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MaterialsMaterials for CNC machined parts, grade by grade
These are the metals and plastics the shops in our network cut, with the equivalents your drawing may use and how fast each one can be in a machine. The shop we introduce you to buys the material, and the grade on its quote is the grade on your parts.
Six families, the grades that ship most
Machinability is relative within the whole list, from excellent (brass, free cutting aluminium) to poor (hardened tool steel, Ti-6Al-4V). The band is where the material usually comes from: stocked locally, available with notice or imported to order. Equivalents overlap closely and are not identical, so the standard on your drawing decides.
Aluminium
The default for brackets, housings, plates and fixtures. Fast to cut, light and easy to anodise, so it is the cheapest metal part you can buy here.
| Grade | Equivalents | What it suits | Machinability | Band |
|---|---|---|---|---|
| 6061-T6 / T651 | UNS A96061 · EN AW-6061 · JIS A6061 | General structural parts, housings, fixtures. Welds and anodises well. | Excellent | Stocked |
| 6063-T5 / T6 | UNS A96063 · EN AW-6063 · JIS A6063 | Extruded profiles and cosmetic parts that need an even anodise. | Good | Stocked |
| 7075-T6 / T651 | UNS A97075 · EN AW-7075 · JIS A7075 | High strength parts under load. Poor weldability, anodise colour differs from 6061. | Excellent | With notice |
| 5083-H111 / H321 | UNS A95083 · EN AW-5083 · JIS A5083 | Marine and vacuum plate. Not heat treatable, gummy to cut, good corrosion resistance. | Fair | Checked on the quote |
Stainless steel
Chosen for corrosion resistance or hygiene, paid for in machining time. It work hardens and holds heat, so the same geometry costs several times what it costs in aluminium.
| Grade | Equivalents | What it suits | Machinability | Band |
|---|---|---|---|---|
| 303 | UNS S30300 · EN 1.4305 · JIS SUS303 | Turned parts at volume. Sulphur added for chip breaking, lower corrosion resistance, poor weldability. | Good | With notice |
| 304 / 304L | UNS S30400 / S30403 · EN 1.4301 / 1.4307 · JIS SUS304 / SUS304L | General purpose stainless for indoor and food contact parts. L grade for welded parts. | Fair | Stocked |
| 316 / 316L | UNS S31600 / S31603 · EN 1.4401 / 1.4404 · JIS SUS316 / SUS316L | Chlorides, marine and chemical exposure. Molybdenum makes it tougher to cut than 304. | Fair | Stocked |
| 416 | UNS S41600 · EN 1.4005 · JIS SUS416 | Free machining martensitic grade. Magnetic and hardenable, modest corrosion resistance. | Good | With notice |
| 17-4 PH | UNS S17400 · EN 1.4542 · JIS SUS630 | High strength with fair corrosion resistance. State the condition: H900, H1025 or H1150. | Fair | With notice |
Carbon, alloy and tool steel
Local stock is sold under JIS names, so a drawing that says 1045 or C45 is usually cut from S45C. The overlap is close, and the shop states the grade it will buy on its quote.
| Grade | Equivalents | What it suits | Machinability | Band |
|---|---|---|---|---|
| S45C | AISI 1045 · UNS G10450 · EN C45 (1.0503) | Shafts, pins, gears and general machine parts. Induction hardens. | Good | Stocked |
| S50C | AISI 1050 · UNS G10500 · EN C50 (1.0540) | Slightly harder wearing than S45C, for plates and guides. | Good | Stocked |
| SCM440 | AISI 4140 · UNS G41400 · EN 42CrMo4 (1.7225) | Highly loaded shafts and tooling parts. Bought pre-hardened or hardened after roughing. | Fair | Stocked |
| SS400 | JIS G3101 · close to ASTM A36 and EN S275JR | Base plates, frames and weldments where strength is not critical. | Good | Stocked |
| SKD11 | AISI D2 · UNS T30402 · EN 1.2379 | Cold work dies, punches and wear parts. Hardened features finished by grinding or EDM. | Poor | With notice |
| SKD61 | AISI H13 · UNS T20813 · EN 1.2344 | Hot work tooling, die casting inserts, parts that run hot. | Fair | With notice |
Copper and brass
Brass is the easiest metal in the list to machine and leaves the best surface. Copper is chosen for conductivity and is soft enough to burr on every edge.
