Retract button bit is a top hammer drill bit featured with a retrac skirt. Different with standard button bit, When the drill bit is stuck or buried, the retrac button bit can help to quickly remove the bit, greatly reducing the risk of losing the bit, while improving the straightness of the borehole and the efficiency of slag removal.
But how to select the right retrac button bits for drillers?
Step 1. Check the rock formation to decide the shape of bit skirt. If the rock is fractured, loose or easy to collapse, Retrac skirt button bit should be the first choice. If the rock is hard - very hard, standard button bit should be selected.
Step 2. Decide the shape of tungsten carbide teeth and face design. Ballistic and spherical teeth are the most common teeth shape in button bits. Hard rock like limestone, granite, basalt and quartzite and complete rock formation is suitable for spherical tungsten carbide teeth. Contrarily, ballistic teeth features of low compact resistance, easy bent and deformation. Herein, it better suits for soft-medium hard rock.
Step 3. Decide the bit diameter based on hole size. First, determine the nominal diameter of the retrac button bit according to the designed borehole diameter. Then, make minor adjustments based on the degree of rock fragmentation, drill rod thickness, drilling rig capacity, and slag removal conditions. Prioritize the use of easily reversible button bits with industry standard diameters( 45mm,51mm,64mm,70mm,76mm,89mm,102mm and etc ).
Step 4. Decide the thread. As long as we determine the thread of rock drill, shank adapter, or drill rod, we could know the thread of bits. If the thread of these three components are not same, it will cause the lose of compact transmission, bit stuck, bit loose or drill rod lost. Generally speaking, the bigger of the rock drill power, the bigger of the thread, and the bigger of the button bits.
Step 5. Bit material is important. The tungsten carbide material is different with skirt material. The better the material is, the harder it can withstand the rock. Cheap material may decrease the efficiency of drilling.
