Magnetic Plates are separators used to extract ferrous particles and small tramp iron, such as nuts, bolts, nails, bits of wire, etc. from free-flowing materials to protect the machinery from any potential damage. They help to enhance the production process by removing these particles.
These plates can be installed in ducts, sputs, feed trays or conveyor belts of screens, and chutes made with steel or other materials easily. Whether there is food, fertiliser, plastic, or grains, they can remove everything and provide a final product free from contamination.
In this blog, we’re going to look at the basics of magnetic plates so that you can have a better understanding while using them for your specific purpose.
How do Magnetic Plates work?
Magnetic plates are a cost-effective solution for extracting metal particles from the thin layers of a product. You can use lower-strength magnetic plates for lower product flow rates, lower conveyor speeds, and thinner burden depths.
On the other hand, higher strength magnetic plates are good for extracting metals from a distance of up to 6 inches. To remove iron, magnetic plates are placed above the material flow that attracts the iron particles.
During the separation process, the magnetic field interferes in the flow of material and removes the iron when it is passing through the plate. It grips the trapped iron tightly to the plate’s surface so that no particle is left during the cleaning.
The next thing is to isolate ferromagnetic materials like tin & containers from conveyor belts for which multiple magnetic plates are placed at different locations. This prevents the sheets & containers from falling down back to the conveyor.
As a fact, if the magnetic plate is closer to the product, the iron separation will be more effective. However, you must clean these plates at regular intervals to ensure they work properly.
Characteristics of Magnetic Plates
- Cost-effective & robust
- Developed with ceramic or rare earth magnets
- Stainless steel construction
- Ability to be mounted above & below the product flow
- Lightweight & easy to install
- Need no maintenance & user-friendly
- Easy to clean manually
- Excellent penetration strength up to 400 mm
- Magnetic separators capture most of the common ferrous debris
- Ideal for the food industry
Types of Magnetic Plates
1. Standard Magnetic Plates
These plates are made from permanent ceramic magnets or high-intensity rare-earth magnets. They are an ideal choice to capture small metal particles and magnetic debris from powdery, moist & abrasive materials that can choke or prevent magnetic separators from working efficiently.
The plates can be installed in chutes to remove small ferrous particles & bigger pieces of clamp iron from free-flowing materials. They can also be placed below or above conveyor magnetic pulleys to capture particles when the material flows through open belts.
The materials used in their manufacturing are a latch, pre-drilled hinge, and other hardware materials that lead to easy mounting. You can find these plates in widths from 4” to 60”.
- Stainless steel construction along with a tapered face to prevent product wipe out during product flow.
- Food & USDA finishing to ensure production is safe for the industry.
- Suitable for 30 to 60 degree height to attract contaminants when the material flows above the magnetic plates.
- Hinged for ensuring easy cleaning.
- Use of rare earth magnet materials in these plates maximises strength & reach out.
- Manufactured with a replaceable face to deal with hard materials.
- 10k gauss to comply with the food industry standards.
2. Housing Magnetic Plates
These plates are useful to prevent choking to attract ferrous particles & tramp iron when the flow of product materials is in bulk. Constructed with stainless steel, these plates can be mounted to enclosed spouting or to the production equipment. Some adapters (round, square, or rectangular-shaped) can install these plates easily.
- Stainless steel construction to prevent wear and tear and extend the life of the product.
- Self-cleaning facility to ensure it works smoothly.
- Suitable for separating fluffy & flow-resistant particles that restrict the extraction process.
- Available for making transitions for spouting, whether round, square, or rectangular.
- Construction using ceramic & rare earth magnets depending on your needs.
- Fits into small spaces easily, which makes mounting on food processing equipment possible.
- Includes a diverter (removable & replaceable) at the top of housing to direct the product flow over the magnetic plates.
- 10k gauss to comply with the food industry standards.
3. Suspended Magnetic Plates
These plates are suspended above conveyors to remove ferrous particles that are present in food grains, raw materials & processed food, dry powders, etc. without interrupting the product flow.
- Stainless steel construction to qualify for food & sanitary grade standards.
- Robust & high-quality plates along with support frames to allow mounting easily.
- Additional stripper plate slides for faster & easier cleaning.
- Designed with a ceramic magnet field that goes deeper into conveyed material to extract ferrous particles or tramp iron. Also, comes in rare earth magnet material for applications that need higher magnetic power.
- Self-cleaning the plate helps in increasing its efficiency.
- Easy installation.
- Manufactured in several shapes & sizes
Common Applications of Magnetic Plates
Magnetic plates are used widely in the food industry to prevent product contamination & improve their purity. This is because these plates are effective in protecting equipment from any potential damages and wear and tear.
The plates also help to avoid rust & separate trapped iron components in the machinery. Their effectiveness ranges between 70-90%. If you want a purer product than this, multiple magnets can be used.
Below are some of their common applications:
- Food (Tea, Cocoa, Spices, Coffee, Milk Powder, etc.)
- Chemicals & Fertilizers
- Ceramics & Glasses
- Machinery & Foundry Sand
- Cattle feed materials
- Wood pellets
- Electronic waste products
- Pulp processing
Precautions to take while using Magnetic Plates
If you think of welding close to a magnetic plate, it won’t be possible. Due to the interaction between electricity and magnetism, the welding arc acts like a bolt of lightning and goes out of control. So, you must handle it with care.
