A Guide to Sieving Machinery

A Guide to Sieving Machinery

At Farleygreene we offer a range of various sieving machines for different purposes. If you are unsure about what each sieve has to offer and would like to familiarise yourself before speaking to a member of our team, this guide will provide you with an explanation of the different types of vibratory and non-vibratory sieves we have available.

You might have heard many different words being used to describe sieving machinery: screening machines, circular screeners, vibratory screeners, and sifters – but broadly speaking, we refer to each of our machines as a ‘sieve’. Many of our customers use our sieves for a variety of purposes, beyond simple screening and separating.

Check sieve 
This is by far the most common type of sieve and bought most frequently by our customers. This type of sieve might be chosen to remove lumps, bits of packaging, or to make sure no insect eggs get into the final product. Overall, this type of sieving ensures the quality of the final product is as good as it can be.

Check sieves are usually a single screen and typically the fine product that passes through the mesh is kept as good product. Check sieves can also be used to remove broken or undersized product as well.

In most applications, a check sieve is either the first machine in a process, preventing contaminates, or the last machine before packaging as a final quality check. However, they can still be placed anywhere in the process line.

Our Slimline sieves are perfectly suited for this type of operation, though our other ranges can make excellent check sieves as well. 

Grading Sieve
A grading sieve is more precise than a check sieve, the goal is to get exact ‘cuts’ of the product where the particles in each cut are between a certain size. This is usually achieved by passing the product through up to 4 meshes with decreasing aperture sizes.

Often, the first mesh is a large aperture size that performs a check sieving operation before the true grading operation, though this isn’t always necessary.

Because the particle sizes are very close to the aperture sizes, the throughput of grading sieves is typically a lot slower than that of check sieves. However, this can be compensated for by having larger mesh areas or finely tuning the motor weight set-up.

As their name suggests, our Multiscreen range of sieves are perfect for this type of application, though some of our other ranges can also be used for grading – for example our E-400-GRV.

Linear Sieve 

Whilst most of our sieves available have circular screens, moving product across the mesh in a rough spiral, Linear vibrating sieves operate on a different principle.

As the name suggests, they move the product in a linear direction, therefore a rectangular screen is used to give the product more time to pass through the mesh. They can efficiently move product and often replace more conventional conveyors as the vibration of the linear sieve gently bounces the product along. The sieve can be inclined to lift the product up to the next stage in the process.

They are especially useful for delicate or friable products, and for products that have a high percentage of oversized particles, as the length allows the fine product a very good chance of separating from larger particles and falling through the mesh. This makes linear sieves especially useful for de-dusting or de-watering operations e.g. removing small loose crumbs and flour from finished biscuits.

Our Linear sieves can be designed with rows of parallel bars instead of mesh, for processing pills and capsules for the pharmaceutical and nutraceutical industries. They can also be configured to have multiple meshes for grading operations.

See our Segregator range which includes a range of different sized of linear vibrating sieves.

Rotary/Centrifugal Sieve

Almost all of our sieves are vibratory, moving the mesh to induce movement in the product allowing it to go through the mesh. However, another popular method of sieving is with a rotary or centrifugal sieve.

These sieves use a set of paddles to push the product out through a cylinder of mesh, rotating them at a high speed and applying a centrifugal force to the product (hence the name!). The cylinder is mounted horizontally, so a slight twist is applied to the paddles to move product down the length of the cylinder, and an auger is used to feed the paddles at a steady rate.

These paddles force product through the mesh giving them very high throughputs compared to vibratory sieves. The motion of the rotating auger and paddle assembly is very good at breaking down lumps or compacted product.

Rotary sieves can only be fitted with a single mesh, so are ideal for check sieving operations. The rotary sieves we have available are listed in our Rota range, and dedicated lump breaking versions are available too.

Vacuum and Pressure Sieves 

Vacuum and pressure conveyors are often a very efficient way of moving product, especially fine powders, through a process line.

Our Slimline pneumatic range can be installed inline with the conveying system, ensuring it remains sealed and preventing the need for additional conveyance systems post-sieve. The movement of the air can help draw the product through the screen and pass it on to the next process.

Due to the complexities of airflow, these sieves are almost exclusively single screen check sieves rather than being used for grading operations. Our Vacusiev and Pressure sieve Slimline ranges are designed specifically for this purpose.

Batch Sieves 

Not all industries or processes require vast factories or continuous production lines.

Batch sieves are recommended for any sieving process where only a small volume or a very short production run is required. It might be that throughput rate is not a major factor in this circumstance so only a small sieve is required to process a set volume of material.

This type of sieving is still considered a check sieving or grading operation, but it is just on a much smaller scale or not a continuous process.

Our Artisan range of sieves is ideally suited for batch sieving operations:

200-S
500-S
E-400-STV
E-400-GRV

Many of our other smaller sieves can also be appropriate depending on the application.

These six categories don’t cover everything we offer at Farleygreene so be sure to take a look at our full range to see what other machines we offer. If you have any questions about any of the information listed, or you are interested in obtaining a quote from us, complete our request form, email us directly at enquiries@farleygreene.com, or call us +44 (0) 1256 474 547 to speak to a member of our team who will put you in contact with your nearest distributor (who you can also contact directly!).

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