Three different drill technologies serve different production needs. Picking right cuts cost-per-hole 50-70%.
Solid Carbide Drills
- Made entirely of carbide — drill body and cutting edges
- Re-grinding possible (3-5× regrinds typical)
- Diameters: 0.5mm to 32mm
- Best hole quality: IT9-IT10 from drill
- Highest cost per drill: $50-500
Indexable Drills
- Steel body with replaceable carbide inserts at tip
- Insert costs 1/10 of solid drill
- Diameters: 12-80mm typical (small inserts limit minimum)
- Hole quality: IT12 typical
- Body cost: $200-800; insert pairs: $20-50
Spade Drills
- Steel body with replaceable spade-shaped insert
- Diameters: 25-150mm
- Hole quality: IT13 (rough)
- Best for large-diameter through-holes
- Body: $100-400; spade: $80-250
Cost-Per-Hole Comparison (Steel)
| Hole | Solid Carbide | Indexable | Spade |
|---|---|---|---|
| 10mm × 30mm | $0.15 | N/A | N/A |
| 16mm × 40mm | $0.25 | $0.18 | N/A |
| 25mm × 60mm | $0.65 | $0.22 | $0.45 |
| 50mm × 100mm | $2.50 | $0.45 | $0.65 |
| 80mm × 100mm | (N/A) | $0.85 | $0.55 |
Decision Matrix
| Requirement | Choose |
|---|---|
| Diameter < 12mm | Solid carbide |
| Tight tolerance (H7) | Solid carbide + ream |
| Volume > 1000 holes/day at 12-40mm | Indexable (lowest cost-per-hole) |
| Diameter > 50mm, low volume | Spade drill |
| Diameter > 50mm, high volume | Indexable |
| Depth > 5×D, any size | Solid carbide with through-coolant |
| Hardened steel any size | Solid carbide nano-coated |
Speed Differences
For 1045 steel:
- Solid carbide drill: Vc = 80-120 m/min
- Indexable drill: Vc = 150-200 m/min (50% faster — chip evacuation easier)
- Spade drill: Vc = 80-150 m/min
Premium Brands
- Solid carbide: Sandvik CoroDrill 460, Walter A3782, OSG ADO
- Indexable: Sandvik CoroDrill 880, Iscar Chamdrill, Mitsubishi WSX
- Spade: Allied Spade Drill, Sandvik Tailormade
See our deeper drill comparison.
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