7. Rock Cutting Tools and Assessing Drillability

Question 1

Bit Life

Answer 1

drilling length between grindings

Question 2

Cerchar Test

Answer 2

for abrasivity assessment and wear prediction

Question 3

Vickers Hardness Values

Answer 3

determines the mineral content of rock

Question 4

Abrasion Value

Answer 4

measures the loss of weight of test bit after 100 revolutions in five minutes on crushed rock powder

Question 5

Brittleness Test

Answer 5

ability of rock to resist crushing by repeated impacts

Question 6

What are the 4 stages in the penetration of a hard sphere into a hard, brittle solid?

Answer 6

1. elastic contraction
2. ring crack and start of conical crack
3. crushing of cone and start of chip formation
4. continued crushing + departure of chips

Question 7

Characteristics of a round carbide shape?

Answer 7

strong configuration against fracture

Question 8

Characteristics of a semi-ballistic carbide shape?

Answer 8

wear resistant and high penetration rate

Question 9

Characteristics of a ballistic carbide shape?

Answer 9

higher penetration rate than semi-ballistic

Question 10

Characteristics of a spike carbide shape?

Answer 10

highest penetration rate and weak configuration against fractures