In some applications, especially in primary and secondary crushers, even the strongest and heaviest conventional belts can be torn or shredded by large heavy, sharp objects falling from a height or getting stuck.
UsFlex: Long Lasting Conveyor Belt with Tear and Impact Resistance
Tapes can often be destroyed in a matter of weeks or months. Dunlop’s solution to this problem is UsFlex, which has more than five times the longitudinal tear resistance of multi-ply tapes of equal value thanks to our unique flat warp structure. UsFlex provides up to three times more impact resistance than conventional ply tapes. This unique toughness means that the tape is not easily damaged during loading and transportation of large, sharp materials. As a result, UsFlex will provide the longest tape life in the toughest conditions!
UsFlex owes its outstanding impact and tear resistance properties to an innovative woven flat warp carcass unique to Dunlop. This carcass consists of heavy polyester wires running lengthwise and heavy nylon wires running crosswise, held in place by a strong yarn. The wires are completely flat in both directions and are not interlocked together as in a traditional tape carcass. This allows the weft to float freely from the warp, thus minimizing the peak of impact and providing maximum protection to the carcass as energy is absorbed over a larger area.
The ‘secret’ behind UsFlex’s incredible tear resistance properties is the use of a unique and innovative ‘flat warp’ woven fabric ply. This is heavy strands of polyester running lengthwise and nylon running crosswise. The wires are completely flat in both directions and are not interlocked together as in a traditional tape carcass. This allows the weft to float freely from the warp. This means that if a sharp object enters the carcass, the nylon cross threads have the strength and ‘freedom’ to come together (gather) and effectively form an increasingly strong barrier. This is a broadly similar principle to the fabric rip-stop breaking ply, but significantly stronger and more effective.
Compared to traditional multi-ply and rigid woven tapes, the impact resistance of UsFlex has proven to be significantly superior. This is because the unique UsFlex design minimizes the peak of the impact and absorbs (dissipates) the energy over a larger area compared to conventional high tensile EP or EPP tape. For example, a single ply UsFlex type 630/1 has the impact absorbing properties of a 4-ply EP tape type 1600/4 or an EPP 1250/2. The graph shows the results of impact tests on 630 rated UsFlex, Solid woven and multi-ply tapes.
The tear resistance of UsFlex, measured according to the international standard EN ISO 505, also significantly exceeds that of conventional multi-ply tapes with comparable tensile strength. Tear and tear resistance tests are only performed on the actual tape carcass, so the top and bottom coatings are always removed. This ensures that the thickness and quality of the coating does not affect the accuracy and consistency of the tests.
For belts operating in harsh conditions, it is even more important than usual to have the strongest possible splice connections while maintaining maximum tensile strength. A conventional step joint or fastener will always create a proportional loss of tensile strength. At Dunlop, we recommend the finger splice method, which creates the strongest and most reliable connection possible (up to 90% of the original tensile strength of the tape).
No problem for Dunlop Steelcord bands! To ensure optimum carcass protection, Dunlop RS sleeves are fitted as standard due to their excellent resistance to cutting combined with outstanding resistance to abrasion. Dunlop RS significantly exceeds the highest abrasion standards for both DIN W and the equivalent ISO ‘D’ standard. Other qualities such as oil, fire and heat resistant coatings are also available. All Dunlop coating grades are anti-static according to EN ISO 284 and are extensively ozone tested in accordance with EN ISO 1431 ozone resistance (50 pphm, strain 20%, no cracking for 96 hours) and are resistant to the damaging effects of ultra-violet to prevent premature failure due to cracking of the tape surface.
Dunlop RS significantly exceeds the highest wear standards for both DIN W and the equivalent ISO 'D' standard.
