Metal detectors: Detection sensitivity improved

Loma Systems is highlighting the importance of metal-free zones for ensuring optimum performance of its IQ4 metal detectors.

The metal free zone is an area surrounding the aperture of a metal detector that should be kept free of any fixed or moving metal to avoid a spike in the signal that could cause false rejects and costly downtime. 

The spike can be random or follow a pattern depending on whether moving or non-moving metal is causing the issue. It might also produce symptoms like that of a contaminated belt or walkie-talkie use.

The calculation of a metal free zone varies and depends on two key factors: is it moving or non-moving metal? The only exception to this rule are gravity fed metal detectors that are integrated into fill and seal baggers with a chute going through the aperture. 

Gravity fed systems are normally built with either welded or bolt-on rings, keeping the field aimed up the chute, preventing it from spreading to the structure and causing instability.

Typical examples of non-moving metal include conveyor covers, factory fixtures and other production lines. The calculation is 1.5 x the aperture height so if the aperture is 200mm in height the metal free zone will be 300mm from the middle of the metal detector aperture.

Moving metal might be rollers, motors or personal items and the calculation is 3 x the aperture height. Where the aperture is 200mm in height, the metal free zone will be 600mm from the middle of the metal detector aperture.

The top, back and bottom of the metal detector head do not need a certain distance due to the steel casing blocking the signals. However, 1 x the aperture height can be used although not for larger heads. 

Loma’s IQ4 metal detectors are said to meet customers’ common inspection challenges and to provide major design, performance, usability, quality and flexibility benefits. 

Features include an enhanced Auto Learn functionality, better product screening and more sophisticated signal processing.

Operating between 31 and 882kHz, all metal detectors in the IQ4 range are capable of automatically selecting correct operating frequency so changes in products or packaging that necessitate an alteration in frequency do not require costly and inconvenient operator intervention.  

In line with Loma’s ‘Designed to Survive’ philosophy, the IQ4 Metal Detector horizontal search heads feature a ‘beyond’ IP69K rating as standard. The rating applies to the entire unit, including the distinctive blue liner, brushed stainless steel case and touch screen.

The blue lining makes the IQ4 resilient to tough factory conditions, ranging from vibration and thermal fluctuations as a result of inspecting frozen products to harsh high pressure, high temperature wash-down with corrosive chemical agents.  

An expanded Auto Learn functionality reduces set up time. Loma’s IQ4 also meets IFS, BRC and other strict Retailer Codes of Practice and confirms support for higher compliance as well as providing a platform to ensure compatibility with future enhancements.