March 2020

® www.acorn-ind.co.uk T: 0800 8766 441 E: enquiries@acorn-ind.co.uk Your authorised SKF distributor COMPLETE MAINTENANCE SOLUTIONS FITTING LUBRICATION MONITORING Fit bearings safely with SKF TWIM 15 portable induction heater Reduce maintenance intervals and downtime with SKF Automatic Lubrication Dispensers Monitor your machines health and predict failures before they happen with SKF Enlight QuickCollect For further information, or for a demonstration of any maintenance equipment, contact us: n BELTS, BEARINGS AND CHAINS Tips to help keep your belts in business T o avoid the potential risk of belt drive failures and the resulting downtime, it is important to choose a belt that is appropriate for the application. As well as considering how much power will be absorbed, the required running speed, and the service duty of the application, the operating conditions should also be taken into account. For example, if the process is subject to harsh climates or contaminants – as a result of extremes in temperatures, condensation, dust or corrosive chemicals – make sure that the belt can resist the challenges. Tighten it right Belt tension is critical to efficient performance, and more accurate belt tensioning can increase belt lives by up to 50%. Just 5% under- or over-tensioning can result in premature failures. Tension values are calculated scientifically according to variables such as the type of drive, absorbed power, how much pressure is exerted on the belt, how much movement it deflects, and the number of belts installed and pulley sizes. So tensioning a belt based on the traditional method of “twisting a belt half-a-turn” is simply not adequate. If a belt is under-tensioned, it will slip in the pulley. This generates heat and increases the risk of secondary curing. Conversely, an over-tensioned belt introduces more wear in mechanical components such as bearings and motor shafts. To ensure belts are tensioned correctly, you should use gauges and tighten the belts to the manufacturer’s recommended values. Remember, friction belts need to be re-tensioned 3-4 times during their average three-year lifetimes. Get slack Best practice dictates that you should slacken the tension when fitting a belt. Never lever it on with a screwdriver or crowbar, because this risks damaging the belt and/or the drive. Always check the amount of belt deflection at installation, and that it has been aligned correctly using a laser tool – not by eye. Replace worn pulleys It is estimated that around half of new belts are fitted to worn pulleys, wasting energy and shortening the lives of the new belts by up to half. Replacing a worn belt but leaving a worn pulley in place will do little to restore the efficiency of a drive, and the belt will have a far shorter lifecycle than it should. For optimum performance, pulleys need to be changed at every third belt change. Time it well Although friction belts are the traditional choice, timing belts have advantages in some applications. They never need re-tensioning and maintain 98– 99% efficiency for their whole three-year design lives. Therefore, it can make financial sense to choose timing rather than friction belts for existing and new applications. If you are choosing a timing belt, you will also need to replace the pulleys – but that will lead to additional gains. For example, a single timing belt can deliver the same power as multiple friction belts, reducing pulley sizes and space. In most cases, the reduced maintenance costs, reduced downtime and lower energy requirements should provide a payback in just 3-4 months. n Incorrectly installed and maintained belt drives accounts for around 98% of premature failures, resulting in lost production. Gary Price, regional group manager for power transmission products at Eriks, offers advice on how to extend the lives of belt drives and pulleys, increase their reliability, cut costs, and minimise downtime. Worn belts can be extremely costly in terms of downtime and lost production

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