Carbon Steel CNC Machining

Carbon steel CNC machined shafts, brackets and gears with black oxide finish

Carbon steel parts we machine cover shafts, brackets, pins, gears, spacers and general industrial components: 1018 low-carbon steel for weldable, general-purpose parts, 1045 medium-carbon where strength and wear matter, 12L14 free-machining steel for high-volume turned work.

Heat treatment is where carbon steel earns its keep — through-hardening, induction hardening and case hardening transform the same geometry into very different parts. We plan grinding allowance and straightening before treatment so finished dimensions still hold.

Material Grades & Properties

Carbon Steel Grades We Machine

GradeStandardCharacteristics
1018ASTM A108Low-carbon, good weldability, general machined parts.
1045ASTM A108Medium carbon; heat-treatable; shafts, gears, strong brackets.
4140ASTM A29Alloy steel, chromoly; high strength and toughness after heat treatment.

Key Properties of Machined Carbon Steel

  • ✓High strength
  • ✓Heat-treatable
  • ✓Cost-effective
  • ✓Requires corrosion protection

Typical tolerances:±0.1 mm as-machined; tighter after grinding

Applications for Carbon Steel Parts

  • Shafts and axles
  • Gears and sprockets
  • Machine frames
  • Tooling and jigs
  • Structural brackets

Machining Notes for Carbon Steel

Free-machining at medium speeds; 4140 in hardened state requires carbide tooling and reduced speeds.

Finishes for Carbon Steel Parts

  • Zinc plating
  • Black oxide
  • Powder coating
  • Painting

Capabilities

  • 1018/1045/12L14/A36 machining to drawing
  • Heat-treatment coordination (through, induction, case)
  • Post-heat-treat grinding coordination
  • Zinc plating and black oxide finishing

Typical materials

Carbon steel 1018, 1045, 12L14, 1144, A36; alloy grades on request.

Material / gradeTypical conditionMachinabilityWhere it fits
Aluminium 6061T6 (solution treated and aged)Easy: free-cutting, good chip controlBrackets, housings, fixtures, prototypes into production
Aluminium 7075T6 / T651Harder: more tool wear, needs rigid setupsHigh-strength, weight-critical parts; not for welding
Stainless 304 / 304LAnnealedWork-hardens: slower speeds, positive feedGeneral corrosion resistance, food and process equipment
Stainless 316 / 316LAnnealedTougher than 304: more tool wearChloride, marine, medical and pharmaceutical exposure
Carbon steel 1018 / 1045As-rolled / normalisedEasy to moderate; needs protection against rustShafts, plates, weldments, tooling bodies
Brass C360H02 half hardExcellent: high speeds, clean finishFittings, bushings, connectors, decorative parts
Copper C110Annealed / H02Gummy: sharp tools and high rake anglesConductivity, busbars, thermal management
Titanium Grade 5 (Ti-6Al-4V)Mill annealedDifficult: low speeds, heat control, tool wearAerospace, medical and lightweight high-strength parts
Engineering plastics (POM, PEEK, PA)Extruded / annealedEasy to gummy: soft jaws, sharp toolingInsulation, low friction, chemical and wear parts

Finishes

Zinc plating, black oxide, phosphate, painted on request, grinding after heat treat.

FinishWhat it doesSpecify it when
As machinedTool marks left visible; Ra typically 1.6-3.2 µmThe part only has to function
Bead blastUniform matte surface, hides tool marksCosmetic parts before anodising
Anodising Type IIBuilds an oxide layer; colour optionsAluminium appearance plus mild corrosion and wear resistance
Hard anodising Type IIIThicker, harder oxide layerSliding or wearing aluminium surfaces
Chromate conversionThin protective film that stays conductiveElectrical bonding or grounding on aluminium
Electroless nickelUniform, hard, corrosion-resistant layerWear plus corrosion, including inside bores
Zinc platingEconomical sacrificial corrosion protectionSteel parts in indoor or sheltered service
Powder coatThick, durable, decorative layerAppearance is the requirement
PassivationRemoves free iron and restores the oxide filmStainless parts after machining
Stress relief / heat treatmentRelieves residual stress before or after cuttingThin walls and tight tolerances that must survive machining

Tolerances

ISO 2768-m standard; ±0.01 mm on critical features.

