Conical mill screens are critical components across a number of industries, from pharmaceuticals and food processing, to chemicals and cosmetics. Their versatility lies in their ability to perform a range of particle size reduction tasks, from coarse milling to fine micronization. A crucial component influencing the mill’s performance is the screen. Selecting the correct mill screen is paramount to achieving the desired particle size distribution and optimising the milling process. This post will explore conical mill screen selection, exploring the different screen types and their applications.
Hanningfield offer a wide range of conical mill screens, crafted with the highest standards of quality and precision, Our team of experts can guide you in selecting the correct mill screen to optimise your process.
Understanding The Role Of The Screen
The screen acts as a sieve, controlling the passage of material through the mill. It determines the upper limit of the particle size distribution. Material that is smaller than the screen openings passes through, while larger particles are retained for further milling. Therefore, the screen’s aperture size and shape directly impacts the product’s final texture, flowability, and other critical characteristics.
Factors To Consider When Choosing A Screen
Several factors should be considered when selecting a screen for your conical mill;
Desired Particle Size: This is the most critical factor. Finer screens produce smaller particles, while coarser screens yield larger particles.
Material Properties: The hardness, friability, and moisture content of the material being milled will influence screen selection. Harder materials may require a more robust screen.
Throughput Requirements: The desired production rate will impact the choice of screen.
Screen Thickness: The thickness of the screen affects its durability and resistance to wear.
Types Of Screen Openings
Conical mill screens come in various shapes and sizes, each with its unique characteristics;
Round Hole Screen: These are the most common type of screen. They offer a good balance between throughput and particle size control. Round hole screens are generally preferred for materials that are not prone to slogging. They are available in a wide range of sizes, making them versatile for a number of various applications.
Square Hole Screen: These screens offer slightly better throughput compared to round hole screens of the same size. They are often used for materials that are more fibrous or tend to agglomerate. The sharp edges of the square openings can help to break up clumps and prevent clogging.
Grater Hole Screen: This screen has one side of the hole raised to create a rasp (much like a cheese grater) which becomes a cutting edge. This gives the screen more of a shearing action for breaking up material. These screens are ideally suited to harder, more ductile or fibrous materials and can be used to create a consistent granular product with minimal fines.
Slotted Hole Screen: These are suited for wet granulation sizing and milling applications. They are ideal for very friable products or heat-sensitive materials that require size reduction. Similar to square hole screens, however these screens produce larger particle sizes.
Conidur Hole Screen: This screen is also designed with a raised hole to create a rasp. However, the conidur screen is able to produce a smaller particle size. This too is designed for the milling of coarse materials that require a more aggressive milling action.
Diffusion Bonded Screen: This screen offers a pioneering design whereby it utilises no adhesive. This therefore offers an ultra-hygienic, GMP solution in conical mill screens. This innovative screen design enables customers to achieve further size reduced particles compared with other standard screen designs.
Choosing The Right Screen For Your Application
Selecting the right mill screen involves careful consideration of the factors mentioned above. With almost four decades experience in milling applications, we have a vast wealth of knowledge in offering solutions to common and niche milling challenges.
Our team of experts are on hand to guide you through the conical screen and tooling selection process. Our wide range of options makes experimenting with different setups possible, while the spacer-less gap setting makes tooling changes fast and easy (<60 seconds to change screen and impeller).
Maintenance & Screen Life
Regular inspection and maintenance of the screens are essential to ensure optimal performance and prolong their lifespan. Worn or damaged screens should be replaced promptly to prevent inconsistencies in the final product.
Crafted to the highest standards of British excellence and precision, our screens are designed for optimal performance and achieve a small, consistent and repeatable particle size. Hanningfield’s conical mill screens are readily available with the necessary pharmaceutical certifications.
We endeavour to keep shipping times to a minimum as we are mindful of the costs associated with halted production. We always recommend to our customers that they keep stock of spares to maximise their up-time. This proactive approach means any disruption to production is significantly reduced.
Get in Touch
If you would like to speak to one of our experts regarding our range Conical Mill Screens and Spares, or you would like a quote for one of our products, send us a message using our Contact Form or call us on +44 (0)1702 549 777.
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