Latest sifting technology

by Marco Galli
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Through the latest innovations introduced in the milling sector, such as the possibility of extracting roll packs from roller mills and by using stainless steel in the construction of milling equipment, it has been possible to reduce maintenance times and increase sanitation in finished products.

These technological innovations are being utilized in all milling equipment, including the plansifter.

Molds that develop inside the channels by the microclimate, generated by humidity and heat, influence the quality of the finished product.

With the goal of eliminating or at least reducing these problems, and following the principles of replacing wood with stainless steel in sifters, new materials have been introduced and a new design philosophy has been adopted.

The right compromise has been reached by the introduction of a new thermoplastic composite material, which is covered by patent. Such material is known for its good resistance to mechanical solicitations and structural variations.

The thermoplastic material used in sieves can be washed with water up to 70 degrees C, helping to eliminate the accumulated bacteria with the guarantee of a constant and high hygiene level.

The weight of the thermoplastic composite material sieves is the same as wooden sieves. In the sieve insert, it has been possible to obtain profiles more thin than the wood that decrease the weight, carrying also a number of advantages. The first and the most important is the increase of the sifting surface by 12%. This enables millers to reach production capacities that could not be obtained before, with consequent benefits for the entire milling process.

Also, using round shapes enable better product flow, lower stockpiles and, consequently, less maintenance.

Another aspect of primary importance that has been considered since the first stage of design of these new sieves is the requested flexibility to be applied in the schemes of the single channels.

The function of the plansifter also involves the correct separation of the various products and avoiding contamination among separated products, so as to take maximum advantage from the product coming from grinding and, at the same time, guaranteeing the respect of the specifications required by flour, semolina and finished products that are demanded both from the technological and hygienic point of view.

To guarantee good sealing between the sieve and sieve holder, profiles with conical DAP sealants are used to provide a safer product for the end user than the traditional techniques provide.

Furthermore, the use of stainless steel as a recovery bottom of throughs, together with round profiles, guarantees a minimum deposit of materials and the absence of molds for the end user.

Keeping always in mind the dimensional aspect and the various requirements of the end users, Ocrim S.p.A, Cremona, Italy, has created the sifter SFX.


With a new engineering approach, based on the development of the reticular structures, it has been possible to obtain a light machine. For example, the weight of the new version with 10 channels is the same as the previous version with eight channels, but at the same time it looks more solid and rigid. In fact, a well-dimensioned structure is able to resist to the stresses to which it is subjected in the simplest possible way.

Thanks to its geometry, the new structure enables a best distribution of stresses with positive relapse on the entire structure of the machine. Furthermore, the use of new support has required the use of new bearings, dimensioned to allow longer functioning time without maintenance.

Besides the use of plastic sieves, the walls of the cabin are foreseen in isolated panels, with the part in contact with the product covered with stainless steel. This combination guarantees a higher insulation, lower thermal exchange and an environment with less condensation and less favorable in forming molds, especially in such applications where the handled product is high in moisture.

The use of these panels has doubled the interval of time between the maintenance of a sifter’s channel.

Furthermore, the structure and the cabins are of modular type, and the machine can contain 4, 6, 8 or 10 channels with the change of a very few particulars, facilitating the operations of assembly and reducing a lot of limitation in the case of future extensions. The SFX is able to support 80 millimeters eccentricity at 220 rpm with a net sifting surface of 0.45 square meters per sieve with 13.5 square meters per channel, which allows processing of 200 tonnes per day of product in every single channel. Analyzing then the use of the machinery as a flour rebolting system, you can consider capacities of 20 to 25 tph. The use of new materials, new engineering choices and small details have generated a machine able to supply high production, reduced times of maintenance, lower intervention request, and high quality, both from the sanitation and quality point of view. The SFX is an innovation generated by listening to millers and the daily problems they face.

Marco Galli is director of technological development at Ocrim S.p.A. He can be reached at