Carbide Drill Bits

What is a carbide drill bit?

A carbide drill bit is a drill made from solid tungsten carbide — much harder and more heat-resistant than high-speed steel (HSS). Carbide drills allow higher cutting speeds and last significantly longer in difficult materials such as hardened steel, stainless steel, cast iron and abrasive composites. Carbide is brittle and should only be used in rigid setups (drill press, CNC, lathe), never in a hand drill. AIMS Industrial stocks solid carbide drill bits in uncoated, TiN and TiAlN coatings.

When should you use a carbide drill bit instead of HSS?

Carbide is the right choice for drilling hardened steel (above 40 HRC), abrasive composites such as carbon fibre and fibreglass, cast iron, high-volume stainless steel work, and any production drilling where tool-change frequency must be minimised. For mild steel, aluminium and most general drilling, standard HSS is the better economic choice.

What are the carbide drill coatings used for?

Uncoated carbide is the default for non-ferrous materials and aluminium. TiN (titanium nitride) extends life by 2-3 times in general steel work. TiAlN (titanium aluminium nitride) handles the highest cutting temperatures and is the standard coating for high-speed dry drilling of hardened steel and stainless steel.

Solid Carbide Drill Bits — Quick Reference

Use solid carbide for drilling hardened steel (>40 HRC), abrasive composites, cast iron and stainless steel in production volumes. Carbide is harder and more heat-resistant than HSS, allows higher cutting speeds, and lasts significantly longer in difficult materials. Carbide is brittle — use only in rigid machine setups (drill press, CNC, lathe), never in a hand drill.

For tougher-than-HSS but lower-volume work, see cobalt drill bits — they bridge the gap between HSS and carbide. For drill bit sizing reference, see the drill bit metric and imperial size chart.

Solid Carbide Drill Bits — Hardened Steel, Stainless & Composite Drilling

Solid carbide drill bits are the correct tool for drilling hardened steel, abrasive materials, stainless steel, cast iron and composites where high-speed steel (HSS) drills would rapidly dull or fail. The tungsten carbide substrate is significantly harder and more heat-resistant than HSS, allowing higher cutting speeds and longer tool life in difficult materials. AIMS Industrial supplies solid carbide drills for engineering workshops, toolrooms and machining operations across Australia.

Browse drill bit options at AIMS:

• Solid carbide drill bits — this page — for hardened, abrasive and stainless materials
• Cobalt drill bits (M35, M42) — bridge between HSS and carbide for stainless and tough alloys
• Standard HSS jobber drills — the general workshop drill for mild steel, aluminium, plastics
• Centre drills — spotting and starter holes
• Browse the full drilling range

When to use carbide vs HSS

HSS drills are the right choice for the majority of drilling tasks — mild steel, aluminium, copper, brass and most engineering plastics. Carbide becomes the correct specification when:

• Drilling hardened steel or tool steel above 40 HRC
• Drilling abrasive materials including graphite, fibreglass and carbon fibre composites
• Drilling cast iron, which contains hard abrasive phases that rapidly dull HSS
• High-production drilling where tool-change frequency must be minimised
• Drilling stainless steel in production quantities where HSS tool life is insufficient

For tougher-than-HSS but not-yet-carbide work — particularly stainless and work-hardening alloys in lower volume — cobalt drill bits bridge the cost/performance gap. Cobalt drills handle stainless and tough alloys at HSS prices.

Carbide drills should not be used in hand drills or non-rigid setups — they are brittle and will snap if subjected to the flex and run-out of a hand-held drill. They require a rigid machine (drill press, CNC machining centre or lathe) for safe and effective use.

Coatings & grades

AIMS stocks solid carbide drills in uncoated, TiN (titanium nitride) and TiAlN (titanium aluminium nitride) coatings. Uncoated carbide is the default for non-ferrous and lower-temperature applications. TiN extends life by 2-3× in steel applications. TiAlN handles the highest cutting temperatures and is the standard coating for high-speed dry drilling of hardened steel and stainless. The carbide grade itself (micrograin sizes typically 0.5-1.0 micron) affects toughness vs wear resistance — finer grains for harder materials, coarser for tougher work.

Drill bit sizing & tap drill calculations

For complete drill bit size reference (metric and imperial cross-reference, fractional vs decimal equivalents, drill point geometry), see our drill bit size chart — one of the most-used reference articles on the site. For tap drill sizing (the drill diameter required before threading), see the threading tap size chart.

Companion ranges at AIMS

Solid carbide drills sit within our broader drilling range. For drill chucks, adaptors and accessories, see drill chucks and drill accessories and adaptors. For step drilling, see step drill bits. Reduced-shank carbide drills for larger diameters in standard chucks are catalogued under reduced shank drill bits.

For help selecting the right carbide drill grade, coating and geometry for your material and machine, call (02) 9773 0122 or contact our team.

People Also Ask — Carbide Drill Bits

Q: When should I use a solid carbide drill bit over HSS or cobalt?

Solid carbide is the right choice when you need to drill hardened steel above 40 HRC, when production volume justifies the cost (typically 500+ holes per bit needed), or when you're running high-speed CNC or mag drill setups with rigid clamping. For handheld drilling, low-volume jobs, or general workshop use, HSS or HSS-Cobalt is usually the smarter spend — carbide is brittle and shatters under shock or misalignment that hand drilling creates.

Q: What does TiAlN coating do on a carbide drill bit?

TiAlN (Titanium Aluminium Nitride) is a black-purple PVD coating that gives the drill excellent heat resistance — making it the right choice for hardened steel, stainless steel, and high-temperature drilling. Critical limit: TiAlN does NOT work on aluminium. The aluminium content in the coating reacts with aluminium in the workpiece, causing built-up edge and rapid tool failure. For aluminium use uncoated bright carbide, ZrN or DLC coating instead.

Q: Is solid carbide better than cobalt for stainless steel?

It depends on the volume. For drilling 304 or 316 stainless at production speeds, solid carbide with TiAlN coating runs 3-5 times faster than cobalt and lasts much longer per bit. For occasional stainless drilling on a workshop drill press, cobalt M35 or M42 is more cost-effective and more forgiving of slight misalignment. Carbide's brittleness means it needs a rigid setup to survive.

Q: Can carbide drill bits be resharpened?

Not by users. Carbide is too hard for standard sharpening equipment and requires specialist diamond-wheel regrinding at a tooling regrinder. For production users running high carbide volume, sending bits out for regrind makes economic sense. For workshop users, carbide bits are typically replaced rather than reground — the freight and turnaround cost outweighs the savings on smaller diameters.

Q: What point angle should a carbide drill bit have?

140 degree split point is the modern carbide standard, designed for aggressive engagement with hardened materials and reduced thrust force. The sharper 140 degree point self-centres on hard surfaces without wandering and produces cleaner hole entry than the older 118 degree HSS standard. Most premium carbide drills come as 140 degree split point out of the box.