CalloutWhat it needsEffect on cost and lead time
General: ±0.25 mm / ±0.010 inStandard tooling, dimensional checkBaseline: no adder
Standard: ±0.13 mm / ±0.005 inMachine in good condition, first-article checkSmall adder; the usual quoting default
Tight: ±0.025 mm / ±0.001 inGround or diamond tooling, temperature control, CMMStep change: slower cuts plus full inspection
Precision: ±0.013 mm / ±0.0005 inFinish passes, gauging, controlled environmentMachining dominates the price; often a separate operation
Position / angularity (GD&T)Datum control, one setup where features are relatedDepends on how many setups the datum spans
Surface finish Ra 0.8 µm or finerFiner stepovers, polishing or a finishing passAdds a process step, not just machining time

Common Applications

  • gears
  • Aeronautical Industry
  • transportation industry

Process Options

  • CNC machining is a subtractive manufacturing process.
  • Finishing Options: Black Oxide, Electropolishing, ENP, Media Blasting, Nickel Plating, Passivation, Powder Coating, Tumble Polishing, Zinc Plating, Vibratory Tumbling
  • EPX 82 is processed using Carbon DLS
  • MUD is a type of mold that uses a standard injection molding frame.
  • Different taper turning methods suit different jobs. Compound slides often handle short tapers, while CNC interpolation and taper attachments improve repeatability on longer parts
  • G92 is used by programming one or more G92's right after the G76 threading cycle
  • Estimates are provided through an auto-quoted method.
  • EDM relies on a voltage and a thin wire
  • Advanced machining processes like micro-machining and EDM are used to create small, precise mold cavities and cores

Surface Finish Reference

  • The finish of MoldTech MT11010 is a fine matte texture.
  • The finish of MoldTech MT11020 is a medium matte texture.
  • The finish of MoldTech MT11030 is a coarse matte texture.
  • SPI A-1 has a surface roughness of 0.012–0.025 µm.
  • SPI B-2 has a finish of Medium semi-gloss.
  • SPI B-2 has a surface roughness of 0.10–0.15 µm.
  • SPI C-3 has a surface roughness of 0.63–0.70 µm.
  • Super high gloss, polished with a Grade #3 (6000-grit) diamond buff to Ra 0.012–0.025 µm.
  • Medium semi-gloss, finished with 400-grit paper to Ra 0.10–0.15 µm.
  • Normal matte, polished with 320-grit stone to Ra 0.63–0.70 µm.

Tolerance Reference

  • The tolerance with drawing for CNC Milling is as low as +/- 0.005 mm.
  • FDM 3D printing offers a low-cost component with average accuracy and uses thermoplastics for 3D printing.
  • Wire Cut EDM is highly accurate.
  • The U6 H.E.A.T machine achieves tight tolerances.
  • Die sinker EDM is capable of maintaining tight tolerances
  • The shop needs to have CNC machines that can achieve a specific tolerance.

Industries We Serve

  • antennas
  • automotive
  • CNC machined parts
  • custom parts
  • electronics
  • medical diagnostic
  • optical displays
  • optical_systems

Material Reference

  • ABS
  • Austenitic Stainless Steel
  • Carbon steel
  • ceramic
  • composites
  • Copper - T2
  • copper or graphite
  • Hardened Materials
  • High Impact Polystyrene
  • Low-density polyethylene
  • MDF
  • metal
  • Polybutylene Terephthalate
  • SUS304
  • thermoplastics
  • thick metal sheets
  • tungsten carbide

Frequently asked questions

1018 or 1045 for my part?

1018 welds easily and suits general purpose work; 1045 suits shafts and wear parts needing strength and heat treatment. Send the load case and we recommend before quoting.

How do you control distortion after heat treatment?

We machine with stress relief and grinding allowance, and harden before final finishing where the design allows — critical tolerances are finished after heat treat, not before.

Is 12L14 acceptable under RoHS?

12L14 contains lead for machinability and is restricted in some applications. Where RoHS applies we machine 1018 or lead-free alternatives and flag the substitution in DFM review.

What is the minimum order quantity (MOQ)?

Prototypes from 1 pc. Low-volume production typical 50-500 pcs. No forced MOQ on custom parts; unit price drops with volume.

What is the typical lead time?

Industry benchmark: instant-quote platforms deliver prototypes in 1-3 business days. Our own production: prototypes 5-10 working days, including in-house QC and shipping. Production: 2-4 weeks depending on quantity/finishing. Express options exist; finishing adds days.

How do I get a quote and what information do you need?

3D files (STEP/IGS) + 2D drawing with tolerances. Material, quantity, finish, destination country. Quote turnaround: 24-48h typical.

What tolerance should I specify?

Specify tight tolerances only on critical features. Standard ±0.1 mm covers most features. Tighter tolerance = cost multiplier; apply selectively via drawing GD&T.

How is quality controlled?

First-article inspection in our own shop before the first production order. In-process checks. Final inspection report (dimensions) with shipment. Material certs (mill test reports) on request.

Is my design protected?

NDA before file exchange. Files used only for your production. No resale of custom designs.

Which material should I choose?

Function first: strength, weight, corrosion, cost. Common pairings: 6061 general, 304/316 corrosive env., PEEK medical. See materials guide pages.

Which surface finish do I need?

Anodizing for aluminum corrosion/wear/color. Passivation for stainless. Plating for conductivity/steel protection. Cosmetic vs functional distinction.

How do you ship and what terms?

DHL/FedEx/UPS express for samples and small batches. Air/sea freight for production volumes. Incoterms: EXW/FOB/DAP/DDP options.

Sources · 4

Technical references cited for verifiability — not supplier recommendations. Browse the research library.

Capability commitments on this page are owner-confirmed (2026-09-21).