When a global company that specializes in pumping equipment developed a rock drill, trials with other products led to it specifying bushings made from the temperature-resistant, internally lubricated, wear-resistant polymer, Hitemp 150.
Whereas the bushings were replaced every two weeks prior to the use of Hitemp 150, the use of the polymer reduced the amount of bushing replacement to 3 to 4 times a year in an environment in which the continuous exposure to high temperatures, water and pressures results in significant stress on the bushings.
Orders for Hitemp 150 bushings for this application have been steady since 2007 owing to its 150ºC temperature rating as well as its high abrasive wear resistance.
Some 4200 rock-drill bushings were produced late last year and, what was unusual about this batch of bushings was that, rather than its traditional brown Hitemp 150 colour, the identical-chemical-formula bushings will be black, as a result of the lack of availability of raw materials of the standard colours.
The polymer bushings, with an outside diameter of 53,2mm, an inside diameter of 42mm and a length of 74mm, are produced using injection moulding so as to reduce waste.
These bushings are then final machined to remove the excess material, known as the sprue.