Roller Cutter Bits

NOMINAL BIT SIZE {in inches) API TOLERANCE

P.D.C. cutters are self sharpening and continue to drill until they are worn to approximately semi-circular shape.

The percentage cutter wear figures given are based on the area of cutter that has been used divided by the area of a semi-circular cutter. (Because of this it is possible to obtain wear greater than 100%.)

It should be noted that although the LIFE of the P.D.C. cutter is related to the given % wear figure, the life of the bit may vary widely depending on other conditions.

Therefore, the decision of whether or not to re-run the bit should be based on not only cutter wear but on other factors such as:

Number of missing or damaged cutters and their positions. Wear on cutters adjacent to missing cutters. Maximum cutter wear.

gauge condition (P.D.C. cutters and diamonds). Erosion.

Overall bit condition. Section left to drill. Formation.

Up to 23% wear use the "Flat Width" and over 23% use "Remaining Cutter Depth".

Flat Width mm

Remaining Depth mm

% Worn

4

1 %

5

2

6

4

7

7

6

10

9

16

10

11

23

10.5

30

10

39

9.5

47

9

56

8.5

65

8

75

7.5

84

7

93

6.5

103

6

112

5.5

FZJ\T WIDTH

0 0

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