Türkiye 15.Madencilik Kongresi/15* Mining Congress of Turkey, GäyagüIcr,Ersayin,BiIgen(cds)© 1997, ISBN 975-395-216-3 A CRITICAL REVIEW OF FACTORS INFLUENCING THE WEAR OF THERMALLY STABLE DIAMOND (TSD) ROCK DRILLING BITS

In rock drilling, bit wear is a major factor in determining bit life, the cost of drilling and may significantly influence the drilling method selected for given rock type. Effective control of bit wear can yield significant cost savings. Prediction of cuttability or drillability requires an understanding of the cutting action and the mode of wear and their interaction with the rock propertiesWear type and degree, rate of penetration and life of thermally stable diamond (TSD) bits depends on many complex and interrelated factors. However the important factors in predicting wear rates which are considered in this paper are bit design, bit operating parameters and the characteristics of the penetrated rock under both laboratory and field conditions. The most important bit design characteristics are cutter size, shape orientation, density, profile and hydraulics All these factors are interrelated and require optimisation for the formation properties, the operating parameters of the drilling machine, fluid properties and flow characteristics. The operating parameters include weight on bit, penetration rate, rotational speed, torque, specific energy and die distance drilled. No single rock property indicator gives a satisfactory prediction of wear rates, the determination of the most important properties for a given rock and their effect on wear are discussed. Wear of TSD bits can take many forms, however the most common mechanism during drilling is abrasion Impact loading and accumulated thermal fatigue also contribute to the wear of bits Optimisation of bit design and operating parameters can lead to increased drilling rate, prolonged bit life and reduced drilling cost