Global bearing and rotating technology company SKF has provided a complete power transmission solution for a longstanding key customer, one of southern Africa’s foremost cement suppliers who had been experiencing problems with a bucket elevator over a protracted period.
The additives bucket elevator handles exceptionally abrasive and sticky materials such as natural and synthetic gypsum, limestone and slag. Frans Odendaal, SKF Product Manager, Power Transmission, explains that the machine already started giving problems in 2016 as a result of inappropriate chain selection for the particular application which was leading to costly unplanned downtime.
“At that time we conducted a survey and made a few recommendations based on the existing chain condition. A few months later, in April 2017, the customer decided to not only replace the existing chain but to simultaneously upgrade the bucket elevator. Due to our earlier involvement, the customer approached SKF alongside a number of their other suppliers for a reliable solution.”
In addition to the upgrading of the bucket elevator within the requested requirements, SKF also recommended further improvements to enhance efficiency and reduce downtime for the customer. “Shortly afterwards, we secured the order through our authorised distributor, Bearing House, in April 2018.”
The customer requested SKF to increase the capacity of the elevator from 60tph to 100 tph. Odendaal explains that this presented the challenge of accommodating the upgrade in the existing elevator casing while meeting a minimum safety factor of 14 for the chain.
“We consulted with our team in Singapore who suggested a chain design which we had previously used successfully in Vietnam. This particular design presented us with the perfect solution providing an even higher than required safety factor.”
After SKF did the necessary inspection of the bucket elevator, they proposed a full power transmission solution complete with modified sprockets and a new chain and buckets. SKF’s solution included a special pitch relief design on the sprockets for improved chain engagement, the use of segmented sprockets to facilitate replacement of teeth, hardened teeth for longer wear and life, and a stronger mounting design for the buckets.
SKF also introduced a few strategic changes in the mounting positions to eliminate some existing operating issues. To improve chain tension during operation, SKF modified the tensioning method. SKF’s Engineering Department was called on to supply complete shaft assemblies.
“In addition to meeting all our customer’s requirements, the use of improved material and the elimination of key ways using SKF locking elements enabled us to use the same shaft sizes under higher loads. Working within the current framework and avoiding structural changes delivered significant savings to the customer.”
Expected delivery of the 36m high bucket elevator, fitted with 180 buckets each weighing
approximately 14 kgs, at the end of September 2018 will be a milestone for SKF supplying its complete elevator chain solution in South Africa.
Odendaal confirms that SKF will be involved in the supervision of the elevator installation and that they will be responsible for performing regular ongoing inspections of the elevator chain. The cement company is a longstanding customer with SKF’s countrywide authorised distributors and has trusted SKF products and services for many years. “We are extremely satisfied with the successful outcome of this project as this is the first time that the customer is accepting our elevator chain over their traditionally preferred brands for this specific product and application triumph,” concludes Odendaal.
SKF is a leading global supplier of bearings, seals, mechatronics, lubrication systems, and services which include technical support, maintenance and reliability services, engineering consulting and training. SKF is represented in more than 130 countries and has around 17,000 distributor locations worldwide. Annual sales in 2017 were SEK 77 938 million and the number of employees was 45 678.