What is the difference between metal detection and X-ray inspection?

A metal detector finds ferrous and non-ferrous metal by disturbing a balanced electromagnetic field. An X-ray system finds metal, glass, stone, bone and some dense plastics by density difference, and can also check completeness and mass. X-ray inspects the conductive products that defeat basic metal detectors.

Do I need a checkweigher?

If the fill weight is regulated, a checkweigher is not optional — it verifies every package against the destination market's framework, such as the EU MID / OIML R51 and WELMEC 6.5, or NIST Handbook 44 in the US. Even without regulation, it prevents product giveaway.

Why does inspection sensitivity depend on the product?

Conductive products such as meat, cheese and brine are harder to inspect with a metal detector than dry foods. X-ray depends on density rather than conductivity. Always test detection sensitivity on your actual product and packaging, not a reference sample.

Where should inspection sit on the line?

Inspection after sealing catches contamination introduced upstream; inspection before sealing may be needed for product that is then sealed. The point is chosen against the risk you are trying to catch and the reject-and-remove workflow you can support.

Packaging Machinery · Equipment category

Inspection Systems

Quality control machines that detect contaminants, verify weights, and check seal integrity.

Best for: Food safety compliance, pharmaceutical regulations, and brand protection.
Common formats: Metal detection, X-ray imaging, checkweighing, vision systems.

Inspection is not one machine

Inspection systems are the last check before a package leaves the line — and they answer different questions. A metal detector finds ferrous and non-ferrous metal; an X-ray system finds metal, glass, stone, bone and dense plastics by density; a checkweigher verifies weight; vision checks the label and visible defects. Choosing the right one starts with naming the risk you are actually trying to catch.

The technologies

Metal detection passes the package through a balanced electromagnetic field; X-ray measures density and flags anything denser than expected; checkweighing weighs every package in motion against legal or cost tolerances. A conductive product such as meat, cheese or brine defeats a basic metal detector and pushes you toward X-ray or a product-compensated detector.

Selection factors that decide the system

What you are catching: metal-only, or also glass, stone and bone?
Product conductivity: conductive products change the metal-detector choice.
Weight compliance: regulated fills need a checkweigher against the destination market’s framework.
Where in the line: after sealing catches upstream contamination; before sealing may be needed for some products.

Choose the supplier on demonstrated sensitivity

Start with the Top 10 Product Inspection System Manufacturers ranking, and see How Product Inspection Systems Work for the principles. Ask each supplier to detect a known test contaminant on your product at line speed before you buy.

Form-Fill-Seal (FFS) Machines Filling & Dosing Equipment Sealing & Closing Machines End-of-Line Packaging Labeling & Coding Inspection Systems

Decision guides

Start with this guide

Top 10 Product Inspection System Manufacturers (2026)

An independent ranking of the top product inspection system manufacturers across metal detection, checkweighing, X-ray and vision inspection, with cited specifications.

Read the guide

Representative equipment

Product

Mettler-Toledo Safeline Metal Detector

Conveyor metal detector from the Mettler-Toledo Safeline brand for contaminant detection in food and pharmaceutical lines.

Aug 27, 2026 · 1 min read

Technical reference

Knowledge

Knowledge

How Product Inspection Systems Work: Metal Detection, Checkweighing and X-ray

The working principles of metal detection, checkweighing and X-ray inspection, and why inspection is a separate machine decision from fillin...

Aug 17, 2026 · 3 min read

Frequently asked questions

Common questions

What is the difference between metal detection and X-ray inspection?: A metal detector finds ferrous and non-ferrous metal by disturbing a balanced electromagnetic field. An X-ray system finds metal, glass, stone, bone and some dense plastics by density difference, and can also check completeness and mass. X-ray inspects the conductive products that defeat basic metal detectors.
Do I need a checkweigher?: If the fill weight is regulated, a checkweigher is not optional — it verifies every package against the destination market's framework, such as the EU MID / OIML R51 and WELMEC 6.5, or NIST Handbook 44 in the US. Even without regulation, it prevents product giveaway.
Why does inspection sensitivity depend on the product?: Conductive products such as meat, cheese and brine are harder to inspect with a metal detector than dry foods. X-ray depends on density rather than conductivity. Always test detection sensitivity on your actual product and packaging, not a reference sample.
Where should inspection sit on the line?: Inspection after sealing catches contamination introduced upstream; inspection before sealing may be needed for product that is then sealed. The point is chosen against the risk you are trying to catch and the reject-and-remove workflow you can support.