Foundation Drilling Case
MH-3 Roller Bit Core Barrel
for 1200mm Bored Pile Rock Drilling
Field support in Guangzhou Zengcheng, China, covering MH-3 roller bit
installation, core barrel repair, spoil discharge improvement, and operating
parameter adjustment in hard weathered rock.
Location
Guangzhou
Zengcheng
Rig
SANY SR415R
Tool
1200mm Core Barrel
Cutter
MH-3 Roller Bit
Record
About 57m Rock Drilling
Project Background
Hard rock drilling is a tool system problem, not only a cutter problem.
The site required 1200mm bored pile drilling through upper soil and weathered formations into harder rock. Before the rebuild, the site had experienced cutter seizure, dropped rollers, uneven wear, mud packing, and vibration during drilling.
Drillnova reviewed the original core barrel, cutter position, formation condition, drilling parameters, and on-site repair constraints before proposing the rebuild and operating suggestions
Rock samples observed on site included hard crystalline rock and weathered layers.
Field Diagnosis
The main causes of abnormal roller bit damage
The field log showed that roller bit life was affected by multiple site factors. These findings guided the rebuild plan and later tool improvement ideas.
1
Rotation and pressure
High rotation speed and heavy pressure in hard rock increased vibration, bearing heat, and impact load on the roller bits.
2
Spoil discharge
Limited water or mud circulation made cuttings dry, causing mud packing around the cutters and higher body wear.
3
Tool matching
Kerf mismatch between the bullet tooth barrel and the roller bit barrel increased back-side wear on some cutters.
Drillnova Solution
On-site rebuild plus
practical drilling guidance
The work focused on making the existing 1200mm barrel more suitable for hard rock operation and giving the operator practical suggestions for reducing cutter damage.
The existing barrel was measured and checked before the cutter rebuild.
Field Results
Recorded performance from follow-up inspections
The figures below are taken from the site communication log. They are field records from this project, not a universal lifetime guarantee for every formation.
1200mm
Core barrel diameter used for the bored pile work
4.79m
Recorded drilling progress in one monitored section
0.7m/h
Average rock drilling speed in that recorded section
57m
Approximate cumulative rock drilling recorded later on site
Engineering Learnings
What this case proved
The MH-3 roller bit barrel achieved useful drilling progress, but the site also showed where tool life could be improved. The strongest finding was that roller bit performance depends on cutter quality, barrel design, flushing, and operation together.
Use lower speed in hard rock
Lower rotation speed helped reduce vibration and bearing heat.
Improve cuttings removal
More water or slurry and better guide strips reduce mud packing.
Protect the roller back
Back-side protection inserts can reduce body wear in mismatched grooves.
Inspect abnormal rollers early
Replacing damaged rollers in time helps prevent larger tool failure.
Follow-up inspection identified broken teeth, bearing seizure, and body wear causes.
Related Tools
Tools used or recommended for
similar projects
Roller Bit
Heavy-duty roller bit for core barrels drilling tools working in hard formations.
Roller Bit Core Barrel
Custom core barrel design for bored pile drilling for stable hard rock penetration.
Project Support
Need a roller bit solution for
hard rock piling?
Send us your pile diameter, drilling depth, rig model, ground condition, and current tool photos.
Drillnova can recommend roller bit type, cutter layout, barrel structure, and operating suggestions for your jobsite.