Indexable vs Solid Carbide Drills: Which Should You Use?

Drilling holes faster and cheaper is one of the highest-leverage improvements in any machine shop. The choice between indexable and solid carbide drills determines hole quality, cost-per-hole, and cycle time.

Quick Decision Matrix

• Hole diameter < 12mm → Solid carbide always wins
• 12–25mm diameter, depth < 3×D → Indexable drill (cheaper per hole)
• Depth > 5×D → Solid carbide with internal coolant or gun drill
• Hole tolerance H8 or better → Solid carbide + reaming

Solid Carbide Drills — Strengths

Solid carbide drills offer superior hole quality (typically IT9–IT10 straight from the drill), tighter tolerances, and excellent surface finish. The one-piece construction transmits torque efficiently and resists chatter. Best for production drilling of repeating hole sizes.

Premium options: Sandvik CoroDrill 460, Walter A3782, OSG ADO series. Coatings like AlTiN extend life by 3–5× over uncoated.

Indexable Drills — Strengths

Indexable drills with replaceable carbide inserts give you flexibility: one drill body covers a diameter range (e.g. 16–20mm with different inserts), and replacement inserts cost a fraction of a new solid drill. They handle interrupted cuts and uneven surfaces better.

Trade-off: hole tolerance is wider (typically IT12), surface finish is rougher. Not suitable for tight-tolerance work without secondary operations.

Cost Analysis Example

Drilling 10,000 holes of 20mm diameter, 30mm deep in 1045 steel:

• Solid carbide drill: $280 drill, ~800 holes/regrind, 3 regrinds = 3,200 holes total. Cost = $280/3,200 = $0.09 per hole
• Indexable drill: $450 body + $25 insert pair × 200 hole life = $25/200 = $0.13 per hole (body cost amortized)

For this case, solid carbide wins on cost. But if hole sizes vary across jobs, indexable amortizes the body across more parts and wins.

When Speed Matters Most

Indexable drills run 30–50% faster cutting speeds than solid carbide because the inserts dissipate heat better and chip evacuation is easier. For production drilling where cycle time = money, this matters.

Browse the Catalog

Hooguu stocks solid carbide drills from Sandvik, Walter, OSG, Mitsubishi, and indexable drills from Sandvik, Iscar, Kennametal. See the full drill catalog.