Rock Drill Bit Specifications Explained: R32, T38, T45, T51, ST58 and ST68 Series for Rock Drilling

Rock Drill Bit Specifications Explained: R32, T38, T45, T51, ST58 and ST68 Series

Selecting the right rock drill bit specification is essential for productive and safe rock drilling operations. In this article, Brighttop Global Co., Ltd. explains the common rock drill bit series used in the industry, their applications, and the key considerations that help drilling teams avoid costly mismatches.

Common Specifications and Their Applications

• R32 Series: Drill bit diameters ranging from 32–51mm are well suited for medium and small-scale rigs, tunnel excavation, anchor holes and medium-hard rocks. This specification offers a strong cost-performance ratio, making it a widely consumed series in the industry.
• T38/T45 Series: These drill bits, with diameters of 54–89mm (T38) and 76–102mm (T45), are designed for larger rigs and play a key role in main blast holes for tunnels, as well as for medium to hard rocks. They offer higher bending strength, ensuring durability under demanding conditions.
• T51/ST58/ST68 Series: Suitable for drill bit diameters exceeding 89mm, these designs are engineered for deep hole operations in large rock drilling rigs dealing with extremely hard rock layers. The use of a shouldered connection helps prevent thread shearing damage.

Critical Application Considerations

Avoiding Mismatched Configurations

It is important never to combine “small rod with large bit” or “large rod with small bit.” A precise thread fit is essential to prevent energy loss, borehole deviation and potential safety hazards. Always verify the internal thread cleanliness and chamfer of new drill bits before operation.

The Advantages of Passivation Treatment

Passivated spherical tooth drill bits exhibit a longer service life, averaging 5–6 times longer than standard blade-head bits. This enhancement is particularly beneficial for mechanized continuous operations, minimizing the frequency of bit replacements and supporting steady project progress.

Conclusion

In the expansive field of rock drilling, understanding the relationship between rock drill bits, threading specifications, diameters and tooth configurations is essential. Whether your project involves tunnel excavation, quarry blasting or underground mining, the correct combination of thread specification, drill bit diameter and tooth configuration directly influences penetration rate, service life and operating cost. Consulting with the supplier’s technical team before purchase helps confirm that the selected rock drill bit series matches both the rig’s thread system and the rock conditions at the job site. For professional-grade rock drill bits, working with a trusted manufacturer and factory specializing in rock drilling tools is a valuable step toward completing projects safely and effectively. Brighttop Global Co., Ltd. provides a wide range of rock drill bits and related drilling tools for tunneling, mining and construction applications. For more information or to place an order, email Brighttop Global Co., Ltd. at contact@csrockdrilling.com.