The main objectives of this report are to confirm the applicability of the methods for the estimation of rock strength and tooth wear to insert bits. These methods were obtained from the test results of the milled tooth bits with different tooth wear as described in the 2nd report. Therefore, drilling tests were conducted using 101.6mm-dia insert bits with different tooth wear. The main results obtained from the tests are as follows: 1. The relation between the effective axial energy per revolution divided by bit diameter (Feu/Nd) and the effective rotary energy per revolution divided by cross-sectional area of bit squared ((8Te/d2)2), is the information which shows the rock strength independent of tooth wear. The drilling strength of rock (Ds) can be obtained from the relation between them.
2. The relations between Ds and the penetration strength of rock (Is), Ds and the specific energy calculated from the effective rotary energy (Se), Ds and the threshold weight per unit length of bit diameter (Fc/d), are effective information to estimate the tooth wear quantitatively.
From these results, it became clear that the methods for the estimation of rock strength and tooth wear obtained from the milled tooth bits are applicable to the insert bits.
