Often when reviewing low profile conveyor literature I am confronted with tantalizing statements such as, “OUR CONVEYORS ARE BUILT TO LAST” “OUR PRODUCTS ARE BASED ON THE VOICE OF OUR CUSTOMER” “CUTTING EDGE TECHNOLOGY” “FASTEST BELT CHANGE ON THE MARKET” “DESIGNED TO VIRTUALLY ELIMINATE MAINTENANCE”. After reading this, one might assume that these companies have obtained perfection.
Why then would a conveyor manufacturer continue using needle bearings to support a drive pulley, when they should realize the limitation of these bearings? Instead they recommend keeping replacements on hand, and exempt bearings from their warranty. Needle bearings have no self-aligning feature to prevent non-uniform loading, nor do they have any practical axial load capacity. They have a minimal lubrication capacity and on average, require twice the lubrication frequency of ball bearings. Even if lubrication were not a factor, this application could result in a reduced bearing life due to excessive needle loading, induced by pulley miss-alignment, deflection, and creep. Because this is not a self contained sealed bearing element it can be subject to contamination during assembly and maintenance. Integrity of the bearing inner race (pulley) may also present a problem since it is not a product of the bearing manufacturer. This doesn’t appear to be CUTTING EDGE TECHNOLOGY.
This same manufacturer actually utilizes self-aligning ball bearings (which are well suited for this application), on their more expensive units. Another major low profile conveyor manufacturer, who suffered through five years with needle bearings, has long since adopted the ball bearing.
WHY would this manufacturer claiming “THEIR PRODUCT IS BUILT TO LAST” not use a totally self-contained sealed bearing unit? Using the pulley shaft as a wearing bearing element can be expensive for the end user. Bearing failure may require replacement of not only the bearings, but also the more expensive pulley which acts as the bearing inner race. Not replacing the pulley means the new bearings may be installed on a worn inner race, which can have a negative effect on their life.
WHY do these conveyor manufacturers utilize pulley diameters close to the minimum recommended for much of the belting used, when it has a negative effect on belt, and cleat fatigue life, and a drastic effect on bearing life? Is this really “THE VOICE OF THEIR CUSTOMER”?
WHY would a conveyor manufacturer’s “CUTTING EDGE TECHNOLOGY” require re-lubrication of bearings, and oil changes on gear reducers when sealed for life bearings, and reducers have, on average, demonstrated improved life over these out dated systems for years?
WHY would a conveyor manufacturer claiming their product is “DESIGNED TO ELIMINATE MAINTENANCE”, equip their pulleys with a sharp diamond knurl when it is well known this can cause belt abrasion, and is not recommended by most belting manufacturers? They then reveal in their service manual that residue can build up on the knurl causing miss-tracking and belt slippage, and recommend cleaning the knurl, (which requires removing the belt or pulley). They also suggest if the knurl is worn, the pulley should be replaced to avoid belt slippage. Then, depending on the age of the conveyor, new bearings, and bearing plates, may be required. This company also advocates stocking complete drive and idler kits.
WHY would a conveyor manufacturer utilize a small conveyor resting on a bench or installed in a non-functioning position in a demonstration fixture, not encumbered with being bolted to stands or a machine base, and free from any obstructing side rails, or functioning drive, and then claim a one to five minute belt change? Do they really think their customers, who take up to 60 to 90 minutes to change a belt on their real world conveyor installation, are going to accept this statement of “FASTEST BELT CHANGE ON THE MARKET”?
WHY would anyone not offer a “crowned pulley” which is recommend by all belting producers, and provides an automatic wear resistant tracking system? The use of only a bottom vee guide which adds a major wear point to the belt, and offers no non-contact corrective action, can result in reduced life of a more expensive belt. Does this really ELIMINATE MAINTENANCE?
WHY are all these items which have such a negative effect on performance, reliability and cost, being camouflaged with these tantalizing statements?
The December 2006 issue of a Popular Publication contained an article relating to “IMPLIED QUALITY” that offers a possible explanation for this camouflage. The author states that many Companies put more effort into creating an “IMAGE” of quality, rather than trying to achieve this quality. He goes on to say that sadly, this makes sense because saying you have “HIGH – QUALITY” is easier, and cheaper than actually achieving this “IMPLIED QUALITY”. Maybe now we have one answer to “WHY.”