The first batch of 60 Magnevane pneumatic chainsaws (The Swordfish M15) with Vesconite Hilube polymer vanes has arrived in South Africa in early March 2021.
The air motor. Photo by VesconiteA further 150 saws will arrive monthly thereafter to go into the South African underground gold and platinum mines, which get through 15 000 pneumatic chainsaws every year. The Magnevane Swordfish has the most powerful and efficient air motor in the world, which is one of the reasons it uses Vesconite high performance polymers.
The pneumatic chainsaws were developed for underground mines in which timber poles are often used to support the roof – known as the hanging wall – to prevent collapses in the confined underground stopes (work areas) that follow the orebody.
Tested on several South African gold and platinum mines, the Swordfish demonstrates better performance than traditional chainsaws. The chainsaws cut support poles in restricted spaces and are required to have excellent reliability and efficiency so they can remain underground for extended periods.
The Magnevane Swordfish is distinct from its competitors in several ways, including its ground-breaking patented air motor that uses magnets to maintain an airtight seal between the vanes and the motor housing. Magnevane has chosen to fit its chainsaw motor with Vesconite Hilube self-lubricated wear-resistant vanes, which provide both longer vane life and lower friction to further enhance the high-performance characteristics of the Magnevane air motor.
Standard air motors use a few different techniques to create the seal between the vanes and the housing. Some air motors have springs to push the vanes against the housing. However, because of the rapid temperature changes the springs lose tension over time and do not last long, so increasing maintenance cost and downtime. Another option for high-end motors are cams that push out the vanes at intervals, but this too has disadvantages in that they limit the range of motion available and are more expensive to maintain. Further options include air channelled through the shaft pushing out the vanes, or simply centrifugal force. All of these options have severe limitations and result in declining performance over the life of the vane, which needs to be compensated by over specifying the motor.
The patented Magnevane design overcomes all of these constraints by using high-powered neodymium magnets in the core and vanes of the motor to ensure 100% sealing from the first RPM and throughout the life of the vane.
“The differentiator in the design is four specially made neodymium rare-earth magnets installed on each of the seven Vesconite Hilube vanes as well as more stacked and cone-shaped magnets installed in the core rotor. These hold the vanes against the housing all the time and torque is obtained from the first spin for the whole life of the vane – a very rare and significant achievement and completely changes the operating profile of Magnevane motors,” says Magnevane CEO Gareth Rees.
With this design, the company has achieved a 50% to 60% increase in efficiency against the current leading air motors in the market. In addition, since the vanes are always pressed against the housing and Vesconite Hilube is a superior product, the company is achieving a 300% longer maintenance life cycle, with consistent performance attained over this time.
Rees reports that the company investigated bonded vanes but, since these wear out quickly, they reduced the life of the motor by 50% to 70% and Magnevane concluded that Vesconite Hilube is the best performing vane material that it has tried to date. By fitting Vesconite Hilube vanes, the company has two benefits: the motor runs longer with a better wear life and the efficiency of the motor is increased.
Magnevane’s first tooling application to use their patented motors, the chainsaw, has been in development and testing for several years, and has already proved itself in the harsh South African mining environment and is now ready to be introduced to other mining countries, with Portuguese-owned Magnevane expecting to obtain a significant share of the 15 000 unit underground South African chainsaw market within three years.
The company is also developing more end-to-end applications, such as displacement pumps and compressors. Magnevane continues to work with Vesconite Bearings on these applications, including the Hitemp160 polymer that is heat resistant to 160ºC and is a prime candidate for the vane material of the Magnevane displacement pumps.
Besides manufacturing products, the Magnevane sees itself as a research and development company with intellectual property, including its air motors with magnets, which it is prepared to licence to original equipment manufacturers.
“This is the best air motor in the world – with the best vanes,” enthuses Rees, “and will move the dial on pneumatic operating costs across industry.”
