Vibrating Screen

Applications

The design of screening equipment has, over the years, largely been determined by experience and the need to provide good screening capacity and efficiency whilst using the smallest possible screening surface or area. Our standard range of vibrating screens represents the culmination of many years of experience in the handling of a wide range of  bulk materials in a  diverse range of industries. In addition to the standard range of screens there are also many special screens  which have been designed and manufactured to suit customers special requirements. All the screens are designed to give a long working life with minimal maintenance and easy replacement of screening decks. Screening, extraction and separation are amongst some of the most important functions in processing technology and can be divided into several discrete categories and generally defined as:-

Coarse grading – Where bulk materials are divided into course granulation ranges and where in some cases extreme sizing accuracy is not required.

Fine grading – Normally associated with particle sizes les than 3mm down to 50 microns and where a high degree of accuracy is required.

De-dusting and the extraction of undersize particles – The cleaning up of bulk materials by the removal of particles less than the granulation range which, in the main, have been caused by degredation.

Protective screening and the extraction of oversize particles – The removal of impurities, foreign bodies and lumps which greatly exceed the required granulation range.

Separation – The removal of course material from fines.

De-watering – The recovery of solids from a washing media, usually water.

Extraction – The removal of non soluble impurities from washing water or carrier liquids.

Mode of Operation

 Unlike systems using circular or elliptical motion which have to be declined to impart a conveying component into the product being screened, our range of vibrating screens have a predominantly linear displacement which, due to its angle to the screening plane, imparts a conveying component into the product. This not only allows this type of screen to be installed and operated horizontally, but also offers the following significant advantages:-

• High screening capacity
• Practically no wear on the screening deck
• Excellent separation effect
• Minimal pegging and blinding
• Shallow construction

Construction

There are two basic types of body designs. An open construction where the undersize product discharges directly through the screening deck into either a storage hopper or onto a collection conveyor, an enclosed construction where the undersize product falls onto a conveying pan built into the screen structure and is conveyed and discharged through a spigotted outlet on the underside of the screen.

The screen bodies are generally manufactured in either carbon steel or stainless steel or a combination of both. They are designed to be light in construction while still possessing the strength and wear resistance necessary for a long working life.

 Screening decks are supplied according the the requirements of each specific application from a wide variety of constructional designs using the wide range of proprietary screening surfaces currently available.

Bolted or quick release dust tight covers can be fitted where dust emissions, atmospheric pollution or product contamination are to be prevented.

the complete range of screens can be manufactured in accordance with the hygiene and legislative requirements of the food and pharmaceutical industries.

A range of equipment finishes are available which includes spraying, powder coating, polishing and bead blasting.

Drive Units

These are either vibrator motors or electromagnetic vibrators, but as screening performance is greatly influenced by the dynamic characteristics and control parameters of the drive system, the choice between vibrator motors or electromagnetic vibrator drive is very important. The merits of both types of drive systems are given below.

Vibrator Motors

• Linear or elliptical displacement depending on the number of drives
• High output force / weight ratio
• A wide range of fixed frequencies
• A wide range of amplitudes
• Simple an inexpensive connection to the mains electrical supply

Electromagnetic Vibrators

• Easy and stepless adjustment of the oscillation amplitude
• Accurate and repeatable setting of the oscillation amplitude
• The units have no rotating parts and therefore have a long service life with little or no maintenance.
• Full performance is virtually instantaneous when switching on and stops in a fraction of a second when switched off

Suspension Mounts

These can take one of four forms, bonded rubber mounts, hollow rubber mounts, helical coil compression springs or helical coil tension springs. The type of mount is selected to suit the requirements of the installation and to provide a minimum isolation efficiency of 95%.

Product Presentation

It is always recommended that screens are fed with a suitably designed electromagnetic drive feeder as the output can be steplessly adjusted. This ensures that the screen deck can be fed over its entire width with a loose curtain of material at an optimum flow rate, resulting in efficient screening and even wear.

Product Testing

It is not always possible to select the type of screen best suited to a particular application from the description of the material and the performance criteria required. Therfore in many cases optimum sizing of equipment can only be determined by performing tests on a sample of material using our purpose built test units.