Split roller bearings (SRB) have saved millions of Rand in downtime for South African company, Xstrata Alloys, one of the leading producer of ferrochrome and primary vanadium. Using SRB, Revolvo’s South African agent, OE Bearings, was able to temporarily fix a shaft, enabling Xstrata Alloys to avoid lost revenue by remaining operational for a whole month while a new shaft was manufactured. Xstrata approached OE Bearings after discovering that one of their shafts, which fed raw materials into a kiln, was damaged. The company was facing downtime costs of approximately 90,000 Euros per day.
“With the machine in this condition Xstrata was probably looking at a few million Rand’s worth of downtime costs,” said Warwick Steinhobel, a director of OE bearings. “That was the problem we were facing when we were called out to do some urgent repairs. When we investigated the shaft, we realised that we would have to engineer a temporary solution so that downtime could be averted while a new shaft could be built.”
“The shaft was badly worn, and on a detailed investigation, it was discovered that the shafting was undersized by 20mm.This was a major problem; in this type of business 50 microns is the maximum that should be encountered. The challenge we were facing was that replacement of the shaft would have taken at least four- days,” said Steinhobel, “We decided we would build a platform for the bearing next to the existing shaft, moving the existing bearing off the damaged shaft. We then placed shims between the bearing inner race and the shaft - and installed the bearing on the modified shaft.”
But to do this, the OE Bearings team had to work an entire day, right through the night - and into the next day. The temporary solution involved the use of specialised SRB split roller bearings. These offered a host of advantages from the technical, economic and pure design point of views, The bearings were simple to fit; a major factor in their longevity; they provided a longer life span because they could not be cross-located; and they also provide superior sealing arrangements, delivering longer bearing life with greatly reduced levels of maintenance.
“The fact that the SRB split bearings only take about 1 hour to fit, as opposed to solid bearings which take 8 hours, is a major factor when you are dealing with downtime costs that can reach 45,000 Euros“, said Steinhobel.
“Fast change-out is essential and the SRB split bearings are much more efficient in this area in ensuring maximised plant up-time.”
Commenting upon the Xstrata application, Adrian Menzies, Sales & Marketing Director for Revolvo, said that: “The cornerstone of our specialised SRB service is our willing¬ness to work closely with equipment manufacturers and end-users like Xstrata to solve specific application problems. This has led to the development of a number of innovative designs, such as thin section, high speed bearings for wire stranding machines, and highly robust and reliable water cooled units for continuous casting applications in the steel industry. Some of these specialised designs have subsequently been incorporated into the standard SRB product range.”
The final word belongs to Nkosana Maseko, engineering superintendent, SRC plant, at Xstrata; “It wasn’t just their ingenuity that impressed us, it was the speed at which they worked,” he said. “One seldom encounters this level of service and expertise. The bottom- line is that we were able to save a lot of money.”
