Carbon Steel Machining

DEK delivers carbon steel machining in 1018, 1045, 1215 and 12L14 to ±0.005 mm on CNC mills, lathes and Swiss-type turning centers. Our sweet spot: Swiss-turned free-machining grades for small, high-precision parts.

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±0.005mm
General Tolerance
3 days
Prototype Lead Time
No MOQ
From a Single Part

CNC turning of a mild steel stepped shaft

ISO 9001:2015 Certified AS9100D and ISO 13485 certified

Why Choose DEK for Carbon Steel Machining

Mild steel is simply the trade term for low-carbon grades, so a drawing calling out “mild steel” or “carbon steel” lands here. Carbon steel costs less and cuts faster than alloy steel, which makes it the default for general-strength parts.

We run 3-, 4- and 5-axis CNC milling, CNC and Swiss-type turning (our sweet spot for 1215 and 12L14), EDM, grinding and tapping. A single prototype in 1018 or 1045 ships as fast as 3 days, and the same process scales into production without re-quoting.

±0.005 mm on general features
1.2M+ critical parts machined a year
98.6%+ on-time delivery rate
ISO 9001, AS9100D, ISO 13485 via TUV

Carbon Steel Grades We Machine

Three grade groups cover most custom carbon steel parts, from ductile low-carbon stock to leaded and resulfurized free-machining bar.

1018
~440 MPa (cold-drawn), ~126 HB
1018 carbon steel machining suits general shafts, brackets and pins; machinability ~78%.
1045
~565–625 MPa, ~170–200 HB
1045 carbon steel machining for gears, axles and higher-strength shafts; bar and plate.
1215 / 12L14
~136% / ~170% machinability
Resulfurized 1215 and leaded 12L14, ~150 HB, for bushings, fittings and screw-machine parts. See 12L14 machining.

Four machined mild steel components with threaded holes and smooth finishes

±0.003mm
Sub-10 mm micro parts
±0.01mm
5-axis profile control
~1000 mm
Size envelope

Precision Carbon Steel CNC Machining

Each carbon steel part goes to the process that fits its geometry, from prismatic milled blocks to small-diameter Swiss-turned components.

1

Multi-Axis Milling

Pockets, flat faces and complex profiles on prismatic parts across 3-, 4- and 5-axis centers, with ±0.01 mm profile control on contoured geometry.
2

CNC & Swiss Turning

Round, shaft-like parts on CNC lathes, with tight OD tolerances on small diameters through Swiss-type turning.
3

Drilling, Tapping & EDM

Threaded holes tapped in the same setup, no secondary operation; slots, internal corners and hardened features cut by EDM machining.
4

Cylindrical Grinding

Shaft and pin ODs ground to sub-0.005 mm roundness with cylindrical grinding after turning.

DFM Considerations for Carbon Steel

Four issues our engineers flag before cutting carbon steel, so grade, tooling and sequence match the print.

1

1018 Gums Up Under Light Cuts

Low carbon and ductility cause built-up edge on finish passes; sharp coated tooling and higher feed rates keep the surface clean.
2

12L14 Raises Compliance Flags

Its lead additive can rule it out for medical implant contact and some RoHS/REACH-restricted applications. Confirm end-use before you specify it.
3

Distortion After Hardening

Hold rough stock oversize before heat treatment, then finish-machine or grind critical dimensions afterward to compensate for warp.
4

Rougher Finish on Resulfurized

1215 and 12L14 finish rougher than 1018. If the print calls for a fine surface finish, flag it early so we set grade and cutting parameters.

Carbon and Mild Steel Grades We Machine

Detailed pages for 1018, 1045, 1215 and 12L14 plus structural mild steel grades, each with properties, applications and quote options.

Carbon Steel vs Alloy Steel: Which Should You Choose?

Carbon steel is the default for general-strength parts; alloy steel earns its cost where hardenability matters. Full trade-off in alloy steel vs carbon steel.

Criteria	This MaterialCarbon Steel	Alloy Steel
Choose it for	General-strength parts	Gears, tooling
Cost	Lower	Higher
Cutting speed	Cuts faster	–
Alloying	Plain carbon	Cr, Mo or Ni added
Hardenability	–	Higher
Typical grades	1018, 1045, 12L14	4140, 4340

Where Custom Carbon Steel Parts Are Used

Carbon steel goes where cost control and strength matter more than corrosion resistance, from drivetrains to production-line fixtures.

Surface Finishing for Carbon Steel Parts

Bare carbon steel rusts faster than stainless; a CNC machining + finish callout matched to indoor, outdoor or washdown use resolves it.

Surface Treatments

Zinc Plating
Black Oxide
Phosphate Coating
Powder Coat

Need another finish? See all CNC machining + finish options

Carbon Steel Machining FAQ

Answers on rust protection, heat treatment and tolerances for machined carbon steel parts.

How do you protect carbon steel parts from rust during shipping?

Parts are typically coated with zinc plating, black oxide, phosphate or oil before shipment, since bare machined carbon steel can flash-rust in transit under humidity or condensation. Specify the finish on your RFQ if the part won't be plated downstream right after receiving.

Can carbon steel parts be heat-treated after machining?

Yes. Carbon steel can be heat-treated after machining to raise hardness or strength for load-bearing applications. Note the target hardness or heat-treat spec on your drawing so it is confirmed during quoting, and expect a rough-then-finish sequence to control post-treatment distortion.

What's the tightest tolerance you can hold on carbon steel?

±0.005 mm on general features, ±0.01 mm profile control on 5-axis contoured geometry, and down to ±0.003 mm on sub-10 mm micro-precision components. Fit-critical features such as shaft-bore pairs hold ±0.005 mm.