Material
Steel Machined Parts
Strong, hard-wearing, and the value pick when rust can be managed.
Steel is the strength-per-dollar choice for machined parts: mild grades for general structure, alloy grades like 4140 and 4340 that heat-treat to serious strength, and tool steels like A2, D2, and O1 for wear and cutting edges. The one real tradeoff is rust, and a finish like black oxide, zinc plating, or powder coat handles it. Send a STEP file and a PDF print through the quote form and a quote comes back in 24-48 hours.
Updated June 2026
Steel
Mild, alloy, and tool grades. The strength-per-dollar pick; it rusts bare, so plan on a finish or plating.
Why steel is the value pick
Pound for pound, steel is the cheapest way to buy strength. Mild steel stock costs less than aluminum and a fraction of stainless or titanium, and the alloy and tool grades deliver hardness and load capacity nothing lighter can match. When a part has to carry real force, take wear, or hold an edge, and weight is not the deciding factor, steel is usually the honest answer.
It also cuts predictably. Free-machining mild grades like 12L14 run fast and finish cleanly, which keeps machining time, the biggest line item in a custom part, down. The harder alloy and tool steels take more time, and that shows up in the quote, but you are paying for properties aluminum simply cannot reach.
Mild, alloy, and tool steel
Mild (low-carbon) steel like 1018 and A36 is the general-purpose group: weldable, inexpensive, and fine for brackets, plates, shafts, and weldments that do not need heat treatment. Free-machining 12L14 cuts and finishes even faster, but the lead and sulfur that let it cut so cleanly also make it weld poorly, so keep it to non-welded parts. Alloy steels like 4140 and 4340 are the workhorses for loaded parts, because they heat-treat to high strength and toughness for shafts, gears, axles, and fasteners that have to survive real stress.
Tool steels such as A2, D2, and O1 are bought for hardness and wear resistance: dies, punches, cutting edges, gauges, and fixture details that would wear out in anything softer. They are typically hardened after rough machining, and the hardest features are often finished by wire EDM or grinding rather than milling. If you are unsure which family fits, describe the load and wear in the notes and the grade gets settled before anything is priced.
What gets made from it
Steel turns up wherever strength and wear matter more than weight: shafts and axles, gears and sprockets, dies and punches, jigs and fixtures, structural brackets, bushings, and bearing components. Most of it is milled or turned, and it suits one-offs and small runs equally, with no minimum order.
Typical tolerances run ±0.005 in on milled features and ±0.001 in on critical turned diameters, held tighter where the print calls for it and where grinding finishes the job after heat treat.
Rust is the catch, and finishing handles it
Bare carbon steel rusts, so most steel parts get a finish. Black oxide adds mild corrosion resistance and a clean dark look, zinc and nickel plating step that up for harder service, and powder coat gives durable color. A film of oil protects parts in storage. For indoor fixtures and tooling, black oxide or a light oil is usually plenty.
If a part lives outdoors, in washdown, or anywhere continuously wet, fighting rust on carbon steel stops being worth it. That is the point to step up to stainless steel, which carries its corrosion resistance in the base metal instead of in a coating that eventually wears through.
Questions
Before you send a job.
01 Which steel should I pick: mild, alloy, or tool?
Mild steel (1018, A36) for general, weldable, budget parts, with free-machining 12L14 when machining speed matters and the part will not be welded. Alloy steel (4140, 4340) when it needs heat-treated strength, like shafts, gears, and high-load fasteners. Tool steel (A2, D2, O1) for hardness and wear, like dies, punches, and cutting edges. Describe the load and wear in the quote notes and the right grade gets flagged before pricing.
02 Does steel rust, and what stops it?
Bare carbon steel rusts, yes. Black oxide gives mild protection and a clean look, zinc or nickel plating and powder coat give more, and a film of oil protects parts in storage. If the part lives wet or outdoors all the time, stainless steel is usually the smarter buy than coating carbon steel and hoping the coating holds.
03 Can steel parts be heat-treated and hardened?
Yes. Alloy and tool steels are routinely hardened for strength and wear. Hardening can shift dimensions slightly, so tight features are often ground after heat treat, and very hard parts are cut by wire EDM instead of milled. Note the target hardness (a Rockwell range) on the print and it gets built into the plan.
04 Steel or aluminum?
Steel for strength, hardness, and wear at low material cost; aluminum when weight is the priority and the loads are moderate. Steel is roughly three times denser, so a steel part is heavy. If the part is strength- or wear-limited, steel wins; if it is weight-limited, aluminum does. Both quote the same way.
05 What tolerances can steel parts hold?
±0.005 in on milled features and ±0.001 in on critical turned diameters is routine, with tighter fits held on request and ground in after heat treat. Call out the critical dimensions on the print and the parts are inspected to them before they ship.
Get Started
Send us your files.
We’ll take it from there.
A quote in 24-48 hours, no minimums. Like the quote, and we’ll make your parts and ship them to you.
Get a Quote