SOP for Metal Detector and Deduster Operation and Cleaning

In short: This example SOP describes how production staff clean, set up, challenge and operate an in-line metal detector and a combo metal detector cum deduster on tablets and capsules. It is an illustrative template: adapt every limit, frequency and model-specific step to your own equipment manual and quality system.

1.0 Objective

To describe the cleaning, set-up, performance checking and operation of a metal detector and a digital combo metal detector cum deduster used for tablets and capsules.

2.0 Scope

This example SOP covers a metal detector (example model: Metaltrap 03) and a digital combo metal detector cum deduster (example model: Metaltrap SS30) used in an oral solid dosage plant. Replace the models with the ones installed at your site.

3.0 Responsibility

• Production officers and operators: clean and operate the equipment, run the challenge tests and complete the equipment logbook.
• Head of Production: review the SOP and ensure it is followed.
• Quality Assurance: ensure compliance, verify cleaning and approve line clearance before reassembly or use.

4.0 Abbreviations

5.0 Definitions

• Validation (machine check): passing the three standard test pieces (FE, NFE, SS) through the detector one after another, with an interval between them (example in-house criterion: 30 seconds).
• System check: a manual check that the test head is healthy (coil output within the range given in the equipment manual).
• Autolearn: passing good product continuously so the machine sets its own parameters (RPH, THR, PLT).
• Discretization: a setting in the equipment software that relates the signal to a percentage of the threshold.

6.0 Procedure

6.1 Cleaning, model Metaltrap 03

1. Switch off the main switch and remove the plug.
2. Replace the status label with a “To be cleaned” label.
3. Remove the plastic rotary chute and outlet chute and take them to the washing area.
4. Remove the “To be cleaned” label. Wash the parts with 2% approved non-ionic detergent solution (example in-house criterion) using a nylon scrubber.
5. Rinse with potable water to remove the detergent, then rinse twice with purified water.
6. Dry the parts with compressed air (filtered, oil-free). Wipe the machine with a moist lint-free duster followed by a dry one.
7. Refit the chutes and affix the “CLEANED” label.

6.2 Cleaning, model Metaltrap SS30

1. Switch off the main switch and remove the plug.
2. Replace the status label with a “To be cleaned” label.
3. Remove loose powder with a nylon brush and a lint-free cloth.
4. Remove the SS cover, SS spiral, inlet chute and outlet discharge chute of the deduster and take them to the washing area.
5. Remove the “To be cleaned” label. Wipe the outside of the machine with a wet lint-free duster until visually clean, then wipe with purified water.
6. Clean the inlet acrylic hopper, discharge chute, outlet acrylic hopper and acrylic rejection bottle with a wet lint-free duster. Wipe electrical cables with a dry lint-free cloth only.
7. Dry washed parts with compressed air or a dry lint-free cloth.
8. Production confirms that the equipment and area are free from powder and remnants of the previous batch, as per the area and equipment cleaning SOPs.
9. Reassemble only after QA has verified the cleaning.
10. Sign the equipment clean tag and record the cleaning in the equipment logbook.

Cleaning validity (example in-house criterion): cleaned equipment is valid for 48 hours. If it is not used within 48 hours, clean it again before use.

6.3 Checks and precautions

• Operators wear gloves and a nose mask during operation.
• Keep metallic objects away from the coil.
• After switching on, wait 15 minutes for the circuit to stabilise (example in-house criterion; follow the equipment manual).
• Keep the speed of the product passing through the coil constant.
• Run the challenge test (section 6.8) at the defined frequency.
• Rejection limit (example in-house criterion): if more than 0.5% of the good tablets or capsules are rejected as metal-contaminated, raise an incident and investigate.

6.4 Operation, model Metaltrap 03

1. Confirm the cleaning is still valid. Remove the “CLEANED” label and affix the equipment status label. Switch on the detector.
2. Before starting, pass the blank, NFE, FE and SS test pieces. For NFE, FE and SS the LED and buzzer must be triggered and the flap must open. The blank must not be rejected.
3. Record the result in the performance check record (Annexure 1) and the equipment logbook. Remove all test pieces from the area.
4. Pass the tablets or capsules through the inlet chute. Contaminated units trigger the LED and buzzer and are diverted by the flap to the reject bin. Good units are collected from the outlet chute in a labelled, polybag-lined container.
5. Check the dedusted product visually. If dust remains, dedust again.
6. At fast speeds some good units may also be rejected. Re-pass the rejected units one at a time to separate good units from contaminated ones. Destroy contaminated units as non-recoverable material.
7. Apply the rejection limit in 6.3 and repeat the challenge test at the defined frequency during the run.

