Plan Automation Technology Blog

3 Types of Metal Detection Applications for GFSI Audits

Posted by JP Perreault on Mon, Apr 21, 2014 @ 08:04 AM

Metal DetectionModern industrial metal detectors have been described as some of the lesser successful machines in auditing tests and examinations, with up to 75% of audits reportedly encountering some type of non-conformance; however, manufacturers can keep their companies out of this statistic by incorporating proper operator training and accurate record keeping. Effective and standardized testing procedures, and the knowledge of how the three metal detection applications function with regard these procedures, can greatly ease the stresses of the auditing process.

Conveyor Systems - End of Line

For many manufacturers and production line managers, end of line inspection is the leading and preferred stage for completing Global Food Safety Initiative (GFSI) audit compliant testing. It is widely the industry-preferred application because at this point in production, products have already been packaged and there is virtually no risk of additional contaminants reaching the product.

The design of end of line conveyor systems, however, presents manufacturers some performance considerations, including detector performance and reliable rejection. In order to eliminate false positives metal detector  manufactures will suggest installing isolated rollers on conveyors to eliminate electrical loops, as well as a higher quality self tracking metal-free belt system (often plastic) to improve detector reliability and performance; also, a carefully selected reject device ideal to your application product’s packaging size, shape, belt speed and width can improve results with your metal detector.

Reliable reject devices come in a variety of models, specifically tailored for certain jobs, products and production systems, including:

  • Air blast rejection, ideal for light packages and systems with a high throughput
  • Diverter arms, which are ideal for light-medium packaging with medium throughput
  • Pusher/ram rejection devices, most effective with medium to full -sized packaging and high throughputs
  • Stop-on-detect devices, ideal for larger boxes and bulk material, and systems with a slow throughput
  • Retracting band/carriage devices, which are effective in medium throughput systems with small products or irregularly shaped goods

Most of the GFSI audit testing focus is placed on ensuring that rejection devices, and the machines’ detectors, are in correct working order; manufacturers comply to this need by placing test samples at varying locations in products and along product lines, and passing both alternate and successive testing packs.

Further failsafe techniques, such as reject confirmation sensors and air pressure failure notifications, can the integrated with end of line conveyor systems to better perform during GFSI audit processes.

Drop-Through / Gravity Metal Detectors

Drop-through, gravity metal detectors are ideal for the processing and quality inspection of free-flowing dry products, such as grain, flour, rice and plastic pellets etc. In utilizing drop-through/gravity metal detectors in GFSI audit applications, manufacturers must also be aware of the design considerations and issues these machines may create.

Calculating internal dimensions is a relatively simple process, taking into account the flow rate and bulk density of the product. Additionally, manufacturers must consider that round pipes flow more efficiently than rectangular pipe systems, yet rectangular pipe models have shorter lengths due to decreased stroke and reaction times of the reject device. In choosing the optimum system it is important for manufacturers to recognize pipe size and dimensions, valve response times and product speed measured from the feed source  zero velocity free fall height.

Drop-through/gravity detectors can be more challenging to test than other detector systems, but many of today’s models come equipped with testing access and recovery design features, such as models manufactured by Fortress Technology, Inc. As with end of line systems, much of the GFSI audit testing focus is placed on performance of the detector and rejection devices.

For ideal and successful audit applications, many manufacturers make sure that their detector incorporate:

  • Functioning and effective test access port, that allows test samples to travel at the same speed as the product
  • An operational test sample safety retrieval gate, which lets manufacturers and machine testers safely recover sample should the detector fail to isolate the sample.
  • An automatic testing system, which keeps testing consistent and delivers more recurring results with no labour component

In addition, it is important for manufacturers dealing with GFSI audits to consider the presence of static electricity within their detectors, which is often generated by falling dry products. To reduce the interference of static electricity, manufacturers can wrap conductive shields around plastic equipment and parts, properly ground metal parts and equipment near the detector, and assure that detectors have a single point ground.

Pipeline Metal Detectors

Pipeline metal detectors, ideal for scanning liquid products (sauces, dairy and meat slurry), are also commonly tested in GFSI audits, and feature their own common design issues that manufacturers must consider before testing, including:

  • The pipe clamp connection style
  • Product flow rate and viscosity
  • Product temperature & pressure
  • Pipe I.D.

Additionally, it is important for manufacturers to accurately calculate detection system length, and select a valve style and non-metallic piping. Precisely measuring system length is crucial in estimating product flow speeds, valve response rates and safety margins. Selecting a valve type for a pipe system depends on product viscosity and temperature, as models and specialized styles are available to more efficiently perform with certain materials. Choosing the non-metallic pipe itself requires consideration of anticipated product pressure, temperature and style of pipe connection.

Similar to drop-through/gravity metal detectors, pipe detector systems may be more complicated to test than other systems. These systems must also incorporate test access ports and test sample safety retrieval gates to accurately and efficiently perform in GFSI audits. Automatic testing technology can also greatly streamline the pipe system testing process. 

Considering the three metal detection applications for GFSI audits highlighted in this article, it is important for manufacturers to note the special cases and features of each detector type, and know where these machines may face issues in testing. Effective production line managers ensure the appropriate quality and frequency of audit testing remains consistent, delivering  consistent and reliable optimal results.

To learn more about metal detection applications in GFSI audits, or what to consider before testing your equipment, feel free to contact us directly.

Metal Detector Basics for GFSI Audits

 

 

 

Topics: Metal Detection, Fortress Technology, Metal Detection Technology, Metal Detectors, GFSI Audits