Knowledge Base

Material Selection Guide

Writing "aluminum" instead of "6061-T6" on a drawing can change the quote several times over. Material decides three things: can it be machined, how long it takes, and what it costs. This is our shop-floor notes — which materials cut easy, which cost more and why, and what to pick for what job.

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At a glance

Seven Common Materials

"Relative cost" is benchmarked at 1× for aluminum 6061-T6 and already folds in tool wear, cycle time and scrap rate. These are long-run shop experience ranges, not absolute values.

Material	Cutting speed (ref.)	Tool life	Surface finish	Relative cost
Aluminum 6061-T6	Fast (300–500 m/min)	Long	Good (Ra 0.8 easy)	1×
Aluminum 7075-T6	Quite fast (250–400 m/min)	Medium	Good	1.2×
Brass C360	Very fast (400–600 m/min)	Very long	Excellent	1.1×
Stainless 304	Slow (80–150 m/min)	Short (work-hardens)	Poor (multi-pass)	3–4×
Stainless 316L	Very slow (60–120 m/min)	Very short	Poor	4–5×
Titanium Ti-6Al-4V	Very slow (30–60 m/min)	Very short (burns/chips)	Medium	5–8×
PEEK (eng. plastic)	Medium (200–300 m/min)	Medium	Good	1.5×

Carbon steel (e.g. 45#, Q235) is also common — cheaper than stainless but it rusts. Avoid for outdoor or humid use unless you add a coating.

Material by material

Straight Talk

Aluminum 6061-T6 — the value king, pick it by default. For most structural parts, enclosures and brackets, 6061-T6 is enough. Cuts fast, easy on tools, nice surface — Ra 0.8 comes easy. If the function allows, this is our first recommendation.

Aluminum 7075-T6 — high strength, but tougher to chew than 6061. 7075 is far stronger than 6061, used in high-reliability and load-bearing parts. But it's gummier, builds up edge, and wears tools faster — the 1.2× is just material delta; real cost is a bit higher once you count machining. Not unusable, just "expensive for a reason."

Brass C360 — the free-machining champion. Cuts blazing fast, tools last forever, surface comes out bright. Great for precision small parts, fittings, decorative pieces. Only slightly above aluminum in cost, but the look is much better.

Stainless 304 / 316L — corrosion resistant, but "slow" is the killer. The real enemy is work hardening: a dull tool hardens it, and it gets harder the more you cut. You must run sharp fresh tools at high enough speed. So short tool life and long cycle time are normal. Two notes: ① lead time runs 30–50% longer than aluminum; ② loosen the tolerance one notch, and Ra 1.6 is the sane ceiling — don't insist on Ra 0.8. 316L resists chlorides better (coastal, chemical) but is slower and pricier.

Titanium Ti-6Al-4V — only if you must. Titanium's machining cost eats the margin: very slow, tools chip easily, and it burns. Reserved for biocompatible / high-temp parts. If 316L or 7075 can do the job functionally, switch — the savings are not small.

PEEK — for high-temp / insulating jobs only. PEEK handles heat, insulates, self-lubricates — the go-to for semiconductor and medical. Around 1.5× in cost, not slow to cut, but watch workholding (it lets go and deflects). For non-high-temp needs, plain nylon or ABS is far cheaper.

Quick lookup

What to Pick for What

Your need	First pick	Note
General structure, enclosure, bracket	6061-T6	Best value
Load-bearing, high-reliability / high strength	7075-T6	Accept slightly higher cost
Precision small parts, brass fittings, decorative	Brass C360	Bright finish, easy cut
Food / medical / coastal / chemical corrosion	304 / 316L	+30–50% lead time, looser tol.
Biocompatible / high temp	Titanium	Only if functionally required
High-temp insulation / semiconductor	PEEK	Use nylon/ABS if not needed
Indoor dry structure, want to save	Carbon steel + coating	Rusts; rely on plating

Old-hand reminders

Save Half Your Rework

Write the full grade, not the family. "Aluminum" ≠ "6061-T6"; "stainless" ≠ "304". Just write the grade — 6061-T6, 304 SS, 7075 — and we're done in one step.
No verbal "material guarantee." Every order ships with a material cert (MTC, heat-number traceable) — a real factory's floor, and what you should ask for when auditing a supplier.
Avoid recycled aluminum for critical parts. Cheap recycled bar carries more impurities and internal stress — easy to warp, strength unstable. Use prime billet for key parts.
Want to resist rust and save money? Use a coating. Carbon steel powder-coated / zinc-plated, or anodized aluminum, is often cheaper than going straight stainless and reaches similar corrosion resistance.
No material on the drawing? Tick "as per drawing" or type the grade. In our RFQ form, material defaults to "as per drawing" — we follow what your drawing says; to switch or specify, just type one line.

One line to remember: if the function allows, pick 6061-T6; for corrosion resistance pick 304; for strength pick 7075; save titanium and PEEK for when they're truly needed.

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