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Swiss Machining Materials and Bar Stock
Which bar materials run well on a Swiss-type lathe, how each one changes cycle time and tolerance, and what bar quality the guide bushing needs.
We are a matching service and own no machines. Figures on this page are typical ranges. The shop that quotes you confirms what it can hold on your material and geometry.
Grades at a glance
Common bar grades for small turned parts, with the designations you may see on a drawing in the US, Europe and Japan. Equivalents are close, not identical: the standard on your drawing governs.
| Grade | UNS | EN | JIS | Machinability on a Swiss lathe |
|---|---|---|---|---|
| 12L14 (leaded free-machining steel) | G12144 | 11SMnPb30 (1.0718) | SUM24L | Excellent. Fast cycles, short chips |
| 1215 (resulfurized free-machining steel) | G12150 | 11SMn30 (1.0715) | - | Very good. Lead-free option |
| 303 stainless | S30300 | X8CrNiS18-9 (1.4305) | SUS303 | Good. The free-machining stainless |
| 304 / 316L stainless | S30400 / S31603 | 1.4301 / 1.4404 | SUS304 / SUS316L | Fair. Work hardens, stringy chips |
| 416 stainless | S41600 | X12CrS13 (1.4005) | SUS416 | Good. Magnetic, hardenable |
| 17-4 PH stainless | S17400 | X5CrNiCuNb16-4 (1.4542) | SUS630 | Fair. Usually cut in condition A, then aged |
| Free-cutting brass | C36000 | CuZn36Pb3 (CW603N) | C3604 | Excellent. Fastest of all metals |
| Lead-free brass | C69300 | CuZn21Si3P (CW724R) | - | Good. Longer chips than C36000 |
| Aluminum 2011-T3 | A92011 | EN AW-2011 | A2011 | Excellent. Free-machining aluminum |
| Aluminum 6061-T6 / 7075-T6 | A96061 / A97075 | EN AW-6061 / 7075 | A6061 / A7075 | Good. Needs chip control on long parts |
| Titanium Grade 5 / Grade 23 | R56400 / R56401 | 3.7165 / - | - | Fair. Slow speeds, sharp tools, high-pressure coolant |
Material by material
What each family is used for on Swiss-type work and what it does to price.
Free-machining steels
12L14 and 1215 make pins, shafts, fittings and screws that will be plated or blackened. Lead and sulfur break chips and extend tool life. 12L14 is a poor choice for welded parts and for parts that must be lead-free. Free-machining steel guide.
Stainless steels
303 for volume parts where corrosion is mild, 304 and 316L for fluid, food and medical parts, 416 and 17-4 PH where hardness is needed. Austenitic grades work harden, so tools stay sharp and feeds stay constant. Passivation is the usual finish. Stainless guide.
Brass and copper alloys
C36000 is the default for connector bodies, inserts and fittings. Lead-free brasses cover drinking water and RoHS parts. Tellurium copper, beryllium copper and phosphor bronze are used for contacts and springs. Brass guide.
Aluminum
2011 cuts cleanly at high volume. 6061 and 7075 are stronger but form long chips that wrap on slender parts, so chip control decides the cycle. Anodize adds thickness to diameters. Aluminum guide.
Titanium
Grade 5 and Grade 23 (ELI, ASTM F136) for bone screws, dental parts and lightweight pins. Poor heat conduction keeps heat at the edge, so surface speeds are low and tools wear fast. Expect a higher price per part than stainless. Titanium guide.
Engineering plastics
PEEK, POM (acetal), PEI and PTFE turn well but flex under the tool and move with heat and moisture. Around ±0.025 mm is realistic on diameters. Sharp, polished tools and support near the cut matter more than speed. PEEK guide.
Typical tolerance by material
Diameter tolerance a Swiss shop typically holds by turning alone, before grinding. Long, thin features and hard materials move toward the looser end.
| Material | Typical diameter tolerance | Typical as-turned finish | Relative cycle time |
|---|---|---|---|
| Brass C36000 | ±0.005 to ±0.01 mm | Ra 0.4 to 0.8 µm | Fastest |
| 12L14 / 1215 | ±0.005 to ±0.01 mm | Ra 0.4 to 0.8 µm | Fast |
| 303 / 416 stainless | ±0.005 to ±0.013 mm | Ra 0.4 to 0.8 µm | Medium |
| 304 / 316L / 17-4 PH | ±0.005 to ±0.013 mm | Ra 0.8 µm | Medium to slow |
| Aluminum 2011 / 6061 / 7075 | ±0.008 to ±0.013 mm | Ra 0.4 to 0.8 µm | Fast |
| Titanium Grade 5 / 23 | ±0.008 to ±0.013 mm | Ra 0.8 µm | Slow |
| PEEK / POM | about ±0.025 mm | Ra 0.8 µm | Medium |
For more, see the guides on tolerances and surface finish.
