DRILLSTAR CARBIDE TOOLS ARE WORKING IN MANY PLACES AROUND THE WORLD
BTA Single Tube and Ejector Twin Tube Deep Hole Drills represent two advanced configurations of the BTA drilling system, optimized for different deep-hole machining needs. The Single Tube Drill is designed for straightforward deep-hole drilling in medium-to-large diameters (12–300mm), utilizing a single coolant tube for chip evacuation through the annular space. The Ejector Twin Tube Drill, conversely, employs a dual-tube system with an ejector nozzle to create a venturi effect, enhancing chip evacuation efficiency in ultra-deep holes (≥100x D) or materials with tenacious chip formation.
Both systems prioritize precision, rigidity, and process stability, making them suitable for demanding applications in aerospace, energy, ad heavy industry. The choice between single and twin tube depends on hole depth, diameter, and workpiece material, with twin tube designs excelling in challenging scenarios where reliable chip removal is critical to prevent tool failure.
Single Tube Drills:
Simplified Design: Single steel tube with integrated cutting head, ideal for standard deep-hole applications (depth ≤5 meters, diameter ≥12mm).
Cost-Effective: Fewer components reduce initial tooling cost, while replaceable carbide tips extend service life.
Versatile Cooling: High-pressure coolant (80–150 bar) flows through the tube interior, flushing chips outward between the tube and workpiece.
Ejector Twin Tube Drills:
Dual-Tube Construction: Inner tube delivers coolant to the cutting edge; outer tube, combined with an ejector nozzle, creates a vacuum effect to accelerate chip evacuation, even at low coolant pressures (50–100 bar).
Ultra-Deep Capability: Handles depths up to 15 meters with consistent straightness (≤0.03mm/m), critical for drilling gun barrels, nuclear reactor channels, and oil country tubular goods (OCTG).
Chip Control Assurance: Venturi effect breaks up long chips and increases evacuation velocity, reducing the risk of chip jams in sticky materials like stainless steel and titanium.
Common Features:
Precision Cutting Heads: Carbide inserts with PVD coatings (TiN, TiCN) for reduced friction; CBN tips for hardened steel (≥50 HRC).
Rigidity Enhancement: Heavy-wall tubes (wall thickness ≥10% of diameter) and anti-vibration guide pads to minimize tool deflection.
Customization Options: Adjustable cutting diameters (via replaceable guide rings), modular tube extensions for variable depths, and specialized geometries for through-hole or blind-hole machining.
Single Tube Drills:
Automotive: Deep holes in diesel engine cylinder liners (cast iron) and transmission housings (aluminum alloys).
General Engineering: Machining hydraulic cylinders and press-fit shafts in carbon steel, where hole straightness and surface finish (Ra ≤1.6μm) are essential for component assembly.
Ejector Twin Tube Drills:
Aerospace: Deep holes in nickel-based superalloy turbine disks (Inconel 718) for cooling channels, requiring flawless chip evacuation to prevent tool breakage.
Oil & Gas: Drilling high-precision holes in sour service components (H2S-resistant alloys), where even small chip blockages could lead to costly downtime.
Defense: Production of gun barrels and missile guidance system tubes, demanding extreme straightness (≤0.01mm/m) and surface finish (Ra ≤0.8μm) for ballistic performance.
Q: When should I choose a twin tube over a single tube drill?
A: Use twin tube for depths >5 meters, diameters <20mm, or materials with stringy chips (e.g., low-carbon steel, annealed stainless steel). Single tube is preferable for larger diameters and simpler applications.
Q: What is the ejector nozzle’s role in twin tube drills?
A: The nozzle creates a pressure differential that speeds up chip evacuation, similar to a vacuum cleaner. This is especially useful when coolant pressure is limited or chip volume is high.
Q: Can these drills be used with automated tool changers?
A: Yes, both designs are compatible with standard BTA tool holders and CNC machine interfaces, enabling seamless integration into automated machining cells.
Q: How do I troubleshoot chip jams in twin tube systems?
A: First, check coolant pressure and flow rate—ensure they meet material-specific recommendations. If issues persist, switch to a more aggressive chip-breaker insert geometry or reduce feed rate to promote smaller chip formation.
BTA drilling is a deep hole drilling process that uses a specialized drilling tool on a long drill tube to produce deep holes in metal, from holes with a diameter of 20 mm [0.80 in] and larger, up to depth-to-diameter ratios of 400:1. BTA drilling is the most effective method of drilling deep holes, as it is a cleaner, more reliable and capable process than conventional twist drills, and can achieve larger diameters and higher feed rates than the alternative gundrilling.
