Roller cone drill bits are used in drilling larger diameter wells. The drilling efficiency of the roller cone drill bit depends on the wear rate of the materials that forms bit teeth, which crushes the rock at the bottom of the well. To prevent excessive wear, research has largely focused on the study and determination of abrasion-resistant materials. In our work, we investigated the wear mechanism of a roller cone drill bit whose wear-resistant teeth are protected by a hard metal coating welded onto the teeth. The difference between material properties of erosion-protective carbide coating and the tooth steel leads to uneven wear of bit teeth. In order to determine the material changes, we carried out detailed studies of the rock through which drilling was carried out, the drilling parameters and the materials of which the roller cone bit is made. The principle of wear of the tooth materials and their carbide coating, determined by our research, indicated the guidelines which could be basis for the development of abrasion-resistant materials could be carried out, as well as the problem of applying an erosion protection to the teeth of the studied type of roller cone bits.

In geotechnology and mining, tools and equipment interact with aggressive geological material, causing the wear of these components. For this reason, it is important to determine the rate of abrasivity of individual geological materials, depending on the type of interaction with the tool. Various abrasivity tests have been developed in laboratories. Some of them are general, while others are special. What they all have in common is that they attempt to determine the abrasivity of rocks or soils in relation to the wear of the test specimens. This article gives an overview of the laboratory test methods for assessing the abrasivity of geological materials, which are useful in the field of geotechnology and mining engineering. General and special abrasivity tests are presented in detail. The aim of the article is to present existing laboratory tests to assess the abrasivity of rocks and soils, based on which further investigations of wear can be considered as part of a comprehensive approach to this tribological problem. Understanding of the wear mechanisms is the basis for the development of wear-resistant tools and models for predicting the tool life.

The breakdown of the drill bit or rapid decrease of the rate of penetration during the drilling process results in a delay in the progress of drilling. Scientists and engineers are increasingly focusing on research to extend the bit life and improve the drilling rate. In our work, “in situ” drilling parameters were monitored during the drilling process with the roller cone drill bit IADC 136, diameter 155.57 mm (6 1/8"). After drilling, the bit was thoroughly examined to determine the damage and wear that occurred during drilling. The following modern and standardized investigative methods were used: an analysis of rock materials and an analysis of micro and macrostructure materials of the roller cone bit. Analyses were carried out using optical and electron microscopy, a simultaneous thermal analysis of materials of drill bit, analysis of the chemical composition of materials of drill bit, and a determination of the geomechanical parameters of rock materials. The resulting wear, local bursts, and cracks were quantitatively and qualitatively defined and linked to the drilling regime and the rock material. The results of our investigation of the material of the roller cone bit can serve as a good base for the development of new steel alloys, which can resist higher temperatures and enable effective drilling, without structural changes of steel material.