Robit is launching diamond button bits for top hammer drilling applications as it looks to increase the life and reduce the maintenance associated with these consumables.

The company plans to commence mass production and deliveries by the end of the year, but it has already signed up its first mining customer.

Traditionally, drill bits for top hammer drilling have been made of hard metal, but, while they may often prove effective when it comes to penetration in the initial stages, these bits can be worn down easily depending on the application.

The Robit Diamond Button Series bits have an industrial diamond coating that lasts many times longer than a regular bit and does not need to be sharpened, according to Robit’s R&D Engineer and Materials Specialist, Niko Ojala.

The diamond coating is applied to the buttons in much the same way as diamonds are created; namely by subjecting it to high pressure and heat, which makes it even more durable than natural diamonds.

Ojala said: “The coating has several layers, which ensures adherence and enables the diamond bit to withstand the shocks and heat fluctuations of top hammer drilling. Robit Group has previously used the diamond coating with success in oil and gas operations in softer substrates. Now the durability of diamond is offered for the first time for shock drilling in hard rock.”

Robit has been developing these buttons for five years, and field tests have been conducted extensively “with ever-improving results and great success”, Robit Sales Manager, Kimmo Kangas, said.

“Mass production and deliveries will begin during the latter part of the year; initially 89 mm and 102 mm diamond bits will be offered,” Kangas said, adding that Agnico Eagle’s Kittilä gold mine, in Finland, is to start using the Robit Diamond Button series later this year.

Agnico Eagle Kittilä Production Manager, Jari Kolehmainen and General Supervisor, Janne Saukko, remarked: “Test cooperation with Robit in these new innovative products has been productive. The goal is to use diamond bits to make remote drilling more efficient in terms of use of resources and productivity than drilling using regular bits.”

In test cases, the new diamond bits have yielded outstanding results, according to Ojala: “When drilling hard granite you may have to sharpen – ie change – a traditional hard metal button bit, for example, after 80 m, while with the diamond button bit you can drill nearly one kilometre.

“And, as the diamond buttons do not, in practice, wear out, then their penetrating ability does not deteriorate like regular hard metal buttons. Drilling speed, therefore, remains the same throughout the bit’s time of use. Similarly, the diameter of the borehole does not decrease as the bit ages, resulting in a more consistent and predictable end result in production drilling.”

He concluded: “The many times longer change interval of the bit saves time and is particularly important for remote-controlled drill rigs in fully automated mining environments where people are not present during the process.”