Long Life: Correctly selected polyurethane's can have long life when screening most materials. In addition it is immune to most corrosive materials.

Improved Screening Efficiency: At ambient temperatures polyurethane's exhibit the characteristic elasticity of rubber. It is this property that allows the aggregate being screened more 'bounce' thereby presenting it to the apertures more frequently. This phenomena fulfils both laws governing the theory of screening.

Minimise Downtime: The long life time described above reduces the frequency of unscheduled stoppages due to screening surface failure.

Noise Reduction: Polyurethane's, due to their rubber like characteristics, absorb feed energy impact and reduce noise levels from between five and eight decibels.

High Initial Cost: Polyurethane's used for screening surfaces have tensile strengths from 20 to 50 Mpa. This necessitates an increase in cross sectional area in the construction of polyurethane screening media. In addition, polyurethane's used in the manufacture of screening surfaces are not suitable for large unsupported areas. The addition of steel support frames is therefore normally required either internally or externally or a combination of both. Polyurethane's are manufactured from high cost materials when compared to 'Vibro' spring steel and this, combined with the additional materials described above, places the initial cost of installing polyurethane at least five times greater than the equivalent 'Vibro' screen cloth.

Open Area: Due to the increase in cross sectional area described above, the resultant number of apertures for any given length, when compared to woven wire screencloths, is reduced.

Aggregate Sizing: The high cost of polyurethane screening surfaces can restrict the range and versatility of screening normally available by changing woven wire screencloths on vibrating machines.

Operating Temperature Range: Polyurethane's are designed to operate at ambient temperatures, this is due to the chemical chain that makes the resultant material, in general most polyurethane's will operate up to 80°C before undergoing a structural change in their chemical make-up. This change normally results in a major deterioration in the quality of the polyurethane.

If an application exists where ambient will be exceeded, careful consideration should be given to the type of polyurethane to be used.

NOTE: Due consideration should be given to the basic laws governing screening and screening efficiency when deciding to change from woven wire screens to polyurethane screening surfaces.

It has been shown in most cases that screening efficiency is reduced by up to 30%, resulting in lower throughput and higher recircular loads. The end result is higher maintenance costs for lower throughput and the need to run the Plant for additional hours to process the required tonnage's, resulting in an unacceptably high cost per tonne. Whilst the actual cost for the screening surface is reduced, this reduction does not in any way compensate for the additional costs incurred.

When the effects of chemical attack will necessitate the replacement of the screening surface prior to the effect of wear.

When the material is subject to microbiological attack.

When screening aggregates that are highly acidic or alkaline.