Young SA innovations company, Black Knight Technologies, used the latest design technology to facilitate the design and documentation of its newest invention - a rock crusher that could make a major impact on rock-crushing performances at local gold mines, and in other applications.

The key to the rotary offset crusher (ROC), designed by South African engineers Michael Hunt, Henry Simonsen and Ian Sinclair, is the high speed of operation, provided by two high-speed rotating discs at the core of the invention. It can achieve crushing ratios (the ratio of input size to output size) in excess of 20:1. Traditional methods - jaw, cone and gyratory crushers - typically achieve ratios of 7:1.

The machine - a 100% South African invention - recently received a prestigious SABS design award. Singled out also for a special sponsor's award for world-class design, the crusher could also be used in a wide range of other applications including the building and construction industry, cement industry, coal-fired power stations as well as the food industry.

Rock particles, driven by high centrifugal acceleration, pass through the ROC at very high speeds. The crushing process, which occurs between two discs, has an equally high cyclic frequency - so the faster the machine runs, the greater the throughput of material. The small footprint of the South African-designed ROC makes it ideal for underground use. Its uncomplicated design also means low capital and maintenance costs.

Hunt says Black Knight Technologies is excited about the speeds and results achieved with the prototype. "We have also designed and installed a pair of special discs to test the possibility of using the same machine for milling down to micron-sized particles. The results have shown us it is possible," says Hunt.

Black Knight Technologies are continuing with their development work on the crusher and are currently investigating ways of introducing the machine into the market as soon as possible.

Model-based design technology of Autodesk Inventor played an integral role in the development of the ROC. Hunt says the design technology, tailored specifically for the manufacturing environment, enabled him to quickly and easily assemble a 3D model of the ROC. "3D modelling has come a long way in the past five years. Today, it is efficient and easy to use.

"The ease with which I could work on Autodesk Inventor, meant I could put all my energy into coming up with an efficient design. I did not have to waste any time on creating detailed drawings. The system did all that for me in a few minutes," says Hunt, who only became involved with digital design late in life. "It was 15 years ago, when I retired as chief director from the CSIR and set up my own design consultancy, that I started using computer-aided design (CAD)."

Hunt says the power of digital design has slashed the size of design teams. "If I had worked on the design of the ROC 30 years ago, I would probably have been part of a 10-member design team."

For more information contact Autodesk, 012 664 8115.