If you landed here, you’re likely choosing between HSS, cobalt, and carbide drill bits—or you already use carbide and want better hole quality, longer tool life, and faster cycles. Below is a practical, engineer-style guide you can use immediately on the shop floor or in procurement.
Use solid carbide when you need high speed, tight tolerance, hard or abrasive materials, or long tool life with stable fixturing. Through-coolant greatly improves chip evacuation and heat control.
Use cobalt (HSS-Co) for tougher (less brittle) drills at lower cost on general steels when setup rigidity isn’t perfect; productivity is lower than carbide but risk is lower.
Match geometry & coating to the material: 135° split-point, TiAlN/AlTiN (high-heat ferrous), polished/flute treatments for aluminum (avoid TiAlN there).
Identify your material and map it to ISO groups (P: steels, M: stainless, K: cast iron, N: non-ferrous, S: superalloys, H: hardened). Each group drives edge prep, coating, and cutting data.
Why it matters: Carbide excels at high speed in P/M/K/S/H when the process is rigid; HSS-Co is more forgiving at low speed.
Solid Carbide (with or without through-coolant): Best combination of penetration rate, precision, and life; can achieve tight hole tolerances and benefits greatly from internal coolant.
Carbide-tipped: Good for abrasive masonry/concrete and some cast irons when you don’t need the precision of solid carbide.
HSS-Co / HSS: Suitable for single holes or less demanding jobs; lower speed but higher toughness.
Point angle & split point: A 135° split-point self-centers, reduces thrust and walking, and works well on alloy steels and stainless; it also chips smaller for better evacuation. 118° is versatile but often needs a pilot in hard metals.
Helix & web: Tough materials benefit from stronger cores; long-chipping materials (e.g., many stainless grades) need flute designs that clear chips efficiently—another reason to pair with through-coolant.
Internal through-coolant improves tool life, chip evacuation, and process security—especially in long-chipping and gummy materials. High-pressure coolant further reduces heat and jams.
Rule of thumb: If chips pack in the flutes, your hole quality and tool will suffer. Increase coolant flow/pressure, reduce feed slightly, or peck (if the drill and application allow).
TiAlN/AlTiN: Excellent heat/oxidation resistance; enables higher cutting speeds and longer life in ferrous materials.
Aluminum & soft non-ferrous (ISO N): Prefer polished flutes or ZrN/DLC-type surfaces; avoid TiAlN in most aluminum jobs due to built-up edge/chip welding risk.
Hole tolerance & surface: Solid carbide drills are favored when you need tighter tolerances and consistent cylindricity/roundness.
Depth (L/D): As depth increases, through-coolant and optimized chip control become non-negotiable; deep-hole families (e.g., 8×D, 12×D, 20×D) exist for this.
Rigidity: Carbide is harder and more brittle—reward it with solid fixturing and minimal runout. If the setup is marginal, cobalt may be safer.
Use OEM cutting data for your exact drill and material, then adjust based on your chips and load. Manufacturer recommendations are a starting point—optimize from there for your machine and coolant.
Carbide drills often reduce cost-per-hole via higher speed, regrindability, and fewer stoppages—especially with internal coolant. Look at tool life, regrinds, scrap, and cycle time together, not just unit price.
General carbon/alloy steels (ISO P), medium depth, CNC, flood or through-coolant available: Solid carbide, 135° split-point, TiAlN-class coating.
Austenitic stainless (ISO M), long chips, heat-sensitive: Solid carbide with through-coolant; focus on chip evacuation (pressure/flow).
Cast iron (ISO K): Solid carbide performs well; cobalt can work at lower speed with good economy if tolerance isn’t tight.
Heat-resistant superalloys (ISO S): Solid carbide with optimized geometry and coolant delivery; follow OEM data closely.
Hardened steels (ISO H): Solid carbide is typically the efficient choice if setup is rigid.
Aluminum (ISO N): Polished, high-evacuation geometry; avoid TiAlN when possible.
Material & ISO group confirmed?
Hole depth (×D) and tolerance defined? (Consider 8×D/12×D solid carbide families if deep.)
Coolant plan (internal vs. external; pressure/flow) set?
Geometry (135° split-point? flute design?) matched to material?
Coating fits the job (TiAlN for ferrous high-heat; polished/ZrN for Al)?
Cutting data source from the drill OEM ready for first cuts?
Solid Carbide Drill Bits (through-coolant options, 3×D): For ISO P/M/K/S/H where tight tolerance and cycle time matter.
Carbide Drill Bits: For abrasive substrates where per-hole precision is secondary.
Cobalt (HSS-Co) Jobber Drills: Cost-effective fallback when rigidity/coolant are limited.
Contact our experts today for a free quote or technical consultation.