Also, magnets have the qualities of a diamond. They are very rigid & brittle, so drilling on the magnetic box can damage the magnets, leading to a decrease in their performance.
How do they extract Stainless Steel from the materials?
Magnetic plates constructed with stainless steel contain around 70% iron. These plates may turn non-magnetic with proper alloying & heat treatment. But if these non-magnetic stainless steel materials are torn, the broken pieces may develop magnetism. Rare earth magnets are powerful enough to capture this.
How are magnetic plates designed & developed?
Magnetic plates are made using ferrite magnets or other materials depending on the flux intensity they need. They are constructed in a flat or curved shape as per specific dimensions with stainless steel on their magnetic surface. They are flexible so you can fix them above or below conveyors to catch the contaminants.
Although magnetic plates can be designed in multiple shapes & sizes, they usually have flat & stepped magnetic faces. You can use flat magnetic plates when the magnet will be kept above or near the product flow.
You can use stepped magnetic faces below the product & material flow while excluding fragile products that can be damaged while dropping the step during the process. The steps allow the trash to hide from the product flow while avoiding the brush-off.
The direction of product flow is determined by our plate’s “length”. While the “width” can be observed perpendicular to the product flow and the “depth” shows the thickness of the magnetic plates.
You can ask a reliable manufacturer for the ideal magnetic length & wish as per your product requirements. Usually, additional magnetic length is preferred if the product flow is faster because it gives enough time for the magnetic field to extract contaminants from the product flow.
The thickness of the magnetic plate highly depends on the depth of the materials. If the depths are thicker, the plates are thicker too.
Two types of magnets used in the design of magnetic plates are:
1. Ceramic magnets
These magnets are cost-effective and provide excellent protection. They are perfect for allowing magnetic plates to reach into deeper product flows & extract ferrous particles. However, they cannot extract fine particles as efficiently as rare earth magnets. You can use them at a temperature of up to 850 degrees. Also, the best part is that they hold their magnetic strength for a long time while resisting demagnetization.
2. Rare Earth Magnets
These magnets are made with two materials: Neodymium-Iron-Boron and Samarium Cobalt. They are a little more expensive than ceramic magnets but are helpful in separating ferrous fine particles. Thus, they offer optimum separation performance while allowing for a reduction in the weight & size of magnetic plates. You can use them at higher temperatures of up to 575 degrees.
How can you help with the design?
If you want a customized magnetic plate as per your application requirements, you must give answers to the following questions to your manufacturer:
- What products will flow through the magnetic plate?
- What is the largest size of the ferrous particles?
- What is the highest depth of the contaminants in the product flow?
- How fast will the product flow across the magnetic plate?
- How are you going to install the magnetic plate on the conveyor or chute?
- Do you need any mounting?
- Do you know the dimensions of the materials, such as width, height, length, etc that will be used for brush-off?
The answers to the above questions will help the designer better understand your product requirements. This way, they will come up with the right product to serve your business needs.
How can you help with their cleaning?
Magnetic plates are cleaned by releasing clamps & lifting the magnet away from the chute. If you are using them for applications with a high-frequency of tramp iron contaminants, you can use their self-cleaning models, such as cylinders, to clean them properly. This is also helpful to access difficult areas & remote operations.
How can you improve their performance?
Magnetic plates work better when they are installed under the surface of product flow and not above. So, you need to take care of this to improve their efficiency. However, if it is not possible to place the magnetic plate under the product flow, then you can try positioning it as near as possible.
In addition, magnetic plates perform better when the depth of the product flow is thin, and it is passing slowly past the plates. Hence, you can try to ensure the above factors to increase the performance of your magnetic plates.
Keep a note that if there are fine particles & hard stainless extractions, it may affect the efficiency of the plates.
How can you select the best Magnetic Plates?
You can find magnetic plates in different sizes to meet your specific operations & plant requirements. While looking for them, you must select the ones mounted above the product lines and have flux control to ensure a tighter holding field. These plates have some additional magnets between the poles, which makes the flux lines go deeper into the material flow.
The plates must have a deep penetrating magnetic field, so they can attract iron particles from a distance. The strength of this extraction force depends on the weight of the particles & not on their shape.
Usually, a rod, a cube, and a flat-shaped particle are captured easily while a sphere-shaped particle is attracted with a little difficulty.
The strength required to extract a certain shape is known as the “specific force index”. If you know the force index of a particle, you can evaluate whether it can be captured or not.
At last, select the plates that are highly magnetic on multiple sides. The plates usually extract the contaminants on their magnetic face, so they should have magnetic trailing edges. This provides the extracted contaminants a place to hide so they are not brushed off in the free-flowing material.
Magnetic plates are an appropriate choice to prevent incurring losses due to damage of the machinery or shutdowns and avoid fire & explosions in your production plant. They are economical & durable. You can look for a reliable manufacturer & supplier of magnetic plates to get them for your business’ requirements.
If you are looking for a leading ferrite core manufacturer, Then you can prefer Cosmo Ferrites Limited.