Food Metal Detector Troubleshooting: Tips for Fixing Common Issues

Table of Contents

metal detector machine
Accurate detection of metal contaminants proves essential in the food production industry. Facilities use food metal detectors and other systems to keep metal out of their products. When detection systems fail, product recalls, and the resulting loss of reputation threatens the bottom line for these companies.Is the food metal detector in your production facility falsely rejecting safe products? If you’re a company owner with a production line that uses a food metal detector, false signals and other issues cause a lot of wasted time and money. This guide to metal detector troubleshooting will walk you through some of the most common metal detector issues and how to resolve them.

Common Reasons Why Your Metal Detector Is Not Working

Detecting metal contaminants in food products proves challenging due to the various factors that affect how inspection systems function. If your food metal detector isn’t working, one of the following causes may be to blame:

Unsuitable Detection System

Every production line poses its own challenges, and not all facilities use the same types of detection systems. For example, a beverage production line requires a different detection system than a line producing dry foods. While a conveyorized metal detector works well with products packaged in paper, foil packaging requires X-Ray inspection.

If your food metal detector is not working, consider its suitability for your application. Would another detection system work better? Does your product require more than one type of system placed at separate points along the line?

Improper Detector Placement

A single metal detector placed at the end of the production line may prove insufficient for proper contaminant detection. You may need to include a metal detector at an earlier production phase to prevent metal objects from getting into products or damaging machinery.

Surrounding signals also affect proper metal detector placement. Machinery that emits microwaves, radio waves, or high levels of vibration, for example, may interfere with your metal detector.

Product Effect

Surrounding electronics aren’t the only things putting out signals that can confuse a metal detector. Products themselves may emit electromagnetic fields and other signals. For example, products containing a lot of moisture or salt can set off a detector when no contaminants are present.

These varying factors determine the product effect and must be considered while designing an effective metal detector system.

Ground Loops

Metal detectors work by generating an electrical field, but this field can become misshapen and produce false signals due to ground loop interference. Group loops occur when two pieces of metal within the detector’s range touch each other. Common causes of ground loops include nearby equipment touching the metal detector, loose bolts, and worn bearings.

The above issues commonly cause false signals that reject products that don’t contain any metal contaminants.

Lack of Training

To successfully incorporate a food metal detector into your facility, you must provide the proper training for employees. Training helps prevent issues caused by mishandling the equipment and making avoidable mistakes. Be sure that operators understand the detection system and receive adequate training on running and maintaining the equipment.

Food Metal Detector Troubleshooting: Three Main Causes of False Signals

tv without a signal

Metal detectors play a huge role in food safety by alerting manufacturers when small bits of metal make it into food products. False signals occur in these detectors for many reasons, creating unnecessary product waste and lost profits. If your food metal detector gives you false rejections, check these three issues first:


Is your metal detector positioned near other machines that may be causing interference? Machines and devices that emit radio waves, electromagnetic fields, or high vibration may cause interference and false signals.

High current load equipment running on the same power source as your metal detector may also cause false rejections by creating spikes in voltage. If possible, place and power your metal detector away from interference-causing equipment.

Lack of Uniformity

Food metal detectors pick up on metal contaminants by sending a frequency through the product. This frequency responds differently to products of different densities, moisture contents, and materials. If your detector detects false signals, consider if lack of product uniformity could be causing the issue.

For example, if a product’s consistency changes due to a flux in temperature or humidity, the detector may read this change as an abnormality in the product. To counter this, try to maintain product uniformity and reduce factors like temperature and humidity changes.

Conveyor Issues

False rejections sometimes occur because of conveyor system issues. For example, if a small piece of metal becomes stuck in the conveyor, the metal detector may send signals even though there is no metal within the product itself.

These metal fragments come from the mostly metal machinery that drives many production lines. The best way to prevent these issues is to replace old machinery and equipment and maintain a proper maintenance schedule.

Four Tips for Preventing Food Metal Detector Issues

Problems with any complex piece of equipment cannot always be prevented, but you can help avoid the need for food metal detector troubleshooting by keeping the following tips in mind:

Control the Environment

Be sure to maintain a consistent environment to prevent changes in temperature or humidity. The more consistent the external environment, the less likely the detector will produce false rejections. Consider what you can do to stabilize your facility’s temperature and humidity levels.

Avoid placing your food metal detector in a high-vibration area. Slight vibrations don’t typically affect a detector’s functions, but false rejections may result from heavy vibrations and sudden jolting movements.

Invest in the Proper System

Several food metal detectors and other contaminant detection systems exist, but choosing the appropriate one depends on your product and packaging characteristics.

For example, your metal detector won’t do much good if you use metal packaging for your food products. Instead, you need a detection system with X-ray technology to detect contaminants. Be sure to use the best piece of equipment for your purposes to prevent issues down the road.

Commit to Regular Maintenance

Your chosen equipment will likely include a manufacturer-recommended maintenance schedule. Use this as a jumping-off point for maintaining your detection system and put your own maintenance schedule in place based on the specific operations of your facility. Keeping up with regular maintenance is the number one method for keeping food metal detectors working correctly.

Consult the Experts

The best resource for your food metal detector often comes from the manufacturer. Before installing a detection system, talk to the professionals to determine which system is ideal for your applications and how to best integrate it into your production line.

If you already have a detection system, seek advice and guidance from the manufacturer to solve any issues you have. Fixing your problem may be as simple as adjusting the sensitivity setting, or you could be contending with other problems. A manufacturer expert can help you diagnose your metal detector problems quickly and get your production back on track.

Find Food Metal Detectors at TDI Packsys

service engineer in a food inspection company

Food metal detectors keep consumers safe from metal contaminants, but false rejections lead to inefficient production lines and lost money. Keep your production running smoothly when you invest in a detection system by TDI Packsys.

When you trust TDI Packsys with your inspection and package automation needs, we’ll provide expert after-purchase support to keep your metal detector running efficiently. We’ll also provide training so your technicians can expertly run our equipment. Whether you need metal detector troubleshooting for your inspection system or other technical support, we’ll be there within 24 hours (usually 48 outside of the continental U.S.) to help.

Contact us using our online form or call us today at 877-834-6750 to learn more about our food metal detectors and other inspection solutions.

Table of Contents

  • This field is for validation purposes and should be left unchanged.