Bit selection should be evaluated based on three key aspects: formation characteristics, required hole depth, hole diameter. General recommendations:

• Extremely hard formations: Use large-diameter domed button bits, preferably with double-row button configuration
• Very hard formations: Use domed button bits with a flat face design.
• Medium to hard formations with uniform rock layers: Use domed button bits with a concave face design.
• Medium to soft formations: Use edge domed buttons combined with center sharp or fully pointed buttons, preferably with a convex face design.

An oversized drill bit refers to a drill bit whose diameter or design exceeds the standard specifications or recommended operating limits for a given DTH hammer. Such bits fall outside our standard quality warranty scope. We generally classify oversized drill bits into the following two categories:

• Customer-specified special-purpose bits: When a drill bit is customized for an unclear application or highly specific operating conditions, it is manufactured strictly in accordance with the customer''s drawings, material specifications, and process requirements. In such cases, no performance or service-life guarantees can be provided.
• Excessive bit diameter: Drill bits with excessive diameters significantly increase the torque load at the connection between the bit and the hammer. This may exceed the structural limits of the bit shank, potentially leading to bit body cracking, fracture, or other unpredictable failures.

Carbide button breakage alone is not covered under the standard warranty. Carbide buttons are extremely hard and are designed to crush hard rock under normal drilling conditions without fracturing. However, button breakage may occur when the carbide impacts materials of similar or higher hardness, such as alloy steel objects left in the hole. Before drilling, ensure that no alloy steel debris or foreign metal objects are present in the target drilling area. During drilling, carbide button breakage may be indicated by abnormal impact noise. If such noise is detected, drilling should be stopped immediately and the hole bottom cleaned to prevent secondary damage to other buttons.