MATERIALS HANDLING
Conventional multi-ply construction
design and quality of the ply material used to create the carcass. The big advantage Fenner Dunlop has is that it has its own fabric weaving facility in the US. This is where the company has been able to develop a range of unique super-strength fabrics for single-ply belts (Ultra X and Nova X) and the longer established single and dual-ply UsFlex constructions. The carcasses possess a longitudinal rip resistance that is more than five times greater than multi-ply belts of equivalent rating, they also have up to three times greater impact resistance compared with conventional belting. This is quite a breakthrough. So, how does it all work?
IT’S ALL ABOUT THE FABRIC The whole working principle of being able to create advantages from using single and dual-ply belts centres on the fabric. Having already developed rubber cover compounds that are well-recognised as being the hardest wearing and longest lasting, the company’s engineers focussed on the design of the fabric. The starting point
was to ensure that the individual fibres and yarns were of the highest possible quality and strength. Next came the weave pattern, which is where fabric technology becomes difficult to explain. The X Series has (so far at least) three
versions of fabric. Ultra X features a specially woven ‘Crimped warp’ carcass, combining crimped polyester warp yarns with strong binder and filler yarns, creating exceptional strength, stability, and impact resistance. The higher tensile strength Nova-X (available in North America and coming soon to Europe) uses an even stronger crimped warp fabric with binder yarns to lock the carcass, providing excellent rip, tear, and impact resistance under load. The even heavier duty UsFlex employs a ‘Straight warp’ carcass, made of high-tenacity polyester fibres protected by polyamide weft lines. What all X Series fabrics have
in common is that they consist of longitudinal strands lengthwise and heavy strands running crosswise, held in position by a strong yarn. The strands are completely straight in both directions and not interlocked as in conventional
fabric. This allows the weft to float free from the warp. A shock absorber effect is thereby created by dissipating impact energy over a larger area, allowing the belt to withstand the kind of punishment that would destroy a normal multi-ply belt. Arguably even more important is the ability to resist rip and tear damage. When penetrated and being pulled
through a trapped object such as a large, sharp rock, the unique weave design allows the strands to gather in a bundle that can eventually become strong enough to stop the belt or even expel the object causing the damage. Strange as it may seem, synthetic
plies are usually more effective than steel when it comes to minimising the length of a rip. In fact, the UsFlex fabric is so strong that Fenner Dunlop uses it as a breaker ply in its steel cord belts. As one quarry manager was happy to testify, “We used to replace our belts every three to six months before we started fitting UsFlex belts. Now it can be four or five years before we need to fit a replacement.”
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