MATERIALS HANDLING C
onveyors are indispensable but expensive pieces of equipment. With operating budgets under continuous
scrutiny from senior management, it is all too easy to make a costly mistake when buying conveyor belts. Here, conveyor belt specialist Jeremy Clark shares what he considers to be the most important dos and don’ts when buying industrial conveyor belts.
CHECK THE SPECIFICATIONS Never assume that the specifications of your conveyor belts are correct. Most conveyors have been in operation for a number of years. During their lifetime they are likely to have been operated by several different managers and maintenance personnel. It never fails to surprise me to find that mistakes have been made by the original builders of the conveyor when calculating the belt specification best suited to the conveyor. Likewise, subsequent attempts to solve problems such as rapid wear and ripping and tearing, may have resulted in the wrong specification of belt being fitted. The same applies if the material mix or volumes have changed significantly. It is imperative that the belt specification always matches the conveyor design and the materials being conveyed.
The first signs – small cracks appear in the surface of the rubber For example, belts that are too thick
for the design of the application can cause problems such as excessive rigidity (lack of troughability) and steering and handling difficulties. The same applies to tensile strengths that are too high. It is important to remember that for every step increase in tensile strength, the pulley and drum diameters need to be increased by 25%. The belt carcass may fail due to dynamic stress if this action is not taken. Quality belt manufacturers and their service partners who supply and fit their belts, will have experienced engineers. When provided with sufficient information, they can verify the belt selection.
Too soon on the scrapheap – the price of the belt will invariably be reflected in the length of its working life
SELECT BELTS BASED ON DURABILITY Always select belts based on their durability, suitability and longevity (whole life cost) rather than for short- term ‘economic’ or budgetary motives. Experience shows, without doubt, that the price of the belt will invariably be reflected in both its quality of performance and the length of its working life. I regularly see cases where a good quality belt can produce a working life of more than five years compared to low-grade belts that have been purchased on the basis of their low price but need regular repairs and then have to be replaced after only a year or two, often less. The biggest source of low-price, low-grade belting is, of course, the
Far East, primarily China. Their prices may be very tempting, but it is important to understand how those prices are achieved. The ‘lower labour costs’ argument is a fallacy because the labour element accounts for as little as 5% of the production cost. The true reason for the difference in price is that raw materials make up to 70% of the cost of producing a conveyor belt. Consequently, the only way to manufacture a low-price belt is to use low-price (low grade), unregulated raw materials. There simply is no other way. Cost-cutting practices include using cheap, low-grade carbon black made by burning old car tyres, the use of ‘bulking fillers’ such as clay instead of good quality polymers and using low-grade inner synthetic plies. The two best indicators of poor quality rubber are its low price and its pungent smell. Good quality rubber rarely has any smell at all. As the old saying goes, price is what you pay but cost is what you spend.
CHOOSE BELTS IN THE STANDARD STOCK RANGE Always (unless significant quantities are involved), choose belts from within the manufacturers standard stock range whenever possible Any deviation from the standard specification of a belt held in stock means that the belt would have to be made to special order, invoking higher production costs and potential
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