Infrastructure / Overburden Cased Drilling
Casing Bits
CASING BITS
Boart Longyear offers a large selection of casing bits to perform in a wide variety of ground conditions. Casing bits are designed for rotary percussive or rotation-only drilling based on the tungsten carbide inserts used and the bit’s geometry. Customized tools for unique drilling applications are also available upon request.
Construction
Casing bit bodies are constructed of high-strength quenched-and-tempered steel. The high-quality tungsten carbide inserts are induction brazed into the steel bodies, ensuring a secure fit without overheating issues associated with flame brazing. Strict machining control of the carbide seats prevents premature loss of carbide inserts.
Gauge Protection
Tungsten carbide gauge protection on casing bits prevents excessive wear to the bit’s outer diameter in abrasive ground conditions. Additionally, in unconsolidated conditions where the ground is caving in on the drill string, gauge protection helps free the bit and casing by providing an additional cutting surface.
SHRINK FIT CARBIDES
When required, Boart Longyear offers shrink-fit installation of all hemispherical, ballistic, and two-step tungsten carbide inserts instead of the standard induction brazing. This very precise construction method is often utilized when drilling in extremely hard ground conditions and provides both increased button retention and longer overall life.
ADVANTAGES
- Computer-controlled induction brazing of tungsten carbide inserts for superior process control and overheating prevention, common with flame brazing
- High-grade body construction with quenched and tempered steels
- Optional tungsten carbide gauge protection available for unconsolidated grounds and increased bit life in abrasive conditions
- Specialized designs for unique drilling situations, such as drilling through reinforced concrete and drilling without inner bits
Hemispherical Button Type, Design A
Designed for percussive drilling in hard ground conditions but can be used universally for all rock ground conditions when drilling with percussion.
Ballistic Button Type, Design A
Casing bit design for percussive drilling as well as some rotary drilling. Ballistic buttons offer more aggressive penetration rates in medium-hard ground conditions when drilling with percussion.
Scraping Button Type, Design A
Designed as a good alternative for both rotary and percussive drilling. The tungsten carbide insert geometry allows for some percussive drilling while also providing an efficient cutting action for rotary drilling.
Bladed Type, Design B
The thread length of overburden casing varies by casing diameter and thread type.
Type C
Ballistic / Scraping
Scraping Button With Gauge Protection, Design E
The Scraping Button type drill bit is available with gauge protection to maintain outer diameter and assists in freeing casing in unconsolidated grounds.
Scalping Button With Gauge Protection, Design F
This bit is designed exclusively for rotary drilling. The tungsten carbide design enables efficient material removal during rotation. This bit can be purchased with either a variety of rotary percussive threads or double-start cylindrical threads specifically for use with rotary casing.
Scalping Buttons With Wear Protection For Reinforced Concrete, Design Fc
Designed for drilling through reinforced concrete. The additional carbides in this bit provide the additional cutting performance to get through common reinforced construction materials. This bit should only be used for rotary drilling.
Two-Step Button With Gauge Protection, Design V
Designed for rotary percussive drilling, the two-step button is a balance between the more aggressive ballistic tungsten carbide and the hemispherical button used in hard grounds. This bit can perform well in a wide range of harder ground conditions.
W-Type Without Wear Protection, Design W
Arrangement of small and larger ballistic carbides allow for superior percussive drilling performance when the straightness of the hole is critical. The larger center buttons minimize hole deviation while performing the primary cutting action. The outer buttons perform the secondary cutting providing efficient penetration rates.
Type-Z Hemispherical
Type-Z Ballistic
Type-Z Octagonal
Type-Z 3-Flat
Type-Z Scraping
Extra Lobe Bit, Design H
Lobe and eccentric designed bits allow for drilling without the use of an inner drill string. The additional carbide cutting area replaces the need for an inner drill bit. The concave or convex placement of the lobe simulates the placement of the normal inner drillstring bit (advanced or following) to the casing bit.
CONCAVE
CONVEX
PLANAR
ECCENTRIC BIT, DESIGN ECC
BIT WITH CUTTING BLADE, DESIGN FG
Cutting blade bits are designed for rotational drilling without an inner drill string. The cutting blade is knocked off the bit and left in the hole during anchor and grout installation.
On request, the cutting blade can be supplied with additional hard facing and additional carbide cutting inserts.