Specialised polymer manufacturer Vesconite Bearings has been supplying bushings made from the polymer Hitemp 150 for use in rock drills, significantly improving their wear life, and reducing their replacement intervals.

Hitemp 150 was developed about 20 years ago and is an internally lubricated bushing material with low friction designed to operate continuously in dry conditions of up to 150 ºC, and intermittently up to 170 ºC, and in wet or immersed conditions up to 120 ºC, Vesconite Bearings technical sales consultant Marius van Zyl explains.

“As such, the material is suitable for mining conditions, which are characterised by heat, water, dust and grime.”

The polymer bushings, with an outside diameter of 53.2 mm, an inside diameter of 42 mm and a length of 74 mm, are produced using injection moulding to reduce waste.

Van Zyl says, while Hitemp 150 applications are most successfully used in the sugar industry where it is valued for its ability to withstand high temperatures and high abrasive wear, the polymer has had success in the mining industry.

A global company specialising in pumping equipment has been manufacturing rock drills for the past ten years and continues to use Vesconite Bearings’ Hitemp 150 bushings in the rock drills. Vesconite Bearings has been supplying the bushings to the company for more than ten years.

Rock drills are designed to be robust because of the high impact, heat, dust and water exposure. Van Zyl says it is important that all components on a rock drill be robust too, since a failure of any component can lead to a lack of equipment availability and a higher cost per hour over the life of the machine.

“Therefore, careful attention needs to be paid to the rock drill bushings, since failure in this small component can have a tremendous influence on mining efficiency and productivity.”

Prior to the use of Hitemp 150 bushings, the bushings in the rock drills, in general, were replaced every two weeks, compared with the Hitemp 150 bushings only having to be replaced three to four times a year.

Product Demand
Van Zyl says the drilling and tunnelling sector is influenced by exploration activity, capital projects and production in the global mining industry. “With the uptick in many commodity prices, there seems to be a cautious optimism about mining globally that is likely to lead to investment in exploration and capital projects.”

Subsequently, this is likely to lead to an increase in activity in the drilling and tunnelling sector, and increases the demand for the bushings, in general, and Hitemp 150 bushings in particular, he says.