When it comes to pulleys, one size does not fit all. In fact, a one-size-fits-all approach will often result in equipment that is either too big or too small.
Cameron Portelli, Senior Mechanical Engineer at Kinder Australia, said everyone’s needs in heavy industry are different, with varying belt sizes and widths, shaft sizes and driveboxes.
“Custom pulleys are a large part of the industry. A one-size-fits-all approach can potentially result in unscheduled downtime or worse, a dangerous failure,’ he told Australian Bulk Handling Review.
“Kinder Australia provides specialised solutions that are engineered for purpose and built for maximum service life.”
Broadly speaking, Kinder designs specialised pulleys for heavy mining applications where material build-up on the pulley face causes mistracking and belt damage. As part of this process, Kinder engineers will visit the site to get as much information about the application as possible.
Using a mixture of information provided from the client and the site visit, the engineering team will provide a conveyor design report to accurately determine any tensions the pulley will be under.
Portelli said this involves looking at what they had in place previously, what was failing, and finding any discrepancies between the information the engineers were given and what was happening.
“One of the things our staff look for is site cleanliness,” he said. “Sometimes there can be a bearing failure due to ingress or contaminants, or spillage causing damage to other pulley components.”
“Generally, the head pulley is where most of the issues arise, as it’s the one operating under the highest forces. We look for signs of irregular wear or damage to the lagging and talk to the client to work out if there are spikes in throughput.”
Kinder has developed its own software that is constantly being built upon and informed by the Australian Standards. When it comes to pulleys, the business uses AS1403 to determine the factors and formulae to inform the pulley design.
In addition, the company’s engineers use finite element analysis, along with classical stress calculations to determine the stresses and deflections in conveyor pulley shells. Minimising stresses at critical locations around the pulley, such as the welded shell-end disc connection, is important to prevent fatigue cracking.
Each pulley undergoes static and dynamic balancing, with the welds fully stress-relieved and crack-tested with magnetic particle inspection and ultrasonic testing to ensure they will stand up to the pressures of their environments. Shafts are also ultrasonic tested after machining where required.
Portelli said the company’s engineers have a deep understanding of AS1403, which allows them to drill down into it and optimise the designs.
“We aim to achieve a design without being too conservative and increasing capital costs,” he said.
“Our software allows us to design pulleys for existing equipment and can adjust for specific parameters.
“A client might, for example, want a pulley of a certain size for which they’ve already selected or purchased a gearbox. We can then find a design that will work at the size of gearbox that is necessary and understand what materials will be needed for the stress factors.”
One trend the company has encountered is an increase in size. Systems that Kinder is being asked to provide quotes for have become bigger, with Portelli describing some as massive.
A bigger system can provide more throughput but will also often require larger equipment. One of the risks with this situation is the potential to lead to substantially higher capital costs – something Kinder aims to keep as low as possible.
While pulley lagging is a sacrificial wear face for the pulley, it must also perform as a traction surface at the drive pulley. Kinder ensures the correct lagging is selected to suit the system parameters and conveyor location, which goes a long way to ensuring drive traction over a suitably long wear life.
The company also manufactures specialised pulleys for difficult applications where material build-up can occur on the pulley face. The K-Conveyor Spiral Pulleys are designed to be used for dry and free-flowing materials. The rotation of the pulley engages the self-cleaning action, thereby releasing foreign material through and on to the inner tapered cone then to the outside of the conveyor.
K-Conveyor Wing Pulleys can be used for large lump, sharp and sticky materials and are designed to be used in adverse, abrasive and dirty applications, especially where there is material build-up on a solid conveyor pulley shell.
K-Conveyor HD Wing Pulleys are designed for applications where the standard wing design maybe inadequate for the duty.
All of these specialised pulleys are sensitive to high-load and high belt speeds, which is why Kinder recommends consulting with one of its field applications engineering specialists to find the right design.
Portelli said Kinder now plans to further explore AS1403 to find out if any improvements can be made.
“We’re partners with a university and want to work further to find out what in the standard is too conservative,” he said.
“There is a great opportunity to really drill down into the standard and find ways of making our designs more optimal for customers.”