Metals for CNC Machining —
Grades, Properties, Applications
We machine aluminum, steel, stainless, titanium, brass, copper, bronze, and tool steel — each in multiple grades optimized for different applications. Not sure which metal is right? Our engineers recommend the best option during your free DFM review.
The metal you choose determines how your part performs, how long it lasts, how much it costs to machine, and how much it costs to buy. Over-specifying wastes money. Under-specifying causes failures.
Match the Material to the Application
Two parts that look identical on a drawing can cost 3× different depending on the material. Aluminum 6061 machines in half the time of stainless 316 and costs a third as much per pound. But if your part lives in a saltwater environment, 6061 corrodes in months while 316 lasts decades.
The goal is matching the material to the application — not picking the most expensive option and not picking the cheapest. Not sure which metal is right? Upload your part and tell us your application. Our engineering team recommends the best material at no charge. → Engineering Support
Aluminum Alloys
The most commonly machined metal. Lightweight, corrosion-resistant, excellent machinability, available in dozens of alloys for different applications.
Aluminum 6061-T6
The DefaultThe default aluminum for CNC machining. If you are not sure which aluminum to specify, start here.
Aluminum 7075-T6
High StrengthUse when 6061 is not strong enough and steel is too heavy.
Aluminum 2024
Fatigue-RatedDeveloped for aircraft structures that see repeated loading cycles.
Aluminum 5052
Marine / SheetThe formability and corrosion champion. Best aluminum for sheet metal applications and marine environments.
Aluminum 6063
Best Anodize FinishMachines to a smoother finish than 6061 and anodizes with a more uniform appearance.
Steel Alloys
Strong, tough, heat-treatable, and available in hundreds of grades. Heavier than aluminum but significantly stronger.
Steel 1018 (Mild / Low Carbon)
Default Low-CostEasy to machine, easy to weld, readily available.
Steel 4140 (Alloy)
Heat-Treatable AlloyThe medium-carbon alloy steel for parts that need real strength.
Steel 4340 (Alloy)
Highest Strength Common SteelWhen 4140 is not enough.
Steel A36 (Structural)
Cheapest Common SteelLow-cost structural steel for non-precision parts.
Stainless Steel
Resists corrosion through chromium content. Different grades balance machinability, strength, and corrosion resistance differently.
Stainless 303
Fastest-Cutting StainlessAdded sulfur makes it the fastest-machining stainless grade.
Stainless 304
The Default StainlessThe most widely used stainless. The default when someone says "stainless steel."
Stainless 316
Corrosion ChampionWhen 304 is not enough.
Stainless 17-4PH
Strongest Common StainlessPrecipitation-hardened — heat-treat to high hardness while retaining corrosion resistance.
Stainless 440C
Hardest Common StainlessHardens to 58–60 HRC — comparable to tool steel.
Titanium
Highest strength-to-weight ratio of any structural metal. Biocompatible, corrosion-immune, and expensive.
Titanium Grade 2 (CP)
Commercially PureTitanium Grade 5 (Ti-6Al-4V)
The Workhorse AlloyThe most-used titanium alloy — 60% of all titanium production goes here.
Copper, Brass & Bronze
For electrical conductivity, thermal conductivity, fast turning, or self-lubricating bearings — this family covers them all.
Brass 360 (Free-Machining)
Fastest-Machining Common MetalThe fastest-machining common metal. Period.
Copper 101 (OFHC)
Conductivity ChampionThe electrical and thermal conductivity champion.
Copper 110 (ETP)
General ElectricalElectrolytic Tough Pitch — common, less expensive than 101.
Bronze 932 (SAE 660)
The Bearing MaterialTool Steel
Designed for making tools — dies, molds, punches, gauges. Machined annealed, then hardened, then finished by grinding or wire EDM.
D2
High wear resistance, air-hardening. The most common die steel. Best for: Blanking dies, forming dies, punches, slitter knives.
A2
Good toughness/wear balance, air-hardening. Less brittle than D2. Best for: Punches, dies, tooling where toughness matters.
H13
Hot-work steel, retains hardness at elevated temps. Best for: Die casting dies, extrusion tooling, hot forging dies, injection mold cores.
S7
Shock-resistant, highest impact toughness. Best for: Chisels, punches, shear blades, impact tooling. When the tool takes hits.
O1
Oil-hardening, fine grain, excellent dimensional stability. Best for: Gauges, jigs, fixtures, precision tooling, taps, reamers.
Metal Selection Guide
Cannot decide? Match your need to the recommended metal — or send us your part and we recommend at no charge.
Common Questions About CNC Machining Metals
What is the most commonly requested metal?
Aluminum 6061-T6 — approximately 40% of all CNC machining projects. It is the default choice when the application does not specifically demand something else.
Which metal is cheapest to machine?
Brass 360 and aluminum 6061 are the fastest and cheapest to machine. Steel 1018 is the cheapest steel option. Stainless 303 is the cheapest stainless option per cycle time.
Can you machine hardened steel?
Yes — via wire EDM. Conventional machining of hardened steel (above 45 HRC) destroys cutting tools. The typical approach: machine in annealed state → heat treat → finish critical features by EDM or grinding. → Wire EDM
Do you stock materials, or do we supply?
We source materials from verified suppliers with full material certifications (mill certs). You can also supply your own material — we machine what you send.
Can you provide material certifications?
Yes. Every shipment can include mill certifications showing chemical composition, mechanical properties, and heat lot traceability. Standard for aerospace, medical, and oil & gas projects.
Request a Quote
Tell us your material, quantity, and tolerances. If you are not sure which metal is right, tell us your application — our engineering team recommends the best option at no charge.
Mill certs available · Customer-supplied material accepted · sales@gpw-solutions.com