Metal Drill Bits

Substrate selection: Standard HSS, Cobalt, or Solid Carbide

Base material determines heat dissipation, feed rate tolerance, and operational lifespan. Standard high-speed steel (HSS) grades, such as HSS 6542, perform reliably across mild steel, iron, copper, and aluminum under intermittent workshop use. For routine maintenance and low-alloy work, standard HSS provides adequate toughness against deflection shock.

When machining heat-treated steels or austenitic grades, step up to cobalt drill bits. Tooling made from M35 Cobalt High-Speed Steel contains 5% cobalt (HSS-Co 5%), while HSSE-PM grades utilize powder metallurgy with M42 Cobalt High-Speed Steel (HSS-PM Co 8%). Cobalt retains cutting-edge hardness at red heat, preventing edge breakdown on stainless steel. For continuous production milling and CNC boring, Solid Tungsten Carbide provides maximum hardness and thermal stability across diameters from 1.0 - 20.0 mm.

• Standard HSS (such as HSS 6542): Cost-effective drilling in carbon steel, brass, copper, and aluminum.
• M35 Cobalt (HSS-Co 5%): Built for stainless steel, iron, and tough ferrous metals where heat buildup ruins standard edges.
• M42 Powder Metallurgy (HSS-PM Co 8%): Extreme thermal resilience for repetitive drilling in hard metals to DIN338 standards.
• Solid Tungsten Carbide: Rigid tooling for automated CNC metalworking requiring tight dimensional stability.

Tool geometry: Twist drills vs. step cone cutters

Jobber twist drill bits remain the production standard for through-hole creation in solid stock, bar, and structural sections. Standard twist profiles clear chips efficiently through deep flutes, supporting uniform cutting from small diameters like 1.0 mm - 3.0 mm through to larger production holes up to 1-13 mm.

For thin plate and sheet metal punching, step drill bits eliminate bit grabbing and deburr the entry edge simultaneously. Flute configurations like a spiral groove balance cutting pressure and clear swarf smoothly. Common stepped ranges include 4-12 mm, 4-20 mm, and 4-32 mm, allowing multiple hole diameters with a single tool without changing collets.

• Jobber twist drill: Deep-flute drilling in bar, plate, and tube up to 1-13 mm.
• Step twist drill bit: Single-sheet hole expansion and thin sheet metal punching from 3-13mm or 4-32 mm.
• Through-coolant twist drill bit: Direct fluid delivery to cutting tips on deep industrial boring cycles.

Surface coatings and shank configurations

Protective surface coatings reduce friction and prolong tool life between regrinds. Titanium coated bits reduce galling when running dry in standard ferrous materials. AlTiN (Aluminum Titanium Nitride) coatings excel in high-heat machining environments, forming an aluminum oxide protective barrier that resists degradation in stainless steel work.

Match your machine drive chuck to the correct shank geometry to prevent slipping under load. Standard chucks accept round shank and straight shank bits. Portable drills and impact drivers benefit from a 1/4-inch Hex Shank (Quick Change) measuring 6.35 mm. For higher torque loads on step cutters, a triangle shank or 3-flat shank locks firmly into keyed three-jaw chucks.