6061 vs 7075 vs 316L: Spec the Alloy, Not the family

Aluminum is not a spec. Stainless is not a spec.

A 6061-T6 UAV motor mount and a 7075-T6 arrow nock do not machine the same, finish the same, or cost the same. A 303 pin and a 316L valve spool do not live in the same fluid. If the print says the family, the shop has to guess the grade.

Newtop cuts what the title block says. AL 6061 / 7075. SS 303 / 304 / 316L / 17-4PH. Brass. Titanium. POM/PC. Certs on request. Anodize, plating, passivation, heat treatment. Every lot measured. Reports in the box. Drawing to quote in one business day.

What should the material line say?

Alloy + temper + spec + finish + when the tolerance applies.

Write this:

AL 6061-T6, ASTM B221, Type II anodize black, dimensions AFTER finish

or this:

SS 316L, ASTM A276, passivate ASTM A967, sealing Ø inspected for Ra and roundness

Do not write “aluminum.” Do not write “SS.”

6061-T6 or 7075-T6?

6061-T6 is the default structural aluminum. Mounts, housings, numbered knobs. It machines clean. It takes Type II and Type III anodize. Call the temper. 6061 without T6 is incomplete.

7075-T6 is the strength-to-weight grade. Arrow nocks. Light parts that take shock. It does not weld like 6061. A vendor who ships 6061 against a 7075 print changed the design.

If mass matters, put max finished weight on the print. Hardcoat grows. Say whether size is before or after anodize.

UAV mounts: https://www.usanewtop.com/parts/uav-components

Arrow tips: https://www.usanewtop.com/parts/arrow-tips

303, 316L, or 17-4PH?

SS 303 is free-machining. Pins, points, fasteners, fittings. Use it when volume is high and corrosion is mild.

SS 304 when the print already says 304.

SS 316L for valve spools and stems, fluid, salt, and anything that gets wiped down. It work-hardens. Cycles are slower. That is the metal, not a bad quote. Do not substitute 303 onto a 316L print.

17-4PH after heat treat when you need stainless strength. Call the condition — H900, H1025. Call whether dimensions apply before or after heat treat. Plan the movement.

Valve spools and stems: https://www.usanewtop.com/components/valve-spools-stems

When is brass the right call?

Threads, seals, fittings, inserts. Newtop work in brass: tube insert with crown, hex transition nozzle fitting, corrugated bellow sealing stem, multi-flange pulley boss.

Titanium when the grade is the spec. POM / PC for insulator bodies and non-galling fits. If a metal part and a plastic part mate, send both prints on the same RFQ.

What does the finish do to size?

The cut sets the size. The finish sets wear, color, and corrosion.

Anodize grows. Plating grows. Passivation does not. Heat treat moves 17-4PH. Put the finish on the same PO as the cut, and say whether the tight diameters are before or after.

Inspection on this side: ZEISS CONTURA CMM, 0.9 μm. XRF alloy ID when the grade has to be proven. 300 kN tensile when the cert is not enough. Roundness. Roughness. Material certs on request.

What should a material RFQ include?

Send the PDF and the STEP.

1. Alloy and temper in the title block, not only in an email.
2. Spec if you have one — ASTM B221, A276, or the callout you already use.
3. Finish and whether size is before or after.
4. The two diameters that assemble. Not twelve.
5. Cert if the part is flight, fluid, or medical.
6. Quantity and the ship-to.

FAQ

Is “aluminum” enough on the drawing?

No. 6061-T6 and 7075-T6 differ in strength, weldability, and cost. The shop should not pick the grade.

Valve stem — 303 or 316L?

316L unless the environment is mild and volume is the driver.

Will Newtop substitute a cheaper grade?

Not against the print. If a cheaper grade would actually work, that is a quote conversation.

What alloys does Newtop machine?

SS 303/304/316L/17-4PH. AL 6061/7075. Brass. Titanium. POM/PC.

Where are you?

455 S 48th St, Suite 103, Tempe AZ 85281. annie@usanewtop.com.

Send the drawing, the alloy, and the finish.

https://www.usanewtop.com/rfq

— Newtop Group

Precision CNC machining. Custom metal parts, machined properly.