Tungsten Carbide Buttons Used for DTH Drill – Failure Mode (1/2)

Although tungsten carbide buttons have higher hardness and impacting resistance, it is brittle and has poor wear resistance. In the process of drilling, the high temperature of the high-speed collision with rock buttons occurrence arising will make carbide hardness decreased and crushed quartz particles made of a soft but opposed the hard phase transition occurs. Therefore, tungsten carbide buttons used for DTH drill failure will directly affect the drilling efficiency. The failure mode of tungsten carbide buttons used for DTH drill includes wear (grain wear, surface fatigue wear and adhesive wear), buttons break, buttons drop and so on. Next, we will discuss these failure modes one by one.

1. Wear: This is the commonest failure mode of tungsten carbide buttons used for DTH drill, which can be specifically divided into grain wear, surface fatigue wear and adhesive wear. Due to the conditions of DTH drill is usually strict, such as underground, down hole operation. The DTH drill buttons except impact and rotary crushing rock and rock cutting wear occurs, the air flow generated by the drill cuttings will be written to the buttons wear, especially in some high pressure DTH drill bit. DTH drill carbide buttons can be divided from the inside edge of middle and edge button, the middle button is mainly used for crushing rock, while the edge button not only involved in rock crushing,  but also plays an important role is to protect the drill bit to prevent the surrounding rock drill bit itself wear. Since DTH bits during the rotary cutting rock edge against the outer edge of the button so large line speed, it will be wore earlier so that the size of the edge is larger than the middle ones, but the speed of wearing is higher than the middle.

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