| Grade | Equivalents | What it suits | Machinability | Band |
|---|---|---|---|---|
| C3604 brass | JIS H3250 · close to UNS C36000 and EN CW614N | Fittings, connectors, turned parts at volume. Contains lead, so state any lead limit. | Excellent | Stocked |
| C1100 copper | UNS C11000 · EN Cu-ETP (CW004A) · JIS C1100 | Busbars, electrodes, heat spreaders. Needs sharp tools and careful deburring. | Fair | Stocked |
Titanium
Slow to cut and hard on tools, so quantity moves the unit price more than it does in any other metal here.
| Grade | Equivalents | What it suits | Machinability | Band |
|---|---|---|---|---|
| Grade 2 | UNS R50400 · EN 3.7035 · JIS H4600 class 2 | Commercially pure. Corrosion resistance first, strength second. | Fair | With notice |
| Grade 5 (Ti-6Al-4V) | UNS R56400 · EN 3.7165 · JIS H4600 class 60 | Strength to weight. Industrial parts only, not implant grade. | Poor | With notice |
Engineering plastics
Cheap to cut and expensive to hold. Plastics move with heat and moisture, so tolerances that are routine in metal need a conversation here.
| Grade | Equivalents | What it suits | Machinability | Band |
|---|---|---|---|---|
| POM (acetal) | ASTM D6100 · homopolymer or copolymer | Gears, bushings, wear strips and precision plastic parts. The most stable of the common plastics. | Excellent | Stocked |
| Nylon PA6 / PA66 | ASTM D6779 | Tough wear parts and rollers. Absorbs water and grows with it. | Good | Stocked |
| HDPE, PC, acrylic | Commodity sheet and rod | Guards, covers, chemical tanks, light pipes and display parts. | Good | Stocked |
| PTFE | ASTM D3294 | Seals, low friction and chemical contact. Creeps under load. | Good | With notice |
| PEEK | ASTM D8033 | High temperature and chemical resistance. Imported to order, priced per kilogram like a metal. | Good | Imported |
Designations follow the Unified Numbering System and the EN and JIS material standards. Lead time per band, and what moves it: material availability in Vietnam. Processes and tolerances for each family: capabilities.
Pick the cheapest grade that does the job
Most drawings over-specify material by habit. Start from the property the part needs and move up only when the cheaper grade fails it.
- Light and stiff enough6061-T6. Move to 7075 only when a calculation says 6061 is not strong enough, because 7075 costs more, welds badly and anodises a different shade.
- Rust free indoors304, or anodised aluminium. 303 when the part is turned at volume and will not be welded.
- Salt, chlorides or chemicals316 or 316L, passivated. Titanium Grade 2 when 316 is not enough, and the price is worth it.
- Wear and loadS45C induction hardened, or SCM440 pre-hardened. SKD11 when the surface takes repeated impact or abrasion.
- Electrical or thermal pathC1100 copper for conductivity, 6061 or 6063 aluminium when weight matters more than the last few percent.
- Low friction or insulationPOM first, nylon when toughness matters more than stability, PTFE for chemicals and sliding, PEEK only when heat rules out the others.
How material is handled on your order
You buy the parts from the shop, directly, so the material is part of what you agree with the shop. We check the grade when we review your drawing, before it goes to a shop. If you want it, we also follow the order and inspect the parts before they ship, with the scope agreed per project.
More on how quality is checked: quality. The order end to end: how it works.
- Grade checked in the drawing reviewBefore your drawing goes to a shop we check the grade, the temper or condition and the standard against what is stocked locally. If the stocked equivalent is a JIS grade, we say so before you see a quote.
