Solid Carbide Drills — Through-Coolant and Standard

Compiled 2026-04-04 · 40 chunks, 13 posts · carbide-drills · through-coolant · drilling · speeds-feeds · tool-selection

Summary

Solid carbide drills represent the premium solution for production [[drilling]], offering 10-20x the tool life of HSS/cobalt drills while running 3-5x faster. Made from tungsten carbide (cemented carbide), these tools excel in CNC machining centers but require proper setup and parameters. Through-coolant variants provide superior chip evacuation and heat management for deep holes, while standard carbide drills handle general production work. Critical considerations include brittleness requiring rigid setups, specific speeds/feeds by material, and coating selection for application optimization.

Drill Types and Selection Guide

Standard Solid Carbide Drills

Best for: General production drilling up to 5xD depths, materials from aluminum to hardened steels

  • Harvey 17950/17950-C3: 0.1094" diameter, 2-flute, available uncoated or AlTiN
  • Harvey 37512/37512-C8: 0.187" diameter, TiB2 coating option for abrasive materials
  • Harvey 849560/849560-C3: 0.125" diameter, balanced geometry for steel/aluminum

Through-Coolant Drills

Best for: Deep holes (8xD+), difficult materials, high-production environments

  • Enable continuous coolant flow through drill body
  • Eliminate peck drilling in most applications
  • Conservative starting point: 130 SFM for [[304-stainless]]
  • Do not peck drill with through-coolant - go straight through per experienced machinists

Micro Drills (Under 0.100")

Critical applications: Electronics, medical devices, precision holes

  • Harvey 11020/11020-C3: 0.0312" diameter, AlTiN coating reduces galling
  • Harvey 17902/17902-C3: 0.0156" diameter, ultra-precision applications
  • Run higher RPM but lower feed rates: 15,000-25,000 RPM typical

Speeds and Feeds by Material

Steel (1018-4140 Range)

  • Surface Speed: 200-400 SFM (manufacturer), 150-250 SFM (shop floor conservative)
  • Feed Rate: 0.002-0.008 IPR depending on diameter
  • Example: 1/4" drill in [[4140-steel]]
  • RPM = (200 × 3.82) ÷ 0.25 = 3,056 RPM
  • Feed = 3,056 × 0.004 = 12.2 IPM

Stainless Steel (304/316)

  • Surface Speed: 100-180 SFM (avoid work hardening)
  • Feed Rate: 0.003-0.006 IPR (maintain constant feed)
  • Critical: Never let drill dwell or rub - causes [[work-hardening]]
  • Through-coolant conservative: 130 SFM per forum experience

Aluminum (6061/7075)

  • Surface Speed: 400-800 SFM
  • Feed Rate: 0.004-0.012 IPR
  • Coolant: Flood coolant or mist, avoid built-up edge
  • Some machinists report better results dry in specific aluminum grades

Titanium (Ti-6Al-4V)

  • Surface Speed: 80-150 SFM
  • Feed Rate: 0.002-0.005 IPR
  • Critical: Constant feed, sharp tools only, through-coolant preferred
  • Example from forum: 3/4" drill at 0.0045 IPR producing acceptable chips

Hardened Steel (45+ HRC)

  • Surface Speed: 50-120 SFM
  • Feed Rate: 0.001-0.003 IPR
  • Setup: Rigid toolholders essential, pilot holes recommended
  • Real example: 300 RPM for 3/4" hole through hardened hay spear

Coating Selection Guide

Uncoated Carbide

  • Applications: Non-ferrous metals, aluminum, some steels
  • Advantage: Sharpest edge, lowest cost
  • Harvey Examples: 849540, 37509, 11040

AlTiN (Aluminum Titanium Nitride)

  • Applications: Steel, stainless steel, cast iron
  • Advantage: High-temperature resistance, general purpose
  • Harvey Examples: 11020-C3, 17950-C3, 849560-C3

TiB2 (Titanium Boride)

  • Applications: Abrasive materials, high-silicon aluminum
  • Advantage: Superior wear resistance
  • Harvey Examples: 11493-C8, 37512-C8

Machine Requirements and Setup

Essential Requirements

  • Minimum: CNC machining center or high-quality drill press
  • Avoid: Hand drills, worn spindles, poor rigidity
  • Toolholders: Hydraulic, shrink-fit, or precision collets only
  • Runout: Less than 0.0005" TIR for micro drills, 0.001" for larger

Coolant Considerations

  • Through-coolant: 100-300 PSI for deep holes
  • Flood: Standard for general drilling
  • Dry: Some machinists prefer for aluminum, copper alloys
  • Note: Thermal shock can reduce tool life in some steels per academic research

Common Problems and Solutions

Drill Breakage

Causes: Excessive feed, poor rigidity, dull drill, chip packing Solutions:

  • Reduce feed rate by 50% for troubleshooting
  • Check spindle/toolholder condition
  • Use through-coolant for chip evacuation
  • Never spot drill carbide drills (not required per shop experience)

Poor Hole Quality

Causes: Wrong speeds/feeds, drill wear, insufficient coolant Solutions:

  • Monitor chip formation - should be continuous, not powder
  • Check for built-up edge on drill margins
  • Verify coolant concentration and flow

Short Tool Life

Manufacturer vs. Reality: Catalogs often list aggressive parameters

  • Start at 70% of manufacturer's recommended SFM
  • Increase gradually based on chip formation and tool wear
  • Document what actually works for your setup/materials

Shop Floor Tips

Breaking-In New Drills

  • Run first 10-20 holes at 80% recommended feed
  • Allows cutting edge to strengthen gradually
  • Particularly important for micro drills

Deep Hole Drilling

  • Through-coolant drills: No pecking required
  • Standard drills: Peck every 2-3 diameters
  • Reduce feed 50% for last 0.1" before breakthrough
  • Spindle orient and slow retract to avoid bell-mouthing

Troubleshooting Chips

  • Powder/dust: Feed too low, speed too high
  • Long stringy: Good for steel, problematic for aluminum
  • Blue chips: Excessive heat, reduce speed or increase coolant

Cost Considerations

  • Calculate cost per hole, not cost per drill
  • Carbide drills typically lowest cost per hole in production
  • 1000-2000 holes typical vs. 100 holes for HSS/cobalt
  • [[drill-selection]] — Comprehensive drill type comparison and selection criteria
  • [[drilling]] — General drilling operations, techniques, and troubleshooting
  • [[toolholder-selection]] — Critical for carbide drill success and runout control
  • [[4140-steel]] — Specific parameters for this common material
  • [[304-stainless]] — Stainless steel drilling techniques and work hardening prevention
  • [[titanium-ti6al4v]] — Specialized approach required for titanium drilling
  • [[chatter-vibration]] — Rigidity requirements and vibration elimination
  • [[tool-wear-diagnosis]] — Identifying wear patterns and optimizing replacement timing