Industry Blog

Process Tips: Selecting the Correct Screen and Impeller


Round Hole Screen

Round hole screens are used in the vast majority of cone-milling applications.  Typically used for the size reduction of free-flowing materials such as granules, small lumps and powders can be easily milled through the round hole screen.  A wide range of screen meshes are available, in different size and with different apertures.


Grater Screen

The surface of the grater screen will create a shearing action for breaking up the material.  Typical applications for a grater screen include seeds, and hard products which are trying to be reclaimed, such as tablets or sweets. Failure to correctly identify the need for a grater screen can result in the generation of more fines or can severely damage the screen.


Square Hole Screen

Large aperture ‘square’ hole screens are mainly used for coarse milling applications such as deagglomeration of fruits or for producing flakes of material.  The square hole screen is also suitable for wet-milling (moist) applications such as de-lumping of wet mass granulation in pharmaceutical processing.


Round Bar Impeller

A round-bar impeller is a general purpose impeller normally used with standard round hole or square hole screens. The edge profile of the round bar impeller gives a gentle crushing or pushing action against the material during milling.


Square Bar Impeller

The square bar impeller design is used in most cases where a grater screen is required. The sharp edge of the impeller profile provides a sharp ‘cutting’ action helping to break up hard particles. In some cases, both the square bar impeller and grater screen can be surface hardened to give an extended life.


Contact Us

Hanningfield manufacture a wide range of mill screens and impellers, and can replicate any existing parts you already have if you are seeking an alternative supplier.  All parts are made in the UK.

For more information on our screens and impellers, please contact us.

Or to learn more about our cone mills themselves, click here.

Food Cone Mill

Size reduction is a major part of food processing. Most ingredients or products undergo some form of powderisation, deagglomeration or delumping before they become a finished product.

In cone milling, the material is fed through the in-feed chute, using either gravity feed (manually or automatically operated) or by using a vacuum. The material is forced downwards towards the rotating impeller (see picture below), where the centrifugal force pushes the material through the screen, in the required particle size and shape.

Above: Food Cone Mill Grinding Red Peppercorns
Above: Food Cone Mill Grinding Red Peppercorns

Once the material has passed through the cone mill screen, it falls can either fall into a receptacle ready for storage, or automatically flow to a downstream process, offering excellent processing efficiency.

The cone mill can be used for a wide variety of applications in food processing, such as powder or breadcrumb manufacturing, product reclaim, the deagglomeration of food (such as raisins and other dried fruit), the delumping of powders and the size reduction of herbs, spices, flakes (see picture below).

Above: Finished Product of Milled Red Peppercorns
Above: Finished Product of Milled Red Peppercorns

A cone mill is an extremely common and effective method of size reduction in food processing, as it is capable of achieving a high throughput and consistent particle size. The Hanningfield Uni-Mill cone mill also generates low levels of noise and dust, offering significant operating advantages. Importantly, the Uni-Mill also offers an ‘easy-clean’ design, making strip-down and cleaning between processes simple. Manufactured from stainless steel, the Uni-Mill cone mill (pictured below) is a high-performance, low maintenance and extremely hygienic system for size reduction in food processing.

Food Cone Mill
Above: The Hanningfield ‘Uni-Mill’ Food Cone Mill

For more information on the Hanningfield Uni-Mill cone mill click here. Alternatively, to contact a member of our technical sales about using the cone mill for food processing, simply click here.

Cone Mill

A cone mill is an extremely effective machine for size reduction. The advantages of a cone mill over other forms of size reduction mean it is widely used in the pharmaceutical, food, chemical, cosmetic and associated industries.

Above: Cone Mill Screens
Above: The Hanningfield ‘Uni-Mill’ Cone Mill

So-called because of the screen shape (pictured below), a cone mill can offer great adaptability in terms of throughput, particle size, particle shape and many other factors, simply by changing the type of screen or impeller; for example, a screen with a smaller hole size will produce a smaller particle size.

