What Is a Hydraulically Guide Rod?

Table of Contents

Hydraulic guide rods, as a drilling tool for modern engineering, have become an indispensable part of industries such as mining, geological exploration, and construction with their unique design. In complex drilling environments, hydraulic guide rods can improve the straightness of drill holes and achieve efficient and accurate drilling operations. Therefore, many engineers and technicians need to understand and master the relevant knowledge of hydraulic guide rods. This article will explore the basic concepts of hydraulic guide rods to help you better understand this critical tool.

Application and characteristics of hydraulic guide rods

guide rod

Hydraulic guide rods are mainly used for deep hole drilling in underground mining and open-pit mining and drilling in severe rock fissures to ensure the straightness of the drill hole. The guide rods are usually employed in the first position of the coupling with the drill bit.

In addition to being used in the first position of the rod set, guide rods are also used in the combination of all guide rods in large borehole and deep hole drilling, and the rod connection is usually of the shoulder-punching type. The outer diameter of the rod is a whole straight cylindrical structure, and the two ends are quick-change coupling with the female and male threads. The difference between the outer diameter of the rod and the diameter of the drill hole is usually more than 12mm, and there are two types of bottom punch and shoulder punch according to the contact part of the impact surface. The guide rod’s outer diameter, bore, and thread structure are comparable with the ordinary thread of the MF rod. Shoulder-flush type guide rods increase the load-bearing positioning surface at the thread.

MF rod

Structure and process design of hydraulic guide rod

The outer diameter of the guide rod is an integral straight cylinder with a female and male thread quick-change structure at both ends. From the perspective of thread structure design and water (air) holes, the requirements of the drill rod at both ends of the center of the hole are smaller. If the same hole diameter as the body of the conventional hollow steel structure, it will not only increase the weight of the drill rod, which is not conducive to drilling operations but also increase the manufacturing cost of the drill rod.

From the perspective of the force of the drill rod, the force at the threads at both ends of the drill rod is large, and the force on the rod body is small. Under normal rock drilling conditions, the fracture of the drill rod is mainly in the thread of the broken body. Therefore, the reasonable structure of the guide rod is the center hole of both ends is small, and the center hole of the rod body is large. This center hole reducer structure uses conventional hollow steel roll forming, which is difficult to achieve with welding. The most reasonable method is to weld the two end joints and the rod body into one. Friction welding is the first choice for various welding methods because its inherent weld strength is higher than the parent material’s strength.

Considering the different needs of friction welding, heat treatment, and drill rod strength, 23CrNi3Mo is used for drill rod joints and rods. Using low-alloy ultra-high-strength structural steel can reduce welding stress and facilitate subsequent carburizing treatment, which can perfectly combine welding and heat treatment. The joint is produced by round steel bars, and the rod body is formed by rolling.

The main process route is as follows: rolling blank → rough machining → friction welding → post-weld tempering → CNC machining shape → profiling thread turning → carburizing heat treatment

How to choose the right hydraulic guide rod?

When choosing a hydraulic guide rod, we need to consider the following factors:

  • Drilling depth and hole diameter: according to the specific drilling needs and hole diameter requirements, select the appropriate length and diameter of the drill rod.
  • Geological conditions: choose the appropriate drill rod material and structure type according to the geological conditions. For example, when drilling in hard rock, we should select drill rod materials with high hardness and wear resistance.
  • Budget and cost: choose a hydraulic guide rod product with high-cost performance according to the budget and cost requirements.


As an essential part of modern engineering, hydraulic guide rods have greatly improved the efficiency and accuracy of engineering operations. Its wide application reflects the rapid development of rock drilling engineering technology and highlights the human pursuit of efficient construction.

With the continuous advancement of science and technology, the design of hydraulic guide rods will be more optimized, the performance will be more excellent, and it will provide more robust support for various complex projects. In the future, we look forward to more innovations and applications of hydraulic guide drill rod technology, which will lead us into a new era of more efficient engineering construction.

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