6.5 Assembling the deduster and metal detector, model SS30

1. Fit the gasket ring on the main bush, aligning the dust collection hole, then fit the Teflon ring.
2. Fit the spiral bottom dish on the dust collection dish, matching the keyway.
3. Bolt the SS bottom cover over the spiral bottom dish, aligned with the compression machine discharge chute.
4. Place the SS spiral on the bottom dish and clamp the rod assembly by turning the handle until tight.
5. Bolt the SS cover over the spiral, matching the spiral outlet, and bolt the SS chute to the cover outlet.
6. Fit the acrylic and SS ancillary parts on the metal detector.
7. Connect the power cable to the supply, connect the deduster plug to the metal detector and switch on.
8. Align the unit with the compression machine and set the height with the height adjusting knobs so tablets fall from the discharge chute into the unit.
9. Adjust deduster vibration with the up and down arrow keys.
10. Collect tablets in double polythene-lined HDPE containers after the deduster and metal detector.

6.6 Setting up deduster control and the product, model SS30

1. Make sure all parts are cleaned as per section 6.2 and the main switch is off while assembling. Switch on and wait for the unit to stabilise.
2. From the main menu you can switch to bar-graph mode, where green and red bars show system noise and the signal from metal, according to its size.
3. Press the DD key, then START or STOP until the display shows the deduster status, power and frequency. Adjust power and frequency with the arrow keys and press SAVE.
4. To set up a product, open the menu, go to the product library and choose View/Edit products. Select a product number, then enter the product name, batch number and threshold using the on-screen keyboard.
5. Return to the main menu, select the product, press LOAD and check the displayed details.
6. Run autolearn by passing good tablets through the detector. Tablets collect in the rejection bottle until the system confirms the parameters are loaded.

6.7 Security (user) levels

Passwords and user levels are set as per the equipment manual. The master password is held by the authorised person only and must never be written in the SOP. Operator and supervisor levels are assigned individually and changed only by the authorised person, so that parameters cannot be altered by operators.

6.8 Challenge (performance) test

Pass the standard test pieces through the detector and record the result in Annexure 1: ferrous (example in-house sizes: 0.25 mm and 0.3 mm), non-ferrous (0.3 mm) and stainless steel (0.4 mm and 0.5 mm).

Run the test:

• at the start and end of the operation;
• after every break;
• after a power failure.

Mark a tick for a test piece that is rejected and a cross for one that is not. If any required test piece is not rejected, stop, quarantine the product processed since the last good check and inform QA.

6.9 Cleaning the test pieces

1. Remove dust from each test piece with a dry lint-free cloth.
2. Wipe each with a lint-free cloth soaked in isopropyl alcohol (IPA).
3. Dry with a dry lint-free cloth and record the cleaning in Annexure 1.

7.0 Annexure 1: Performance checks of metal detector

8.0 Records

Equipment usage, cleaning and performance-check records are part of the batch documentation. Under 21 CFR 211.182 each significant piece of equipment needs a log of cleaning and use with date, time, product and batch, signed by the people who did and checked the work. Keep these records at least 1 year after the expiry date of the respective product batch (EU GMP Part I Chapter 4 §4.11, or 5 years after QP certification if longer; 21 CFR 211.180(a)), and longer if local law or the marketing authorisation requires.

Frequently asked questions

Is a metal detector required by GMP?

GMP does not name metal detectors. It requires equipment to be suitable, cleaned by written procedures and records to be kept. A metal detector is one control a site may choose to reduce foreign-matter risk, based on its own risk assessment.

How often should the metal detector be challenged?

Set the frequency in your SOP from a risk assessment and the equipment manual. This example uses start, end, after breaks and after power failure.

What if a challenge test piece is not rejected?

Stop the line, investigate, and assess product processed since the last passing check. Do not resume until the test passes.

Related posts

See also SOP for equipment cleaning in the production department and SOP for operation and cleaning of the compression machine.

References

• US FDA, 21 CFR 211.67 Equipment cleaning and maintenance (eCFR, current as checked October 2026).
• US FDA, 21 CFR 211.182 Equipment cleaning and use log (eCFR, current as checked October 2026).
• US FDA, 21 CFR 211.180(a) General requirements for records.
• European Commission, EudraLex Volume 4, EU GMP Part I Chapter 3 Premises and Equipment, §3.36 (equipment designed for easy cleaning, cleaned by written procedures, stored clean and dry) and Chapter 4 Documentation §4.11.
• Equipment manual of the installed metal detector and deduster.