Point Angle
Standard 118° point angles suit soft metals and general steel. Steeper 135° to 140° point angles shorten chip length and reduce work-hardening in stainless steel and titanium.
CNC Drilling Technical Guide
CNC Drills Design Guide: Precision Geometry for High-Speed Holemaking
This technical guide details the core principles of drill bit design, web thinning techniques, flute geometries, and custom tool engineering for high-performance holemaking.
Technical overview
Principles of Engineering High-Performance CNC Drills
Optimizing the design of CNC drill bits is essential for achieving straight hole axes, excellent surface finishes, and maximum tool life. Holemaking presents unique chip-evacuation and thermal-friction challenges because cutting velocity drops to zero at the absolute center of the tool. Effective CNC drilling tools balance web strength, point self-centering capability, and open flute volume for continuous chip evacuation.
Core geometry
Fundamental Parameters in CNC Drill Design
Chisel Edge & Web Thinning
S-gash or split-point web thinning reduces axial thrust forces, limits tool wander, and allows a CNC drill setup to self-center without spot drilling.
Web Thickness & Core Taper
A heavy central web increases beam strength to resist deflection during deep-hole drilling, while a back taper reduces friction along the margin.
Margin Configuration
Double-margin designs provide secondary support along the hole wall, improving hole straightness and roundness in deep-hole applications.
Chip and heat control
Advanced Chip Evacuation & Internal Coolant Delivery
Efficient chip evacuation helps prevent chip packing, tool breakage, and hole-wall scarring during continuous drilling cycles.
Parabolic Flute Designs
Open, curved flute profiles increase chip space and allow deep-hole drilling up to 10×D to 30×D without frequent pecking cycles.
Through-Coolant Channels
Helical internal coolant holes deliver high-pressure fluid directly to the cutting lips, rapidly flushing chips while cooling the chisel edge.
Polished Flute Valleys
Mirror-finished flute surfaces reduce friction and help prevent chip welding in sticky non-ferrous aluminum and copper alloys.
Workpiece materials
Tailoring Drill Geometries to Workpiece Substrates
Aluminum & Light Alloys
Use high helix angles of 30°–38°, ultra-sharp cutting edges, polished open flutes, and DLC or ZrN coatings to eliminate material galling.
Hardened & Stainless Steels
Heavy web cores, 140° split points, micro-honed cutting edges, and AlTiN or nACo coatings withstand heat and work-hardening.
Cast Iron & Abrasive Materials
Flat 140° point angles, reinforced corner chamfers, and high-wear carbide substrates resist abrasive margin wear.
Composites & CFRP
Specialized double-angle or dagger-point geometries shear abrasive fibers cleanly to prevent exit delamination and burring.
Drill types
CNC Drilling Tools by Category
Bauron manufactures a complete range of drilling tools, grouped by application. Each category diagram below is paired with the specific drill types it contains.
A. General-Purpose Drills
Versatile drills for everyday holemaking across a wide range of materials.
- Jobber Length Drills — versatile choice for general drilling
- Screw Machine Length Drills — shorter length for extra rigidity
- Stub Length Drill Bits — compact, for shallow holes and tight spaces
- Extra Long-Length Drill Bits — deep drilling with added rigidity
- Taper Shank Drills — secure fit for heavy-duty work
- Reduced Shank Drills — larger diameters in standard holders
- Large Diameter / Oversized Drills — bigger holes without special setups
B. Special Drills (Flute Variation & Micro)
Specialized flute geometries and micro sizes for demanding or delicate work.
- Double Margin Straight Flute Drills — added stability, reduced deflection
- Straight Flute Drills — ideal for brittle materials like glass and ceramics
- Micro Drill Bits — precision drilling in small, delicate components
- Three Flute Drill Bits — improved material removal and smoother cutting
- Twist Micro Drills — high-speed drilling in fine applications
C. Wood Drills
Purpose-built geometries for clean, controlled holes in wood and soft materials.
- Auger Drill Bits — deep, clean holes in wood
- Forstner Drill Bits — smooth, flat-bottom holes with minimal tear-out
- Plug Cutter Drill Bits — create plugs to conceal screws
- Spade Drill Bits — wide blades for rapid material removal
- Spur / Brad Point Drill Bits — clean, precise holes in wood
D. Masonry & Tile Drills
Built to survive abrasive, brittle materials without cracking the workpiece.
- Masonry Drill Bits — withstand brick, concrete, and stone
- Glass / Tile Drill Bits — drill brittle materials without cracking
E. Deep-Hole Drills
Engineered for extended reach with straight, accurate hole axes.
- Deep Hole Drills — extended reach with high accuracy
- Gun Drills — high-precision deep-hole drilling
F. Hole-Preparation Drills
Tools that start and locate holes accurately before finishing operations.
- Spot Drills — start holes with precision
- Center Drill Bits — accurate pilot holes for lathe work
- Pilot Point Drills — precise starts, reduced wandering
G. Hole-Finishing Drills
Combined and finishing geometries for shaped or multi-diameter holes.
- Step Drills — multiple diameters in one operation
- Countersink Drill Bits — beveled edges for screws
- Counterbore Drills — precise flat-bottom holes
- Drill Chamfer Tools — drilling and chamfering in one pass
Shank options
Shank & Tool-Style Options
Every Bauron drill can be produced with the shank interface that best matches your machine and holder. Each shank type below is shown with how it mounts and where it performs best.
Straight Shank
- Profile: uniform cylindrical shape
- Held: clamped into a collet chuck or drill chuck
- Best for: general-purpose tools like drills and end mills
Weldon Shank
- Profile: cylindrical with one flat machined into the shank
- Held: set screws in a side-lock tool holder
- Best for: tools requiring high torque and secure gripping
Threaded Shank
- Profile: cylindrical shank with threads at the end
- Held: screwed into tool holders or extensions
- Best for: tapping and reaming applications
Tapered Shank
- Profile: conical / tapered (e.g. Morse taper)
- Held: fits into matching taper sleeves or spindles
- Best for: machines with taper sockets
Reduced Shank
- Profile: shank diameter smaller than the cutting diameter
- Held: standard collets or chucks
- Best for: when tool diameter exceeds chuck capacity
Technical questions
Frequently Asked Questions
How does point angle selection affect hole quality in CNC drilling?
A flatter point angle, such as 140°, reduces burr formation on exit and creates a shorter chip, making it suitable for tough alloys and automated CNC machining. A sharper point angle penetrates soft materials easily but can cause breakout burrs.
What is the advantage of using custom drill bits over standard drill geometries?
Custom drill bits can combine operations such as step drilling, chamfering, and counterboring in a single step, reducing tool changeover time and cycle cost per part.
Can Bauron manufacture custom carbide CNC drilling tools from specific blueprints?
Yes. Bauron manufactures bespoke step drills, extended-reach deep-hole drills, specialized coolant-through tools, and custom-diameter drill geometries from technical CAD files.
What role do internal coolant channels play in drill performance?
Through-tool coolant channels deliver high-pressure fluid directly to the chisel point, reducing cutting-zone temperatures and flushing chips up the flutes to prevent chip packing in deep holes.
Application support
Collaborate with Bauron on Custom Drill Design
Looking for custom CNC drill bits, step-drill geometries, or high-feed holemaking solutions for your production line? Consult with a Bauron application engineer.
From application details to a production-ready tool.
Bauron works with manufacturers to review tool geometry, substrate, coating, reach, machine conditions, and production requirements for standard and custom CNC tooling.
Submit your requirements