BTA drilling tool heads are threaded or mounted onto long drill tubes, and use multiple cutting surfaces on a single tool to remove chips efficiently, exhausting them using high-pressure coolant through holes in the tool head, then out the drill tube and through the machining spindle. BTA tooling is available in brazed or inserted carbide configurations.
BTA stands for Boring and Trepanning Association, and is also sometimes referred to as STS (single tube system) drilling, as it uses one single drill tube for the BTA tool, compared to other processes such as ejector drilling, which use two.
BTA drilling is a deep hole drilling method which was created by the Boring and Trepanning Association in the 1940’s. It comprises of a special hollow tooling that allows pressurized coolant to flow into the hole on the outside of the drill, and evacuates chips through an internal hole in the drill.
Depending on the depth and diameter of the hole needing to be drilled, the BTA tooling will consist of a hollow drill tube that it attached to a threaded indexable cutter head. BTA drilling has an effective diameter range of 20-200mm (0.80″-8.00″) and can reach depths of up to 400mm (16.00″).
Botek manufacture a wide range of BTA single tube and ejector twin tube deep hole drills from Ø7.76mm through to Ø500mm, and larger as special application tools.
BTA drills are used on dedicated machinery where the coolant is induced through a pressure head and the chips are then evacuated through the centre of the drill and the drill tube. Tube dampers are used to support the drill tube and prevent vibration and distortion of the tube, and work steadies support the work piece if required.
Ejector drills are used on conventional and CNC type machines. They use an inducer to feed coolant between the inner and outer twin tube system with the chips being ejected through the centre of the inner tube. With CNC machines now utilising high pressure coolant Botek are able to offer alternatives to the ejector system.
Solid drill heads with brazed carbide inserts are available from Ø7.76mm to Ø65mm. These heads can be reground and re-tipped / re-coated but are considered a consumable item and therefore have a limited life.
Indexable inserted drill heads are available from Ø15mm upward and allow quick insert changes and on heads above Ø25mm the ability to adjust the cutting diameter.
Counterboring heads with indexable inserts are available from Ø28.5mm upward and allow holes to be bored out to larger sizes after solid drilling. As they use less power than solid drill heads, larger diameters can be produced on machines with limited power.
Trepanning heads are available from Ø55mm and produce an inner core that can be reused saving material costs.
BTA Single Tube and Ejector Twin Tube Deep Hole Drills represent two advanced configurations of the BTA drilling system, optimized for different deep-hole machining needs. The Single Tube Drill is designed for straightforward deep-hole drilling in medium-to-large diameters (12–300mm), utilizing a single coolant tube for chip evacuation through the annular space. The Ejector Twin Tube Drill, conversely, employs a dual-tube system with an ejector nozzle to create a venturi effect, enhancing chip evacuation efficiency in ultra-deep holes (≥100x D) or materials with tenacious chip formation.
Both systems prioritize precision, rigidity, and process stability, making them suitable for demanding applications in aerospace, energy, ad heavy industry. The choice between single and twin tube depends on hole depth, diameter, and workpiece material, with twin tube designs excelling in challenging scenarios where reliable chip removal is critical to prevent tool failure.
Single Tube Drills:
Simplified Design: Single steel tube with integrated cutting head, ideal for standard deep-hole applications (depth ≤5 meters, diameter ≥12mm).
Cost-Effective: Fewer components reduce initial tooling cost, while replaceable carbide tips extend service life.
Versatile Cooling: High-pressure coolant (80–150 bar) flows through the tube interior, flushing chips outward between the tube and workpiece.
Ejector Twin Tube Drills:
Dual-Tube Construction: Inner tube delivers coolant to the cutting edge; outer tube, combined with an ejector nozzle, creates a vacuum effect to accelerate chip evacuation, even at low coolant pressures (50–100 bar).
Ultra-Deep Capability: Handles depths up to 15 meters with consistent straightness (≤0.03mm/m), critical for drilling gun barrels, nuclear reactor channels, and oil country tubular goods (OCTG).
Chip Control Assurance: Venturi effect breaks up long chips and increases evacuation velocity, reducing the risk of chip jams in sticky materials like stainless steel and titanium.
Common Features:
Precision Cutting Heads: Carbide inserts with PVD coatings (TiN, TiCN) for reduced friction; CBN tips for hardened steel (≥50 HRC).
Rigidity Enhancement: Heavy-wall tubes (wall thickness ≥10% of diameter) and anti-vibration guide pads to minimize tool deflection.
