MATERIALS HANDLING
whole life cost, it is necessary to understand the methods used to minimise the selling price and their negative impact on the performance and length of operational life.
IT’S ALL ABOUT THE RUBBER It is the quality of the outer rubber covers, in particular the ability to resist wear and tear, that has the biggest influence on the operational lifetime of a conveyor belt. Rubber usually forms some 75% of the volume mass of a conveyor belt and more than 50% of the cost. It is therefore the single biggest opportunity for manufacturers to minimise costs. Te primary cause of rapid belt cover
wear is because low grade ‘economy’ rubber that has inadequate resistance to abrasive wear and cutting has been used rather than using a rubber engineered to provide a high level of resistance and therefore a much longer operational lifetime. Te ability of rubber to withstand
wear and tear also depends on its overall strength and its resistance to cut and tear propagation. If the latter is insufficient then even a small, seemingly insignificant area of damage in the cover can easily increase in size due to the continuous material loading and the flexing around the drums and pulleys. In time, this damage will spread and link up with another area of damage. Consequently, small pieces of damaged rubber are effectively cut out from the surface rather than being simply worn thinner.
LIFE-SHORTENING OMISSIONS Because of its adaptability, most of the rubber used to make conveyor belts is synthetic. Dozens of different chemical
For mining conveyor
belts, longevity and cost are intertwined
manufacturers based in Southeast Asia, at literally half the price of those being offered by the big, quality-led manufacturers based in Europe. However, a big difference in price invariably indicates a comparable difference in the quality of the materials used. Te materials used to make a conveyor belt can constitute up to 70% of its ultimate cost and are therefore the prime target for cost-cutting for those wishing to offer lower prices than their competitors. To better understand the connection between the sales price, longevity and the effect on
components, polymers and substances are used to create the numerous different rubber compounds needed to cope with the different demands that may be placed upon them. For human safety and environmental protection reasons, these chemical components and additives are strictly regulated in Europe. However, such regulation does not apply outside of Europe, including Southeast Asia of course, which is the biggest source of low-price belting. Good quality, regulated raw materials are significantly more costly than low-grade, unregulated raw materials so their use makes an important contribution towards the manufacturer’s cost-cutting objectives. In some cases, despite their enormous influence on the operating life of the belt, some additives are omitted completely because they are seen to be an avoidable cost. One of the best examples of such an omission concerns ozone and ultraviolet light. From a longevity point of view, there is no question that all rubber conveyor belts need to be fully resistant to the damaging effects of ozone and ultraviolet light. Tis is because at ground-level, ozone becomes a pollutant. Exposure, which is unavoidable, increases the acidity of carbon black surfaces and causes reactions to take place within the molecular structure of the rubber. Tis has several consequences including surface cracking and a marked decrease in the tensile strength, all of which accelerates the wear and general degradation of the rubber. Likewise, ultraviolet light from sunlight and fluorescent lighting also accelerates deterioration because it produces photochemical reactions that promote the oxidation of the surface of the rubber resulting in a significant loss of mechanical
Cost-cutting opportunity: rubber resents 70% of the volume and 50% of the cost
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