Machining 1018 and 1045 Carbon Steel

Compiled 2026-04-04 · 40 chunks, 15 posts · carbon-steel · mild-steel · 1018 · 1045 · speeds-feeds · turning

Summary

1018 and 1045 carbon steels are among the most commonly machined materials in general machine shops. 1018 is a low-carbon mild steel with excellent machinability, while 1045 contains more carbon (0.43-0.50%) making it slightly harder but still very machinable. Both materials are forgiving for beginners yet capable of excellent surface finishes when machined properly. The key challenges are managing built-up edge formation on 1018 and avoiding work hardening on both grades.

Speeds and Feeds

Turning Operations

1018 Steel:

  • HSS Tools: 80-120 SFM, 0.008-0.020" IPR feeds, 0.050-0.200" DOC
  • Carbide Inserts: 300-600 SFM, 0.005-0.015" IPR feeds, 0.100-0.300" DOC
  • Finishing: 400-500 SFM, 0.003-0.008" IPR, 0.015-0.030" DOC

1045 Steel:

  • HSS Tools: 60-100 SFM, 0.006-0.015" IPR feeds, 0.050-0.150" DOC
  • Carbide Inserts: 250-450 SFM, 0.005-0.012" IPR feeds, 0.075-0.250" DOC
  • Finishing: 300-400 SFM, 0.003-0.006" IPR, 0.015-0.025" DOC

Milling Operations

1018 Steel:

  • HSS End Mills: 80-150 SFM, 0.002-0.008" IPT, 0.050-0.200" axial DOC
  • Carbide End Mills: 400-800 SFM, 0.003-0.010" IPT, 0.100-0.300" axial DOC
  • Face Milling: 500-750 SFM, 0.005-0.015" IPT, 0.050-0.150" DOC

1045 Steel:

  • HSS End Mills: 60-120 SFM, 0.002-0.006" IPT, 0.050-0.150" axial DOC
  • Carbide End Mills: 300-600 SFM, 0.003-0.008" IPT, 0.075-0.250" axial DOC
  • Face Milling: 400-600 SFM, 0.004-0.012" IPT, 0.040-0.120" DOC

RPM Calculation: RPM = (SFM × 3.82) / Tool Diameter (inches)

Drilling Operations

Both materials drill well with standard [[drilling]] parameters:

  • HSS Twist Drills: 50-100 SFM, 0.003-0.008" IPR
  • Carbide Drills: 200-400 SFM, 0.004-0.012" IPR
  • Use cutting fluid for holes deeper than 3× diameter

Turning Inserts

For 1018:

  • CNMG 432/434: Uncoated or TiN coated carbide, positive rake geometry
  • WNMG 432: For heavier cuts, 0.031" corner radius typical
  • Sharp edge inserts preferred to minimize built-up edge

For 1045:

  • CNMG 432: TiN or TiAlN coated, slightly negative to neutral rake
  • WNMG 432/434: For roughing operations
  • Link to [[cnmg-inserts]] and [[wnmg-inserts]] for detailed specifications

End Mills

Roughing (Both Materials):

  • 3-5 flute carbide, uncoated or TiAlN
  • 30-45° helix angle
  • Sharp cutting edges for 1018, slightly honed for 1045

Finishing:

  • 4-6 flute carbide with corner radius
  • Variable helix to reduce [[chatter-vibration]]
  • Coated tools (TiAlN, AlCrN) for extended tool life

Drilling Tools

  • Standard 118° point angle HSS or carbide
  • [[indexable-drills]] for production work
  • Coolant-fed drills recommended for deep holes

Common Problems

Built-Up Edge on 1018

The biggest challenge with 1018 is built-up edge (BUE) formation due to its low carbon content and tendency to stick to cutting tools.

Solutions:

  • Increase cutting speed to push above BUE formation zone (typically >300 SFM with carbide)
  • Use sharp, positive rake geometry tools
  • Apply cutting fluid consistently
  • Avoid dwelling or stopping mid-cut

Poor Surface Finish

Contrary to common belief, excellent surface finishes are achievable on both materials.

For 1018:

  • Use higher speeds (500+ SFM) with carbide tools
  • Light finishing passes (0.015-0.030" DOC)
  • Sharp tools with 0.015-0.031" nose radius
  • Consistent feed rate to avoid surface irregularities

For 1045:

  • More forgiving than 1018 for surface finish
  • Standard finishing parameters work well
  • Watch for work hardening if multiple spring passes are taken

Work Hardening

Both materials can work harden, but 1045 is more susceptible.

Prevention:

  • Maintain consistent feed rates
  • Avoid rubbing or dwelling
  • Keep tools sharp
  • Take full-depth cuts rather than multiple light passes

Tool Life Issues

Excessive wear:

  • Reduce speed, increase feed
  • Check for proper [[chip-control]]
  • Ensure adequate coolant flow

Premature chipping:

  • Usually from too aggressive entry or interrupted cuts
  • Reduce feed rate on entry
  • Use more gradual lead-ins

Shop Floor Tips

Real-World Speeds vs. Catalog

Many experienced machinists run these steels faster than catalog recommendations:

  • 1018 with carbide: 600-800 SFM common in production (vs. 300-500 catalog)
  • Face milling 1018: 750+ SFM with proper insert selection
  • Forum users consistently report better finishes at higher speeds

Tooling Selection Reality

What works in practice:

  • Uncoated carbide often outperforms coated on 1018 due to sharper edge
  • 5-flute end mills provide good balance of strength and finish
  • Corner radius tools (0.015-0.031") essential for good finish on 1018

Setup Considerations

Workholding:

  • Both materials clamp well, minimal distortion issues
  • Watch for scale on hot-rolled stock affecting part dimensions
  • Cold-rolled 1018 machines cleaner than hot-rolled

Programming Tips:

  • Conventional milling often preferred for 1018 to prevent BUE
  • Climb milling acceptable with rigid setup and sharp tools
  • Avoid rapid direction changes that can cause work hardening

Coolant Strategies

Flood coolant: Best for heavy roughing and drilling Mist coolant: Often sufficient for light milling operations Dry machining: Possible with carbide at appropriate speeds, but finish may suffer on 1018

Material Variations

1018: Cold-rolled machines better than hot-rolled due to scale and surface quality 1045: Annealed condition preferred; normalized material can be slightly more abrasive Flame-cut stock: Expect hard edge layer requiring heavier first cuts

  • [[4140-steel]] — higher strength carbon steel comparison
  • [[cast-iron]] — similar speeds but different tooling requirements
  • [[turning-basics]] — fundamental lathe operations for steel
  • [[face-milling]] — techniques for flat surface generation
  • [[cnmg-inserts]] — primary insert choice for turning operations
  • [[endmill-types]] — selection guide for milling applications
  • [[chip-control]] — managing chip formation in steel machining
  • [[surface-finish-problems]] — diagnosis and solutions for finish issues
  • [[tool-wear-diagnosis]] — identifying and preventing premature tool failure