Overcoming issues with traditional grate magnet systems

Magnattack Global

Wednesday, 06 June, 2018


Overcoming issues with traditional grate magnet systems

Grate magnets are popular systems for removing foreign metal fragments from food processing lines. Suited to dry products, they are often installed in seeds, grains, sugar, coffee, rice and other similar ingredients.

The term ‘grate magnet’ typically refers to a magnet system in which multiple magnet bars/tubes are configured in a grid-like arrangement within a stainless steel frame; however, there are many variations of the system available. Some of these include:

  • circular grates
  • square/rectangular grates
  • centre-support style grates
  • single-row grate magnets
  • double/multiple row grate magnets
  • grate magnets in housings
  • rotating grates
  • manual-clean systems
  • automatic self-cleaning systems.

Manual-clean designs rely on operator cleaning schedules (some systems feature magnet sleeves or wiper seals, which are not recommended), whereas self-cleaning systems automatically remove collected contaminants from the magnet bars.

Over the years, some magnet designs have advanced in order to better suit customer needs; however, others, such as the traditional framed grate magnet, have not changed as much. They are still one of the most widely used systems to remove metal from dry products... but this doesn’t mean they are not without their own problems.

Traditional grate magnets vs RAPIDCLEAN Grate Magnets

Manual-clean grate magnet designs of the past are often heavy and cumbersome to handle — meaning that operator safety is at risk during cleaning procedures. The Magnattack Global R&D team created the RE80 RAPIDCLEAN Grate Magnet to overcome issues with traditional grate magnet designs and also to provide increased foreign metal fragment control for the food industry. Its clients have had major success with the system since 2012 when it was first released to the market. In some applications, these systems have proven to last over a decade in use while still maintaining over 10,000 gauss surface strength.

The following information sets out some advantages and benefits of the RAPIDCLEAN Grate Magnet compared to traditional grate magnet systems.

Reduced WHS/OSHA risks

It is not uncommon to hear of injuries caused by handling heavy conventional grate magnets, such as those caused by forcefully pulling grates through sleeves and combined seal cleaning mechanisms. There is also the danger of finger or hand injuries caused by magnets clamping to steel surfaces when they have been removed from their housings.

Although very rugged and robust, the RAPIDCLEAN is a lightweight, self-supporting, easy-clean system. This means that operators are not required to pull heavy grates through common wiper seals nor remove them from their housings for cleaning, therefore reducing safety risks.

Easy, efficient and effective cleaning

The RAPIDCLEAN Cleaning Tool and Tray (complimentary with every RAPIDCLEAN purchase) is the simple answer for regular cleaning and collection of magnetics for interpretation. The Cleaning Tool eliminates unhygienic hand contact and injuries caused by sharp metal fragments.

Individual bar cleaning as opposed to multiple bar cleaning — this not only eliminates the risk of jamming (inherent in multibar cleaning methods) but is also very advantageous in that each bar can be individually inspected to ensure that a clean magnet is being returned to the product stream. Individual push tool wipers are tighter, clean more efficiently and permit less build-up of product. They are proven to be more effective than multibar cleaning methods in applications where the product has the tendency to bind, build up or become sticky.

Non-magnetic stainless steel cones at the fixing ends of the magnet bars enable metal fragments to easily drop off once they have been pushed to the end. These non-magnetic bar ends do not come into contact with the product flow, ensuring that the product maintains maximum contact with +10,000 gauss magnetics for optimum separation efficiency.

RE80 HT models are safe for use in high-temperature applications and can withstand cleaning temperatures of up to 150°C/302°F.

Enhanced product flow

Unanticipated product rate increase and difficult bridging materials can often cause blockage, plugging and flow problems in grates consisting of fixed magnet bars in a frame.

The RAPIDCLEAN’s open-ended magnet bars and optionally adjustable bar centres allow for unexpected increased throughput and increased product-to-magnet coverage versatility, therefore solving blockage and flow problems. An optional vibrating motor retrofit can also assist with breaking up sticky or difficult-to-flow material.

Reduced product leakage

When grates are removed from their housings or the process line, there can be a high leakage of product. The RAPIDCLEAN’s quick-release magnetic door closure provides an even and constant door seal pressure to prevent this problem.

Reduced contamination risks

All RAPIDCLEAN door closing devices are captive in order to prevent contamination risks associated with loose wing nuts and door closing devices. The captive door design eliminates the need for any internal ledges or supports that have the potential to cause product build-up and contamination. This also enables effective throughput and maximum product-to-magnet contact.

Increased product-to-magnet coverage

Larger diameter 35 mm/1.4″ magnet bars for increased product coverage and retention of magnetics. With a larger surface contact area, product dwell time and retention of weakly magnetics are increased as compared to conventional 1″ diameter magnet bars.

Hygienic design

Ledge-free housing interior eliminates the risk of product build-up, which can lead to bacterial growth and contamination.

External drawer support slides for hygienic sensitive applications such as dairy powders, infant formula and hygroscopic product.

Selected models are USDA Dairy Accepted for sensitive applications such as dairy powder, infant formula and pharmaceuticals.

RE80 Magnetics

RE80 and RE80 HT Ultra High Energy Magnetics for increased magnet strength retention over time and proven consistency of magnetic circuit stability.

Magnet elements are both seal welded and vacuum resin encapsulated, optimising strength life and magnet retention over time. RE80 Magnet Elements have been known to retain 10–11,000 gauss strength for 10+ years.

Magnet strength life

Optional DURA-SLIK Abrasion-Reduction Technology (exclusive to Magnattack) can maximise the life of the magnetic separator and greatly reduce cradle-to-grave costs. This technology is especially valuable for magnets installed in highly abrasive applications such as sugar, grain, meat rendering and seed.

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