Aggregates Manager

January 2018

Aggregates Manager Digital Magazine

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30 AGGREGATES MANAGER / January 2018 EQUIPMENT MANAGEMENT check for potential mistracking. Manual adjustments to the idlers are frequently needed. On the occasions that problems are not caught in time, belts can be damaged. By installing automatic return training idlers in varying intervals, alignment issues can be eliminated, freeing up maintenance time for key efficiency gains. When choosing a belt trainer, make sure that the return trainer is indeed automatic. If a trainer is not automatic, it requires frequent adjustments — and that really defeats the purpose. Also, depending on the brand one chooses, the return training idler is either a contact or contact-free product. Much of the industry prefers a return trainer that is contact free, as this elimi- nates wear parts and any side contact to the belt. So, a contact-free trainer leads to longer wear life and less mainte- nance. Additionally, look for models featuring rubber lagging which sheds material and increases friction, keep- ing the belt aligned. Note that certain trainers operate by using the gravity of the belt weight. Using the weight of the belt to make the roller shift (and thus track the belt) is the optimum method. The misaligned belt puts pressure on one side of the training idler, and this pressure causes the training idler to tilt and guide the belt back to center. Avoid oversizing When specifying a system, bigger isn't necessarily better. A common miscon- ception is that oversized equipment lasts longer and requires less maintenance. Conveyors should be sized according to the expected load, yet allowing for a small capacity increase. For example, specifying a larger belt than what is truly required will ultimately result in additional belt and idler rolling resis- tance and less energy efficiency. Use correctly-sized, efficient motors Manufacturers typically install new premium efficiency motors on overland systems. Since these motors perform most efficiently near their designed power rating, it's recommended to run at between 75 percent and near 100 percent of full-load rating. Alternatively, when a system is running at 50 percent of capacity or lower, the efficiency of the motor drops dramatically. Motor size should be matched to the horsepower requirements of the load. Again, some producers may oversize a motor thinking that it will require less maintenance; however, the energy savings realized from a properly-sized motor will outper- form any maintenance savings derived from a larger model — especially in regions where energy costs are high. Monitor and minimize rolling resistance Pay close attention to various features and benefits when specifying belts and idlers. For example, manufacturers are now designing belts with special covers that help to counter rolling resistance. As to idlers, they all may seem alike, but they vary in performance. Ask your conveyor manufacturer to recommend the right bearing and seal type for your application. Proper idler spacing is also important, as it affects both the shape and support of the conveyor belt. Consult with the Conveyor Equipment Manufacturers Association (CEMA) or your conveyor manufacturer for idler spacing and rolling resistance formulas. Maintain preventive maintenance Bottom line: the efficiency of the overland system is only as good as one's preven- tive maintenance program. As to motors, regular lubrication and cleaning helps minimize loss from friction and heat and extends motor life. Also, systems must be periodically checked for improper belt tensioning, belt slippage, non-rolling idlers, and material carryback. Each of these issues affects energy efficiency, while resulting in costly downtime and excessive wear and tear on overland systems and components. AM V-shaped wing pulleys deflect material away from the pulley and belt, minimizing the potential of pulley or belt damage. Overland system capacities vary from a trickle all the way up to 30,000 tons per hour. Alan Schmidgall is vice president of customer service for Superior Industries.

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