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Ensuring HACCP compliant inspection solutions

13 March 2022

Peter Walker offers advice on choosing the right product inspection solution, to ensure it complies with your Hazard Analysis and Critical Control Point (HACCP) plan. 

Foreign body inspection is a mandatory critical control point (CCP) in any food factory and in the majority, if not all cases it will involve either a metal detection or an X-ray. It is important to select the correct systems and operate them correctly to practice due diligence and to have trouble free, reliable systems.

Choosing a metal detector
Right at the start it is important to choose the correct metal detector for the application. Some of the necessary questions to ask include:

• Do you need a reject system or just an alarm and belt stop? The biggest considerations relating to this is product size – is it too big or heavy to easily reject and are there any particular retailer codes of practice with which you need to comply.

• Is the aperture size correct? An oversize aperture will decrease sensitivity, so while it may be tempting to just go a bit larger for future proofing, an auditor will want to see that it is correctly sized for your current largest product.

• Does the system have an audit trail where changes and rejects are recorded against a user?

• Can the system connect now, or in the future, to external reporting systems?

• Make sure the manufacturer carries out a performance validation (PV) test so that you have validation of the system.

Choosing an X-ray solution
In the same way, if you choose an X-ray system for your foreign body control or are required by your customer to use one it is important to get it right. It should be the right size for the package and the right type for the product.

Be aware when specifying the package size for an X-ray. All three product dimensions matter on an X-ray, it is not as simple as whether it physically fits, it has to fit within the geometry of the beam too which is not square. Adding a bit for future possible pack sizes can be costly. Adding a few millimetres more to a metal detector costs maybe one or two hundred pounds, if you end up upgrading to the next size X-ray unnecessarily it will cost a lot more!

If tall, unstable packs need to be inspected then specify a side beam machine, even if the packaging is non-metallic. Side beam has several advantages for this type of pack, it allows the conveyor to be run continuously through the X-ray, therefore avoiding pack transfers which can cause toppling. Although this is a more costly system, due to containing X-rays in a different plane, it is the correct technical solution. Avoid being convinced that a less costly vertical beam machine will do the same job. 

Some manufacturers offer a chicane layout for side or horizontal beam X-rays which also allows for less curtain which can also cause toppling. This is achieved by removing the line of sight of the X-rays, which does require more complex shielding, but allows the product a freer passage.

From an inspection point of view an image of the side will be a much more consistent image – compare the side view of a jar with a top view and you will see that this makes sense. The more consistent the base image the better the detection possibilities. For a cardboard tube this still works best and at the other end of the scale for a glass jar it would be mandatory to use a side beam machine.

Check what other features are available that help to justify return on investment (ROI), such as checking for missing product, checking the presence of inclusions, checking lids are on correctly and checking the ratio of components within a pack.

Finally, as with metal detection, check that everything required to meet your customer’s code of practice is available and specified.

These are just some of the basic considerations when choosing inspection equipment. It is always advisable to consult with a specialist before making any decisions.

Peter Walker is sales manager UK & Ireland for Minebea Intec.

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