8:00 pass, about 2,000 bars, was held and run through again after the fix, with no rejects, and product changes now get their own check. At 12:40 the detector threw out a flax bar with a 3 mm piece of wire, traced to a broken seed sieve, which was replaced. The preventive controls lead reviewed the log on Monday, two working days later. The bars themselves are in high fiber claim.
Get the workbook
Download the metal detector log. Two sheets. Check log: each check's reason, product, lot, setting, test pieces and reject arm; the result, the time to hold product from and the working days to review fill in. Rejects: each rejected pack, what was found, its size and the action; whether it's in FDA's 7 to 25 mm range fills in. It's an ordinary Excel file with no macros, and it works in Google Sheets, LibreOffice and Numbers.
Where this stops working
"Hold everything since 8:00" is easy on the line and hard in the warehouse. By 10:30 some of those cases were stacked with the 6:00 cases, and only lot numbers tied to times sort them out.
How TaroStack does it
TaroStack keeps each run as a batch with its lot, so a hold finds every case.
Batches by lot. Each run is a batch with its own lot, its ingredient lots and how many cases it made.
Holds. A lot can be put on hold, so its cases can't go out until it's released.
Recalls. If held bars went out anyway, one report shows every customer who got them.
| The job | Notebook | In TaroStack |
|---|---|---|
| Which cases came from the held run | Pallet tags | Batches by lot |
| Keeping held cases from shipping | A sign on the pallet | A hold on the lot |
| Who got a bad lot | Invoices | One recall report |
Batches, holds and recalls are on every plan, from $49 a month. The first 30 days are free, with no credit card. If you'd like a hand setting up, ask, and we'll do it with you.