Customization Options: Adjustable cutting diameters (via replaceable guide rings), modular tube extensions for variable depths, and specialized geometries for through-hole or blind-hole machining.
Single Tube Drills:
Automotive: Deep holes in diesel engine cylinder liners (cast iron) and transmission housings (aluminum alloys).
General Engineering: Machining hydraulic cylinders and press-fit shafts in carbon steel, where hole straightness and surface finish (Ra ≤1.6μm) are essential for component assembly.
Ejector Twin Tube Drills:
Aerospace: Deep holes in nickel-based superalloy turbine disks (Inconel 718) for cooling channels, requiring flawless chip evacuation to prevent tool breakage.
Oil & Gas: Drilling high-precision holes in sour service components (H2S-resistant alloys), where even small chip blockages could lead to costly downtime.
Defense: Production of gun barrels and missile guidance system tubes, demanding extreme straightness (≤0.01mm/m) and surface finish (Ra ≤0.8μm) for ballistic performance.
Q: When should I choose a twin tube over a single tube drill?
A: Use twin tube for depths >5 meters, diameters <20mm, or materials with stringy chips (e.g., low-carbon steel, annealed stainless steel). Single tube is preferable for larger diameters and simpler applications.
Q: What is the ejector nozzle’s role in twin tube drills?
A: The nozzle creates a pressure differential that speeds up chip evacuation, similar to a vacuum cleaner. This is especially useful when coolant pressure is limited or chip volume is high.
Q: Can these drills be used with automated tool changers?
A: Yes, both designs are compatible with standard BTA tool holders and CNC machine interfaces, enabling seamless integration into automated machining cells.
Q: How do I troubleshoot chip jams in twin tube systems?
A: First, check coolant pressure and flow rate—ensure they meet material-specific recommendations. If issues persist, switch to a more aggressive chip-breaker insert geometry or reduce feed rate to promote smaller chip formation.
BTA drilling is a deep hole drilling process that uses a specialized drilling tool on a long drill tube to produce deep holes in metal, from holes with a diameter of 20 mm [0.80 in] and larger, up to depth-to-diameter ratios of 400:1. BTA drilling is the most effective method of drilling deep holes, as it is a cleaner, more reliable and capable process than conventional twist drills, and can achieve larger diameters and higher feed rates than the alternative gundrilling.
BTA drilling tool heads are threaded or mounted onto long drill tubes, and use multiple cutting surfaces on a single tool to remove chips efficiently, exhausting them using high-pressure coolant through holes in the tool head, then out the drill tube and through the machining spindle. BTA tooling is available in brazed or inserted carbide configurations.
BTA stands for Boring and Trepanning Association, and is also sometimes referred to as STS (single tube system) drilling, as it uses one single drill tube for the BTA tool, compared to other processes such as ejector drilling, which use two.
BTA drilling is a deep hole drilling method which was created by the Boring and Trepanning Association in the 1940’s. It comprises of a special hollow tooling that allows pressurized coolant to flow into the hole on the outside of the drill, and evacuates chips through an internal hole in the drill.
Depending on the depth and diameter of the hole needing to be drilled, the BTA tooling will consist of a hollow drill tube that it attached to a threaded indexable cutter head. BTA drilling has an effective diameter range of 20-200mm (0.80″-8.00″) and can reach depths of up to 400mm (16.00″).
Botek manufacture a wide range of BTA single tube and ejector twin tube deep hole drills from Ø7.76mm through to Ø500mm, and larger as special application tools.
BTA drills are used on dedicated machinery where the coolant is induced through a pressure head and the chips are then evacuated through the centre of the drill and the drill tube. Tube dampers are used to support the drill tube and prevent vibration and distortion of the tube, and work steadies support the work piece if required.
Ejector drills are used on conventional and CNC type machines. They use an inducer to feed coolant between the inner and outer twin tube system with the chips being ejected through the centre of the inner tube. With CNC machines now utilising high pressure coolant Botek are able to offer alternatives to the ejector system.
Solid drill heads with brazed carbide inserts are available from Ø7.76mm to Ø65mm. These heads can be reground and re-tipped / re-coated but are considered a consumable item and therefore have a limited life.
Indexable inserted drill heads are available from Ø15mm upward and allow quick insert changes and on heads above Ø25mm the ability to adjust the cutting diameter.
Counterboring heads with indexable inserts are available from Ø28.5mm upward and allow holes to be bored out to larger sizes after solid drilling. As they use less power than solid drill heads, larger diameters can be produced on machines with limited power.
Trepanning heads are available from Ø55mm and produce an inner core that can be reused saving material costs.
