T38 89mm Flat Face Button Bit for Rock Drilling
The T38 89mm flat face dome button bit is a top hammer drilling tool engineered for heavy-duty bench drilling, underground tunnelling and open-pit quarrying in medium to hard rock formations. Designed with a high-rigidity flat face profile and a heavy-duty 13-button array, this 3.5-inch bit delivers efficient power transfer, high gauge wear resistance and a long service life.
Product Overview
Featuring 8 outer gauge buttons (13mm) to hold exact hole diameter and prevent gauge shrinkage, plus 5 central front buttons (12mm) for rapid rock core shattering, the T38 89mm bit balances gauge protection with center crushing efficiency. The dome (spherical) button geometry provides high fracture toughness against extreme impact energy, reducing chipping risks in broken or hard rock strata.
Main Applications
- Bench Drilling: Heavy-duty production drilling in open-pit and underground mining.
- Underground Tunnelling: Precision drilling for mine development and tunnelling projects.
- Quarrying: Blast-hole drilling in granite, limestone and marble quarries.
- Production Drilling: The 89mm hole diameter provides a suitable blast-hole size for efficient fragmentation.
Key Features & Advantages
- 13-Button Dual-Diameter Configuration: Eight 13mm outer gauge buttons hold the exact hole diameter and prevent gauge shrinkage, while five 12mm central front buttons shatter the rock core rapidly.
- Spherical / Dome Button Geometry: Provides high fracture toughness against extreme impact energy, reducing chipping risks in broken or hard rock strata.
- Flat Face Stability: The flat head face optimizes force distribution across the entire bit profile, enhancing hole straightness and minimizing drill rod deviation under high impact.
- Heavy T38 Thread Body: Forged from heat-treated alloy steel for long thread fatigue life, compatible with top hammer rigs.
- Even Impact Distribution: Distributes impact forces across all 13 buttons, preventing localized stress concentrations in heavy percussive drilling.
Product Specifications
| Thread Connection |
T38 (Top Hammer Thread) |
| Bit Diameter |
89 mm (3 1/2 inch) |
| Face Design |
Flat Face |
| Button Type |
Dome / Spherical |
| Button Layout |
13 Buttons: Gauge 13mm x 8 + Front 12mm x 5 |
| Skirt / Body Type |
Normal / Standard Body |
| Body Material |
High-Strength Forged Alloy Steel |
| Carbide Grade |
Heavy-Duty Tungsten Carbide |
| Primary Application |
Bench Drilling, Production Drilling, Underground Tunnelling, Quarrying |
FAQ
Q1: What are the primary rock drilling applications for a T38 89mm flat face button bit?
A: It is engineered for medium-to-hard rock bench drilling, open-pit quarrying, production drilling and heavy underground tunnelling. The T38 thread connection handles high percussive impact from modern hydraulic rock drills, while the 89mm (3.5 inch) hole diameter provides a suitable blast-hole size for efficient fragmentation.
Q2: Why is the dual-size button arrangement (13mm gauge + 12mm front) used on this T38 89mm bit?
A: Eight 13mm gauge buttons withstand severe abrasive friction at the perimeter, preventing loss of hole gauge and premature bit tapering, while five 12mm center buttons break down the central rock face uniformly without choking flushing channels.
Q3: What are the advantages of a flat face profile over a concave face for an 89mm T38 bit?
A: Flat face bits offer high structural strength and versatile performance across hard, solid or fractured rock. Unlike concave bits, which excel in directional control in soft-to-medium rock, flat face bits distribute impact forces evenly across all 13 buttons, preventing localized stress concentrations and providing high fatigue resistance during heavy percussive drilling.
Q4: How do dome (spherical) buttons compare with ballistic buttons on a T38 89mm bit?
A: Dome buttons offer high impact toughness and wear life in hard, abrasive or fissured rock where percussive energy is extreme. While ballistic buttons penetrate faster in soft, non-abrasive rock, dome buttons are less prone to chipping or shearing in demanding hard-rock applications.
Q5: How can drill rig operators extend the service life of a T38 89mm threaded button bit?
A: Regrind carbide buttons when flat wear spots reach one-third of the button diameter, maintain sufficient air or water flushing pressure to prevent re-drilling rock dust, and keep proper feed force to avoid collar bounce that can fracture carbides or excessive pressure that overheats threads.