Above: Cone Mill Screens
Above: Cone Mill Screens

Material is fed into the cone mill through an in-feed chute. This can either be charged into the mill using a vacuum or gravity feed. The material passes to a rotating impeller which forces the material through the holes in the screen. Once the material has passed through the screen, the finished product falls from the bottom of the mill to a receptacle beneath.

The cone mill can be used for a wide variety of applications.  In pharmaceuticals, they are often used for wet/dry granulation, tablet reclaim etc., in chemicals the are often used for deagglomeration, in cosmetics it can be used for fine grinding and in food it can be used for deagglomeration, product reclaim and general size reduction.  For example, seeds or nuts (such as almonds, pictured below) can be ground to a smaller particle or even a powdered state.

Above: Cone Mill Screens
Above: Almonds which have been ground in the ‘Uni-Mill’ Cone Mill

For more information on the Hanningfield ‘Uni-Mill’ cone mill click here.  Alternatively, to contact a member of our technical sales for assistance, simply click here.

Pharmaceutical Mill

Milling is an important stage in pharmaceutical processing, and is commonly used for wet and dry granulation sizing, tablet and capsule reclaim, double compression and many other applications.

Hanningfield manufacture a range of conical mills for the pharmaceutical industry - these range from R&D lab mills to full-size, production scale machines.  The conical mill offers many advantages over other milling methods, including low heat generation, minimal dust, higher throughput and adaptability for use on different products.

Hanningfield has more than 20 years experience in pharmaceutical size reduction and the Hanningfield Uni-Mill is designed and manufactured by Hanningfield in the United Kingdom.

For more information on Hanningfield’s pharmaceutical mill, click here.

Hanningfield in EPM Magazine (Page 31) November/December Issue 2010

Hanningfield are pleased to be in this month’s EPM Magazine, with an article about our Uni-Mil lab cone mill, and how it can be used to scale up to full-size production processing.

To see the editorial either turn to Page 31 of the magazine or click the thumbnail below to view the article.

Hanningfield have more than 20 years experience in pharmaceutical size reduction. The Uni-Mill is designed and manufactured by Hanningfield in the United Kingdom.

For more information on the Hanningfield lab size Uni-Mill, please click here.

Leading Technology in Powder Processing

The processing of powders has always been an important challenge for engineers in the pharmaceutical, food and chemical industries. The size reduction milling of powder to create an evenly distributed, repeatable end product is vital as inconsistencies between batches are unwelcome and can be potentially dangerous.

Hanningfield’s conical mills offer a high-throughput solution to these problems, by offering a fast, repeatable size reduction method for the processing of powders. For more information on the Hanningfield Uni-Mill, please click here.

Fine Milling of Powders

The milling of bulk material to a fine powder is vital to creating a quality finished product.

By milling raw material to a fine and consistent particle size, lumps, bumps and irregularities can be removed to product an excellent and repeatable finished product.

The Hanningfield Uni-Mill offers many great advantages for the processing of powders.  For more information, please click here.

Wet Milling of Powders

The size reduction of powder is an essential part of material processing - this can be especially true prior to drying.

Through wet milling, lumpy and uneven powder can be reduced to a uniform particle size.  This results in a faster drying time as the surface area of the material is increased, and will also benefit the quality of the finished product.

For more information on Hanningfield powder milling equipment, please click here.

Conical Milling Brochure

If you are interested in the Conical Mill, then why not take a look at our online brochure?

Its based on Conical Milling alone and it gives information about the machine and what it does etc.

To view it click here.

Hanningfield

Uni Mill: Method

Method of Operation

Unprocessed material is loaded into the product inlet of the Uni-Mill by hand, gravity feed or vacuum transfer.  The material then passes into the milling chamber where a rotating impeller forces the unprocessed material through a stationery cone-shaped screen by a vortex action.  The material is instantly reduced in size as it passes through the holes in the screen.

By changing a combination of screen, impeller shape and speed, the finished milled particle size can be carefully controlled.  Most important for hygienic requirements, such as those in pharmaceutical and food production, there is no metal-to-metal contact between the impeller and screen.

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