Button Bit Sharpening

Step 1

Hard rock drill bits have Tungsten carbide “buttons” that become dull and flat during the drilling process. These buttons can be refurbished to extend the service life of the drill bit.

Step 2
To enable the correct grinding of the button, the surrounding steel body must first be removed. The traditional method is to grind the steel using an Angle Grinder. This method is labour intensive, creating health hazards ranging from muscle strains to respiratory problems not to mention the environmental issues from the grinding dust and noise.

Step 3
The alternative technique for this is a system that utilises reverse electrolysis in a salt water solution to erode the steel, without affecting the Tungsten carbide. Drill bits are suspended above a copper cathode plate with enough salt solution to cover the area to be eroded. Low voltage current is then transmitted between the cathode and the bit body, thus eroding the steel.

Step 4
An 89mm diameter drill bit can have approx. 1.5mm of steel removed in 15 minutes. The tank accommodates six drill bits of this size per cycle. Each cycle is controlled by an in-built timer, which allows other work to be completed during the erosion process.

Step 5
To restore the Tungsten Carbide button back to “as new” condition, a Swedish made bit sharpening machine is used. This semi-auto machine utilises diamond impregnated grinding pins that have a concave shape that matches the style and size of the button. A recirculating coolant system suppresses any dust whilst cooling the carbide and grinding pin.

Step 6
The whole process can be repeated 5-6 times for each drill bit, which equates to significant cost savings for our customers.

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