SKF South Africa has recently developed and delivered a complete and cost-effective bearing and housing solution for a ball mill destined for a mine site in North-West Africa.
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An SKF customer specialising in grinding mills and comminution processes has, over the past years, employed several SKF product and service solutions, including bearings and housing assemblies for mill pinion applications.
The holistic solution from SKF consists of spherical roller bearings (23292 CAK/C3W33), locally designed and manufactured custom housings (CSD 231-500), adapter sleeves, an oil taconite sealing arrangement, as well as locally manufactured adapter sleeves (OH 3292 H). The customer also called for a life calculation on a specific pinion design.
According to SKF Application Engineering Manager, Janus Bezuidenhout, the 23292 CAK/C3W33 spherical roller bearing was selected as the best possible bearing, based on the pinion criteria received from the customer. SKF assisted with the bearing selection via various SKF software programs.
The local bearing housing, which was selected based on past successful projects with a similar footprint, is based on the South African designed SDJD-type housing. As this housing is specially prepared for circulating oil lubrication, it is perfectly suited for the 23292 CAK/C3W33 bearing. Bezuidenhout explains that these specifically designed housings are customised for the customer as well as for the application. “The customer required a housing that was durable during heavy loaded applications, while at the same time custom-designed to ensure that it fitted the end-user’s structure: by taking into account the specific pinion centre height, for example. Moreover, the material we selected is suitable for occasional high vibrations, temperature differences and loading specifications.
“The added value offered by these particular bearings and housings is that they have good lead times in terms of availability, ensuring on time delivery of the project in accordance with the customer’s requirements,” says Bezuidenhout.
He also draws attention to the units’ price competitiveness. “Local manufacture eliminates the need for import and associated costs around exchange rates, enabling us to remain within the customer’s budget.
“Another benefit of this particular type of housing design is that SKF can modify the sealing arrangements and housing bore to suit the required bearings and seals,” adds Bezuidenhout. “The locally designed and manufactured oil taconite sealing arrangement we used has been implemented in the industry for many years and is custom for large size bearings operating with circulating oil lubrication.”
The seal consists of a static ring that is mounted onto the housing; a flinger, clamping and spacer ring used to secure all the components on the shaft, and matches the static ring; and a V-ring that is incorporated with a grease port in the static ring. The V-ring prevents contamination from entering externally into the bearing, and the grease port is used to purge the contaminates out of the sealing arrangement. O-rings are incorporated to seal the arrangement on the shaft and prevent contamination from entering the bearing.
Bearing maintenance is facilitated by the adapter sleeves, which make mounting and dismounting of the taper bore bearings on parallel bore shafts easy. Bezuidenhout explains that the taper of the sleeve corresponds to the taper of the bearing and there are oil injection ports for the mounting and dismounting procedures. The locking nut and clip for locking the bearing in place is inclusive of the sleeve.
“SKF’s involvement in the complete supply chain solution, from procurement to delivery, put us in control of the entire process, enabling us to mitigate any potential risks around the project,” states Bezuidenhout.
SKF delivered all the components in March 2023 to the customer’s storage yard within the required lead time. From there they were transported via sea freight to the final end-user in North-West Africa. “The success of the project prompted the same customer to ask us to replicate the solution for another project in West Africa, which we again delivered on time in April 2023,” concludes Bezuidenhout.
