Are Rotary Sieves The Best Option For Bulk Powder Sieving?

With the advancement of new technologies, we compare traditional rotary sieves with modern vibratory screeners to determine which is the optimal solution

With an increase in regulations and quality standards, manufacturers are having to review their processes, and seek new ways to optimise production.

This means a change of approach in the way a factory operates, from how people work or how stock and space are utilised, to the introduction of alternative technologies. These changes lead to improved product quality, efficiency of production, reduced costs and compliance with environmental standards.

Choosing the correct sieving or screening machine is fundamental in ensuring that the product is processed efficiently and to the highest possible quality. There are numerous technologies available, however rotary sifters have commonly been used to remove oversized contamination from good product, particularly for raw ingredients in the food industry.

This is due to their effectiveness at de-agglomerating powders at a high capacity, as well as generally being easy to install. However, compact vibratory screeners now deliver a number of improvements, and these modern alternatives are now seen as the smart option to sieving bulk powders.

Contamination Control

Contamination control is the biggest issue when operating a rotary sieve. In particular, the method of forcing material through the screen in a rotary sifter can cause damage to the mesh, which can be overlooked as the machines are so difficult to disassemble and inspect.

This, as well as the constant loss of good product through an oversize outlet, means having to reprocess material, an unnecessary cost and use of time.

Modern industrial screeners facilitate sieving through a vibratory motion, which is far less strenuous on the mesh, and any ferrous contamination that does enter the pan can be removed by the easy addition of an integrated magnetic grid separator.

Improved Usability

Compared to the design of a rotary sieve, vibratory screeners are considerably more operator-friendly. With a quick-release clamping system, no tools are required to disassemble, meaning that changing the screen or cleaning the machine is quick and safe, reducing downtime.

Also, maintenance costs are reduced, with fewer wearing parts that would have to be replaced regularly. In addition, with it’s a lower noise level (typically 70DBA), and enclosed sieving compartment, the benefits of this machine satisfy the requirements of quality and safety supervisors.

Sanitary Design

Vibratory screeners are designed to provide the most hygienic solution possible. With fewer contact parts, and a fully stainless-steel design, the machine is easy to clean and maintain, an important factor in industries such as pharmaceutical and food (see right, installed at a Nestlé plant in Chile).

Rotary sieves can have many hidden areas and crevices that act as bug traps, and, being extremely difficult and time-consuming to take apart and clean, hygiene cannot be guaranteed.

High Capacity, Compact Design

An inline, compact design makes the vibratory screener half the height of a traditional sieving machine. This makes these screeners easy to install in existing processes, fitting neatly into any part of the production line. Its compact design does not mean a sacrifice in production capacity, however, achieving higher throughput per unit mesh area than conventional screeners.

In some cases, particularly when screening sticky powders, rotary sieves are prone to blinding. Vibratory screeners are better suited to these difficult powders, and the optional upgrade of an ultrasonic fine-mesh sieving system enables even higher screening capacities, as well as accurate grading down to 20 micron. This ultrasonic screening technology prevents mesh blocking and has revolutionised the way difficult powders are sieved.

Russell Finex Ltd
Tel: +44 (0) 20 8818 2000
www.russellfinex.com