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Materials for Audio Parts: What Each Alloy Does to the Finish
On a hi-fi part the alloy decides the anodize colour, the polish, how the edges hold and what the part costs to cut. This page lists the materials shops quote for audio parts, with the designations to write on the drawing.
Material table
Typical ranges, not promises. The shop that quotes you confirms what it can hold on your geometry and your finish. Equivalent designations are close, not identical, and on a cosmetic part the difference often shows.
| Material | Designations | Typical audio parts | Finish behaviour | Typical tolerance |
|---|---|---|---|---|
| Aluminum 6061-T6 | UNS A96061, EN AW-6061, JIS A6061 | Faceplates, knobs, platters, chassis plates | Clean Type II anodize, slightly greyer than 6063 | ±0.05 mm typical, ±0.02 mm on fits |
| Aluminum 6082-T6 | EN AW-6082 (no common UNS) | European plate and bar stock, same parts as 6061 | Anodizes close to 6061, not identical | As 6061 |
| Aluminum 6063-T5/T6 | UNS A96063, EN AW-6063 | Extruded chassis sides, heatsinks, trim profiles | Brightest, clearest anodize of the common alloys | ±0.1 mm on extruded sections |
| Aluminum 5052-H32 | UNS A95052, EN AW-5052, JIS A5052 | Folded covers, back panels, base plates | Anodizes to a different tone from 6000 series | ±0.2 mm on formed features |
| Aluminum 7075-T6 | UNS A97075, EN AW-7075 | Tonearm parts, headshells, high stress small parts | Anodizes with a yellow or brown cast, poor for colour match | ±0.02 to ±0.05 mm typical |
| Brass C360 | UNS C36000, EN CW603N, JIS C3604 | Knobs, feet, terminals, trim rings, counterweights | Polishes and plates well, tarnishes bare | ±0.05 mm typical |
| Copper C110 / C145 | UNS C11000 / C14500, EN CW004A | Trim, busbars, heat spreaders, platter inlays | Lacquer or plating needed, C145 machines far better | ±0.05 mm typical |
| Stainless 303 / 304 / 316 | UNS S30300 / S30400 / S31600, EN 1.4305 / 1.4301 / 1.4401 | Spikes, feet, shafts, fasteners, wear faces | Brushed, bead blasted or polished, then passivated | ±0.05 mm typical |
| Titanium Grade 5 | UNS R56400, Ti-6Al-4V, EN 3.7165 | Headphone yokes, tonearm parts, premium knobs | Bead blast, polish, colour anodize, PVD | ±0.05 mm typical, slower and costlier to cut |
| Cold rolled steel | EN DC01, JIS SPCC, ASTM A1008 | Covers, transformer shrouds, internal brackets | Powder coat, zinc plating | ±0.2 mm on formed features |
| POM-C acetal | Polyoxymethylene copolymer | Platters, mats, bushings, insulators, knob inserts | Machined finish only, does not paint or bond well | ±0.1 mm, moves with temperature |
| Acrylic and polycarbonate | PMMA, PC | Display windows, dust covers, light pipes, platters | Flame or vapour polished edges, scratch-prone | ±0.1 mm, moves with temperature |
Background on the designation system: aluminium alloy. Short definitions of 6061-T6, 6063-T5, C360 brass and temper are in the glossary.
Choosing by what the part has to do
Most audio parts are chosen for one dominant property. Start there, then check the finish.
- Look and colour match6061 or 6063 aluminum, one alloy per assembly where possible. Avoid 7075 and 2000 series on anything that must match. Alloys for anodized audio parts
- Mass and inertiaBrass (about 8.5 g/cm³) and stainless (about 8.0 g/cm³) add mass to platters, feet and counterweights. Aluminum is about 2.7 g/cm³, POM about 1.4 g/cm³.
- Stiffness to weightAluminum, titanium and carbon fibre tube for tonearms and headphone yokes, where low mass and high stiffness both matter. Tonearm tube materials
- HeatCopper conducts about twice as well as 6063, which conducts better than 6061. Extruded 6063 is the default heatsink, copper is used where heat is concentrated. Copper heatsinks and busbars
- Wear and hardnessStainless for spikes, cones and shafts. Hard anodize on aluminum for bearing faces that do not need to match a colour.
- Touch and tarnishBrass and copper feel heavy and warm but tarnish bare. Plan lacquer or plating from the start. Brass and copper parts
- Insulation and dampingPOM, nylon and acrylic for insulators, mats, windows and light pipes. Plastics move with temperature, so loosen tolerances. Acetal and nylon parts
Material lines to put on the drawing
A material note that only says "aluminum" gets three different alloys quoted. These lines make quotes comparable and keep a repeat order looking like the first.
For stainless choices on knobs and feet, see 303 vs 304 stainless. For titanium cost, see titanium audio parts.
- Alloy and temper6061-T6, not "aluminum". C360 half hard, not "brass".
- Stock formPlate, bar, extrusion or sheet, because each finishes differently.
- Mill lotOne lot per order for colour critical parts, and a retained sample.
- CertificateMill certificate with the order, so the alloy can be traced.
- SubstitutesWhich equivalents you accept, if any.
- Market rulesRoHS, REACH or Proposition 65 limits that affect leaded brass and coatings.
Questions about materials
Why do my 6061 faceplate and 6063 chassis sides anodize to different shades?
The alloys contain different amounts of silicon, magnesium and copper, and those elements change how the oxide forms and takes dye. 6063 anodizes clearer and brighter, 6061 slightly greyer, 5052 different again. Bead blasting both parts before anodizing narrows the gap, and an approved sample from the real alloys is the only reliable check.
Is C360 brass a problem for RoHS or Proposition 65?
C360 contains about 3 percent lead. RoHS currently allows lead in copper alloys up to 4 percent under an exemption, and California Proposition 65 can require a warning label for parts a user handles. Check the rules for your market and the date of any exemption renewal. Low lead brasses such as C69300 or CW724R are the usual alternative and cost more to machine.
Which material is best for a turntable platter?
There is no single answer. Aluminum 6061 is light, stiff and easy to balance. Brass and stainless add mass and rotational inertia but cost more to cut and finish. POM and acrylic damp ringing and are often used as a top layer. Specify flatness, runout and balance on the drawing whichever you choose.
Can a shop substitute an equivalent alloy?
Only if you say so. Equivalents such as 6061 and 6082 are close in strength but not in anodize colour, which is the specification on a cosmetic part. Write the alloy and temper on the drawing, accept "or equivalent" only where appearance does not matter and ask for a mill certificate. We match the RFQ with up to 3 shops that stock or can buy your alloy.
Know the alloy? Send the drawing.
We match it with up to 3 shops that machine and finish parts in that material, and reply within 24 business hours. How parts are made: processes. Which part gets what: applications.