- Grade confirmed on the shop quoteThe shop names the grade and the standard it will buy to. Approve it before you place the order, and write it on the purchase order.
- Material lead time on its own lineWhen the material is not on the shelf, ask the shop to quote its lead time separately from the machining, so you can see what the date is waiting for.
- No silent substitutionOnce you approve a grade, the shop cuts that grade. Agree with the shop that any change after the purchase order comes back to you in writing first.
- Certificates when you askA mill certificate traceable to the heat is agreed with the shop when you request it. Say so at the start, because certified material is usually ordered rather than taken from stock.
Material choices that take money off the part
- Design to standard stockPlate and bar come in standard thicknesses and diameters. A part that needs 47 mm stock waits for 47 mm stock or is cut from 50 mm and costs the difference.
- Name the condition, not only the grade6061 means little without T6 or T651. 17-4 PH means little without H900 or H1150. The condition decides strength, stability and what the shop buys.
- Say which property mattersOne line such as "corrosion in sea air" or "must not be magnetic" lets the shop offer a cheaper grade that still does the job, or tells it not to.
- Put the finish next to the materialAnodise colour varies between alloys, passivation is part of buying stainless, and plating thickness changes fits. Material and finish are quoted together.
- Avoid brand names for generic plasticsCalling for one maker of POM or PEEK can add weeks for no functional gain. Specify the polymer and the standard unless the brand is a real requirement.
Background on property data: ASM International publishes the reference handbooks most material tables, including this one, trace back to.
Material guides, one family at a time
Carbon and alloy steels for machined parts: 1045, 4140 and 4340 compared
How 1045, 4140 and 4340 differ in strength, hardenability and machinability, which condition to buy, how to protect them from rust and what to write in an RFQ.
MaterialsBrass and copper grades for machined parts: C360, C260, C464 and C110 compared
How common brass and copper grades differ in machinability, conductivity and corrosion, what lead means for compliance, and how to name the grade in an RFQ.
MaterialsChoosing an aluminium grade: 6061, 6063, 7075 and the tempers that matter
What separates the common machining aluminium grades in strength, machinability, corrosion resistance and finish, and which ones are on the shelf in Vietnam.
MaterialsChoosing a stainless grade: 303, 304, 316 and 17-4 PH
How the common stainless grades differ in machinability, corrosion resistance and strength, what each one does to your machining cost and which are stocked in Vietnam.
MaterialsMachining plastics: what POM, nylon, PTFE and PEEK do differently
Engineering plastics machine fast and move afterwards. What to expect on tolerance, moisture, stress relief and cost, and how to specify a plastic part that comes back right.
MaterialsWhen a shop offers a different material, how to answer
Equivalent grades, local stock and certified heats. How to tell a sensible substitution from a quiet downgrade, and what to write in the request so it never becomes a dispute.
About materials
Which materials does the network machine most often?
Aluminium 6061, stainless 304 and 316, S45C carbon steel, brass and POM. They are held in local stock, so on those grades the schedule is a machining schedule with no material wait inside it. Titanium, 7075, 17-4 PH and the tool steels come with notice.
My drawing calls for an ASTM or EN grade. Will the shop buy that exact grade?
Where it is stocked, yes. Where the local stock is the JIS equivalent, such as S45C for 1045 or SUS304 for 1.4301, the shop quote names the equivalent and you decide. If the drawing says no substitution, the shop buys the specified grade and quotes the extra lead time.
Do the parts ship with a material certificate?
When you ask for one. Put it in your request and agree it with the shop before the order, because traceable material is usually ordered rather than taken from stock. The inspection report that ships with the parts is agreed with the shop in the same way.
Can you supply PEEK or other imported materials?
Yes. PEEK and other high performance polymers are imported to order, which typically adds three to six weeks before cutting starts. Ask for the material lead time on its own line in the shop quote so you can decide whether the date works.