Sieve technology dates back to Ancient Egypt. Understandably, sieving equipment has diversified and developed significantly since then and there are now numerous technologies available for filtering and sorting product. Here, Stephen Harding, managing director of industrial sieve manufacturer Gough Engineering, looks at the different types of sieve construction and where each should be used.
Liverpool Museum has an exhibition of a sieve that was made around 1,500 BC, which was used to separate liquid from mash in the brewing of beer. The historic piece of equipment can be used in a variety of applications in industry.
In more modern times, sieves are used across almost all industries, particularly to classify and sort products. Vibratory sieves are often used to sort rawmaterials such as powders and ingredients through different mesh aperture sizes, ensuring the end product is of a uniform size.
The importance of quality sorting through sieves is highlighted in fields such as injection moulding. As part of the process, the pellets must all be melted at a particular temperature, to achieve uniform shape.
If the pellets are not classified correctly to ensure that they are all the same shape and size, allowing them to subsequently melt evenly, then the whole injection moulding process is ineffective as the end product will not meet quality standards in its material integrity and surface finish.
There are many different designs and ways to manufacture sieves to guarantee the classification of raw materials are sorted effectively. This all depends on the application and what the objective of the sieve/separator might be, dictating the type of sieve being used. For example, air bellows suspension units is are used on certain Vibrecon circular vibratory sieves, as they allow the machine to have better vibrational control in the horizontal and vertical planes — as opposed to springs.
Linear screens are also used to classify or separate particles as a product material moves along a feeding line. This type of screen can be more beneficial for certain manufacturers on heavy duty large bulk handling screening.
For some applications, Gough Engineering uses flexible ROSTA mounts allowing a safer, unlockable connection between deckware and support frame, while reducing damping vibration and arresting irregular and unpredictable behaviour.
A customer that Gough Engineering recently worked with had additional safety requirements in order to mitigate personnel risks as the machine was suspended located four meters above ground, so the ROSTA mount was specified. In this case, the company needed to sort carbon fibre strips. Due to the complex layouts of many factories, it is always advisable to consult with experts before buying an off-the-shelf screening or conveying product and hoping it fits with the plant layout.
There are now so many potential configurations for sieves that it is always best to consult an expert. While the ancient Egyptians may not have had this option, plant managers should discuss plant layout and the application required, before investing in any equipment.