What started out as a simple bearing selection turned into a complete shaft redesign, manufacture and assembly for a local small-sized mill OEM customer.
When the customer, who owns the proprietary design for a new small-sized material processing mill concept, was experiencing premature bearing failure, contamination ingress and catastrophic failure on their jaw couplings, they approached bearing and rotating specialist, SKF, for a solution.
The design of the compact, multi-shaft, vertical mill which has the capability of processing various materials, features a few horizontal shafts with strengthened flinger attachments that agitate the product as it passes through the mill. The milling action combines several processes such as crushing, milling, densifying, blending and attrition to provide an output product that will coincide with various specifications within a variety of applications in sectors such as mining, energy, steel manufacture, waste reprocessing, environmental rehabilitation, agriculture as well as general milling.
The SKF Project Engineering team donned its collective thinking cap to find the best solution for the customer. “We proposed a complete redesign of the entire shaft assembly which includes bearing selection, improved seals as well as a new housing design,” explains SKF Application Engineer, Cody Petersen.
The new shaft assembly incorporates SKF’s superior, case-hardened spherical roller bearings. “We selected these particular bearings given their design which is highly suited for high vibration and shock loading applications,” notes Cody. “The locally manufactured shaft and housings were machined, and quality controlled by SKF to ensure that our bearings reach their intended lifespan.”
The improved sealing solution included the addition of an internal double lip seal and an improved labyrinth seal design incorporating a special cup and O-ring system that provides dynamic sealing against contaminant ingress and prevents lubricant loss.
The complete scope of work by SKF on a total of ten shafts, including one spare, comprised of 22 bearings, 22 rotating and 22 stationary labyrinth seals, 11 clamping rings, 33 radial shaft seals and 10 non-drive end and 10 drive end housings.
“We also proposed a complete SKF grid coupling due to the fact that it is more forgiving and better suited to the milling speed than the existing couplings that were on the shafts,” Cody concludes.