BTA Deep Hole Drills

Overview

BTA Deep Hole Drills are specialized cutting tools designed for machining deep cylindrical holes (depth-to-diameter ratio ≥10:1) with exceptional precision and efficiency, following the BTA (Boring and Trepanning Association) drilling system principles. These drills feature a single-tube design where coolant and chips are evacuated through the annular space between the drill tube and the workpiece, enabling stable operation in challenging materials like stainless steel, titanium, and nickel-based superalloys.

Constructed with a carbide-tipped cutting head and a high-strength steel tube, BTA drills are engineered to withstand high axial forces and maintain hole straightness (≤0.02mm/m) even at depths up to 12 meters. Their modular design allows easy replacement of worn cutting tips, while advanced geometries optimize chip control and reduce cutting forces, making them indispensable in industries requiring deep-hole machining with tight tolerances.

Features

Efficient Chip Evacuation:

Single-tube system with internal coolant flow (50–200 bar) flushes chips outward through the annular gap, preventing blockages and reducing tool wear.

Chip-breaker grooves on the cutting edge ensure consistent chip size (≤10mm length) for smooth evacuation in deep holes.

High-Precision Cutting Heads:

Carbide inserts (grades K10–K30) or CBN tips for machining hardened steels (up to 65 HRC), with precision-ground rake angles (5°–15°) to minimize cutting forces.

Adjustable 导向条 (wear pads) maintain concentricity by riding against the bore wall, reducing vibration and improving hole roundness (≤0.03mm deviation).

Robust Construction:

Heavy-wall steel tubes with internal ribbing for enhanced torsional rigidity, capable of withstanding axial forces up to 80,000N in tough materials.

Heat-treated shanks (45–50 HRC) for durability in high-speed operations (spindle speeds 500–3,000 RPM).

Customizable Configurations:

Available in diameters 12–300mm and lengths up to 15 meters, with options for straight or helical flutes depending on material chip formation characteristics.

Specialized designs for through-holes, blind holes, and stepped holes, with optional internal cooling nozzles for extreme-depth applications.

Material Compatibility:

Optimized for ferrous materials (carbon steel, alloy steel, stainless steel) and difficult-to-machine alloys (Inconel, Hastelloy), with surface coatings (TiAlN, AlCrN) to reduce friction and enhance wear resistance.

Applications

Oil & Gas Equipment: Drilling deep holes in hydraulic fracturing pumps (stainless steel 17-4PH) and subsea valve bodies, ensuring dimensional accuracy for critical sealing surfaces.

Heavy Machinery: Machining large-diameter holes (50–200mm) in construction equipment components (e.g., excavator boom cylinders), where hole straightness impacts hydraulic system performance.

Power Generation: Fabrication of steam turbine shafts and generator rotors from high-strength low-alloy (HSLA) steel, requiring deep boreholes for weight reduction and internal inspections.

Aerospace Tooling: Deep-hole drilling in titanium alloy fixture plates for aircraft assembly, maintaining positional accuracy within ±0.05mm over 5-meter depths.

FAQ

Q: How does BTA drilling differ from gun drilling?

A: BTA uses a single-tube system with external chip evacuation, ideal for diameters >12mm and deep depths. Gun drilling uses a smaller-diameter double-tube system with internal chip flow, suitable for 3–20mm diameters.

Q: Can BTA drills be used for non-ferrous metals like aluminum?

A: Yes, but lower coolant pressure (50–80 bar) and sharp carbide grades (K10) are recommended to prevent chip welding and maintain surface finish.

Q: What maintenance is required for drill tubes?

A: Inspect tubes for straightness (using laser alignment) and replace if deflection exceeds 0.1mm/m. Clean coolant channels after each use to remove debris and prevent blockages.

Q: Do you offer reconditioning services for worn drills?

A: Yes, we provide tip replacement, tube straightening, and coating reapplication, restoring drills to 90% of original performance at 50% of new tool cost.

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.