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12
MANTA I
Revision 03/05, Effective Date March 2, 2005
13
MANTA I
Revision 03/05, Effective Date March 2, 2005
PROBLEM
Low
Penetration
Rate Under
Prevailing
Drilling
Paramters
Heavy
Wear at
Steel Tube
No return of
fluid
WHAT TO DO?
1. Check fluid
return.
2. Check motor
speed range
3. Check wear
picture of bit
face
Check where
fluid is leaking.
INDICATION
Fluid not muddy.
Evidence of steel
cuttings
Bit worn out.
Diamond without
exposure.
(flush with matrix)
Face of bit
plugged with
cuttings
Face of bit
covered with steel
Steel cuttings stick
to bit face.
Wear picture of
polished diamonds
Deep grooves.
Heavy Wear.
SOLUTION/ RECOMMENDATIONS
Adjust drilling parameters to
recommendations for reinforcement
See recommended
speeds
Replace with new bit
Increase bit load
Reduce RPM, or resharpen bit
Break core, clean bottom of hole or
reduce RPM and drill with increased
bit load
Clean bit face by sharpening methods
such as drilling dry at low RPM in a
concrete block 3/8” deep max.
Increase water flow rate
Clean bit face by drilling in concrete
block.
Reduce RPM
Increase bit load
Use lower speed; increase bit load
Adjust guidance on carraige
Adjust guidance on carraige
Nicks or dirt on mounting faces
Replace bit.
Improve flushing.
Replace bit
If Leaking can be tolerated; continue
drilling with increased attention.
CAUSE
Drilling in steel
reinforcement
Speed not correct for
the bit size used
Insufficient bit load
Rotated with
high RPM on
reinforcement
Loose material at
bottom of hole
Not enough fluid
pumped. Cuttings
burnt to matrix.
Diamonds prevented
from cutting
Steel cuttings stick to
bit face. Diamonds
prevented from
cutting
Bit load too low
Bit speed too high
Worn or open guide
ways on cradle.
Borehole is getting
undulated
Protruding steel.
Spindle is offset.
Bit out of true
Bit is deformed.
Poor cleaning of
abrasive cuttings.
Crown clearance
worn out.
Troubleshooting
When trouble occurs, be sure to check the simple causes which, at first, may
seem too obvious to be considered. Refer to the table below for problems and
their possible causes.