Bar stock tolerances
A guide bushing supports the bar right next to the cut, so it is set with very little clearance. If the bar varies in size or is not straight, the part can chatter, show feed marks or drift in size along its length. That is why many Swiss shops buy precision ground bar. Bar tolerance classes come from ISO 286; the values below are the standard limits for a shaft (h) tolerance.
| Bar diameter | h6 | h7 | h8 | h9 | h11 |
|---|---|---|---|---|---|
| over 3 to 6 mm | 0 / -0.008 | 0 / -0.012 | 0 / -0.018 | 0 / -0.030 | 0 / -0.075 |
| over 6 to 10 mm | 0 / -0.009 | 0 / -0.015 | 0 / -0.022 | 0 / -0.036 | 0 / -0.090 |
| over 10 to 18 mm | 0 / -0.011 | 0 / -0.018 | 0 / -0.027 | 0 / -0.043 | 0 / -0.110 |
| over 18 to 30 mm | 0 / -0.013 | 0 / -0.021 | 0 / -0.033 | 0 / -0.052 | 0 / -0.130 |
Ground bar, about h6 to h8
Typical for guide bushing work on tight diameters and long parts. Costs more per meter but runs with fewer stops and less scrap. Ground bar guide.
Drawn bar, about h9 to h11
Cold drawn bar is cheaper and works in guide bushing-less mode, on short parts or where diameters are not tight. The shop may turn the bar down first.
Straightness and length
Bar feeders usually take bars around 3 to 3.7 m long. Bent bar whips in the feeder at high speed. Ask what straightness the shop buys to if the part is long and thin.
Background: engineering fits and ISO 286 tolerance classes and machinability.
Choosing a material for a Swiss part
Start with what the part has to do, then pick the most machinable grade that does it. A few rules of thumb:
- Mild corrosion, high volume: 303 stainless or C36000 brass usually beats 316L on price.
- Plated or blackened steel parts: 12L14 or 1215 run faster than 1018 or 1045.
- Body contact or seawater: 316L or titanium. Name the standard, for example ASTM F138 or ASTM F136.
- Hardness after machining: 416 or 17-4 PH. Say whether dimensions apply before or after heat treatment.
- Drinking water or RoHS: lead-free brass or unleaded steel. State the rule on the drawing.
- Electrical insulation or low weight: PEEK, PEI or POM, with tolerances opened up to about ±0.025 mm.
What to put on the RFQ
Grade and standard, temper or condition, whether you need mill certificates traceable to heat number, any RoHS or REACH requirement and your yearly volume. Bar size matters too: a part designed just over a common bar diameter forces a larger bar and more scrap per part. The materials guide covers more grades, and capabilities shows the machine layouts and size range. See applications for the parts these materials usually become.
Questions about Swiss machining materials
Do I need ground bar for Swiss machining?
For guide bushing work on tight diameters, usually yes. The guide bushing is set close to the bar, so diameter variation and poor straightness cause chatter, marks and size drift. Precision ground bar in about h6 to h8 is common. Cold drawn bar in h9 to h11 can work in guide bushing-less mode or on looser parts. The shop that quotes you says which it plans to use.
What is the easiest material to Swiss machine?
Free-cutting brass C36000 is the fastest, followed by leaded free-machining steel such as 12L14 and stainless 303. They break chips cleanly and give long tool life. If your part does not need the properties of 316L or titanium, a free-machining grade usually lowers the price per part.
Can a shop substitute an equivalent grade from another standard?
Only with your approval. EN, JIS and UNS equivalents are close but not identical in chemistry limits and test requirements. Write the grade and standard you need on the drawing and ask the shop to confirm in writing if it proposes an alternative.
Are lead-free brasses harder to machine?
Yes. Lead-free and low-lead brasses such as C69300 form longer chips and wear tools faster than C36000. They are needed where drinking water or RoHS rules apply. Expect a somewhat longer cycle time and say which rule applies in your RFQ.