Sieving | Classifying
Modern production methods and high quality standards require high-grade sieving and classification techniques in order to achieve an optimal and clean end product. Custom Powders invested in a number of different techniques in order to enable us to meet the specific requirements of our customers and offers sieving, separation and classifying services for powders and granules. Among others we offer the option of sieving large volumes of powdery granules, micro sieving of powders in the range from 120 – 200 micron with clear-cut off points, air classification of fine powders in the range of 20 – 40 micron in tanker loads. We are of course also in the position to process smaller quantities for you.
Our equipment is specified to the highest quality and hygiene standards, and can be flexibly applied in whatever direction our customer requires. These sieving actions can normally be combined with other processes such as milling, drying, granulating and blending.
Sieving and Classifying techniques
- Sieving
- Classifying
- Specialist sieving
Please download the print version for an overview of our possibilities for sieving and classifying or read more for further information.
Sieving | Classifying
Custom Powders through the years has become an appreciated and reliable partner for the sieving and size separation of powders. We have available a broad range of different sieving, separation and classification techniques and in this area process hundreds of tonnes per year. The main difference between sieving and classification is that sieving enables one to separate more fractions in one go and with classification only one fraction can be separated from the rest of the product. Classification techniques can be used from about 10 micron to 150 micron while the sieving techniques only start at about 75 micron. It is possible to sieve finer but then special sieving techniques need to be applied.
Our equipment is constructed in stainless steel and is set up in processing units that are strictly separated from each other. Products can be received in various types of packaging varying from bulk to big bags to sacks. This is the same flexibility that we can offer for the end packaging. In general we tend to work a three shift system and our equipment is then processing for you 5 days a week, 24 hours a day.
Sieving
Firstly, we work with vibrating or tumbling sieves. These machines are suitable for the processing of difficult to sieve products and achieve a broad sieving range varying from 200 micron to a couple of mm. They are excellent for the sieving of powdery granules in larger volumes. The equipment is suitable for a broad range of products and they provide a very reliable and efficient end result. 
One of the big advantages of this equipment is that several sieve decks can be installed for the simultaneous separation of several fractions.
The second type of sieve we work with is the centrifugal sieve (Kek sieves). These are sieves that are equipped with a rotating mechanical action that feeds the product through a horizontal cylindrical sieve and also keeps the pores of the sieve clean. These sieves are very suitable for powders that are of a more cohesive nature. A Kek can only separate one fraction from the main product.
These sieves can be used independently but are quite often used as a check sieves at the end of a process line in order to remove possible contaminants or for the removal of powder or granules that should not be in the product. The typical sieving range lies between 75 micron 500 microns but larger mesh such as and 4.5 mm is occasionally used.
Classifying
Air classification is a process whereby large volumes of powders are separated by size by means of air. This technique can be used as a stand-alone technique in order to separate larger particles from the finer particles. The big advantage of classifying lies in the fact that it can be a much speedier process than sieving. The disadvantage is that only one fraction can be separated from the bulk of product. The typical particle size range for this technique lies somewhere between 2 and 100 micron.
Specialist sieving:
Custom Powders is very skilled in the sieving and classification of fine powders. In order to perform this service we have available a number of special techniques.
Micro sieving
We do have a lot of knowledge and experience in house when it comes to the sieving and classifying of fine powders. This is a special area where our equipment provides a reliable performance. This applies to sieving in the range of 45 – 75 micron and classifying in the range of 10 – 50 micron. We are looking at the option of expanding in the direction of ultrasonic sieving in order to offer additional services in this area. The advantage of this new technique would be that it would enable us to sieve very difficult to sieve raw materials still in an efficient way.
De-dusting of powders/granules
For the de-dusting of certain course powders, we have available a special vibrating-sieve. This sieve enables us to remove a certain percentage of the smaller particles from your product so that you will get a virtually dust free product that will show better flowing characteristics. This method can also be used to de-dust granules.
We are looking forward to discuss your enquiries in this area and hope to discuss with you what technique best would suit your specific requirements. Top >>