SLASHING COST OF DOWN-TIME AND MAINTENANCE ON LOW PROFILE CONVEYORS
A recent article in a major periodical discusses the merits of “Proactive Maintenance”. Some suggest that Proactive Maintenance can yield more than a ten-fold savings over contemporary predictive / preventive programs.
While predictive and preventive maintenance attempt to regulate symptoms before breakdown, the intent of Proactive Maintenance is to reduce or eliminate the basic causes.
To be effective, Proactive Maintenance must begin at the evaluation stage. Until we understand, and accept the cause of our problems, we cannot expect to reduce or eliminate them. The following evaluations are based on over twenty-five years of Low-Profile Conveyor association, and are intended to reveal the root cause of common problems found in various Low-Profile Conveyors. Reviewing service manuals can also be helpful, unlike advertising, they tend to reveal the products true nature. Low Profile Conveyors as discussed here-in, are considered as utilizing pulleys 1.0” to 2.0” in diameter, with high tensile polyurethane belting, and limited to 24” maximum width.
Pulleys in the lower size range will normally reduce belt fatigue life. Average belt fatigue life on a conveyor with 1.3” diameter pulleys will never equal that of a conveyor with 2” diameter pulleys using the same belt. This is because the belt surface stress on the 1.3” pulley is approximately 56% greater than that of the 2” pulley. This reduced stress of the 2” pulley also allows using a heavier more durable belt that could not be applied to the 1.3” pulley.
Utilizing UNCROWNED pulleys with a small vee-guide to control tracking, is not recommended by many belting sources due to vee-guide wear, and can lead to reduced life of a more costly belt. The majority of all belting sources normally recommend crowning as the first choice for controlling belt tracking. Use of properly applied vee-guides should be in conjunction with crowned pulleys.
Pulleys with sharp knurling to offset low tension can reduce belt life due to the abrasive action of the knurl. Abrasion residue build up in the knurl may cause belt slippage, and miss-tracking, resulting in unexpected down-time. The pulley knurl can eventually also become worn by this abrasion and require replacement.
Bearings are the heart of the conveyor, however, they can also be the number one problem area. Small bearings with insufficient capacity can encounter greatly reduced life if merely subjected to increased loads caused by added belt tension. Bearings lacking a self-aligning feature can be subjected to over-stressing induced by drive pulley deflection, and miss-alignment. Small pulley diameters also accelerate bearing failure, a 1.3” pulley utilizing identical bearings and belting conditions as a 2” pulley, would have an average bearing life only 65% of the 2” pulley. This is because the 2” pulley runs at a much lower R.P.M. to produce the same belt speed. Drives utilizing a flexible coupling to connect the reducer output to the pulley can also induce additional pulsating bearing loads to both the reducer and pulley bearings. This not only increases bearing wear, but also necessitates maintenance on the coupling. Utilizing the pulley shaft as the bearing inner race should be avoided. If the shaft is not made of bearing quality steel, and properly heat treated it can become the weak link in the bearing system. Failure normally requires replacement of not only the bearings, but also a more costly pulley or shaft. This construction also exposes these multiple bearing elements to contamination during storage, assembly, and replacement.
Due to these numerous bearing deficiencies, many major conveyor producers exempt bearings, and reducers from their warranty.
A major disregard for these maintenance problems and the labor involved is costing industry millions each year. The simple function of increasing belt tension and retracking can require an 833% increase in procedures by one producer over that of another. Belt changing on stand mounted conveyors can be accomplished forty times faster by one producer than others. This same producer can exchange a complete drive in the same time ratio. Modern sealed for life bearing and drive technology can totally eliminate all relubrication and its related contamination.
Allow your company to eliminate this costly waste, and begin your “PROACTIVE MAINTENANCE PROGRAM” Light-Years ahead, by eliminating all of the aforementioned negative aspects. Selection of a product for a non-essential reason merely to save a few dollars is rarely a valid reason if it may cost you or your customer thousands in lost production, and maintenance.