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MACHINING DATA · M AUSTENITIC STAINLESS (FREE-CUTTING)

AISI 303 machining data: cutting speed, feed and carbide grade to start with.

Starting cutting speed in m/min and sfm, feed in mm/rev and ipr, the carbide grade class and the setup by operation for AISI 303 (X8CrNiS18-9). The numbers are the published M01 Austenitic (304, 316L) sub-group starting band; the designations are on the cross-reference page.

ISO M · Stainless steel M01 sub-group m/min + sfm · mm/rev + ipr Free, no signup

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01 · AT A GLANCE

AISI 303: group, sub-group and condition

ItemValue
ISO 513 groupM Stainless steel
Sub-groupM01 Austenitic (304, 316L)
Sub-group hardness / condition150–220 HB
CategoryAustenitic stainless (free-cutting)
EN / WerkstoffnummerX8CrNiS18-9 · 1.4305

Hardness is the range published for the whole M01 Austenitic (304, 316L) sub-group on our material guide; the delivery condition of your AISI 303 may sit anywhere inside it or outside it.

02 · STARTING CUTTING DATA

Cutting speed and feed for AISI 303

ConditionVc m/minVc sfmFeed mm/revFeed ipr
M01 Austenitic (304, 316L), 150–220 HB120–200395–6550.10–0.35.004–.014

Sub-group starting values for carbide inserts, from M01 Austenitic (304, 316L). They describe the whole sub-group and are not tuned to AISI 303. sfm and ipr are converted from the metric values (1 m/min = 3.281 sfm, 25.4 mm = 1 in). The published band is per sub-group, not per operation; the table below gives the setup by operation. Convert Vc to spindle speed with the speeds & feeds calculator, and see the speeds & feeds guide for the ISO M group range.

Setup by operation

OperationGeometryCoating familyCoolantFirst check
RoughingPositive rake, lightly honed edge, open polished chipbreaker; avoid a heavy negative landTough PVD-coated carbideHigh-pressure coolant 15–20 bar aimed at the edgeConsistent depth of cut: stay above the work-hardened layer
FinishingPositive rake, sharp edge, polished chipbreakerPVD-coated carbide, sharper edgeHigh-pressure coolant 15–20 barBuilt-up edge: Vc too low or tool dwelling
Interrupted cutPositive but robust honed edgeTougher PVD-coated carbideHigh-pressure coolant 15–20 barNotch wear at the depth-of-cut line: vary DOC between passes
Low rigidity / thin wallPositive rake, sharp edge to avoid pushing the materialPVD-coated carbideHigh-pressure coolant 15–20 barFeed high enough for the chipbreaker to engage

Setup rows are the selection table of the M01 Austenitic (304, 316L) guide. They carry no speeds, so they do not change the starting band above.

Same sub-group, same starting band: AISI 304 · AISI 304L · AISI 316 · AISI 316L · AISI 316Ti · AISI 321

03 · CARBIDE GRADES

Carbide grade class for AISI 303

Tough PVD-coated carbide. Roughing ≈ M25–M30 for heat and edge security; finishing ≈ M10–M20 for a sharper edge and better surface.

The P, M, K, N, S or H number inside a grade range describes what the grade is built for, not the workpiece sub-group number, and the two scales must not be matched to each other. We name no single grade here: none of our published sources ties a named grade to this alloy. Pick by ISO class, then compare what the makers publish on the ISO M grade list and in the grade chart.

04 · DESIGNATIONS

AISI 303 in EN, US and JIS terms

EN X8CrNiS18-9, Werkstoffnummer 1.4305, US AISI 303 (UNS S30300), JIS SUS303. The full table, with the nearest-match flags, is on the AISI 303 / 1.4305 cross-reference page.

05 · NOTES

How X8CrNiS18-9 behaves in the cut

The free-machining austenitic: sulphur breaks the chips 304 will not. Runs faster and cleaner than 304 at the cost of corrosion resistance and weldability on the part.

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06 · FAQ

Common questions

What cutting speed should I start with for AISI 303?

The published starting band for the M01 Austenitic (304, 316L) sub-group is 120–200 m/min (395–655 sfm) at 0.10–0.35 mm/rev (.004–.014 ipr). It is a starting band for the whole sub-group, not a value tuned to AISI 303, so confirm on a sample part and adjust for condition, tool and rigidity.

Which carbide grade should I use for AISI 303?

Tough PVD-coated carbide. Roughing ≈ M25–M30 for heat and edge security; finishing ≈ M10–M20 for a sharper edge and better surface. Pick the grade by ISO class rather than by brand name, then confirm the exact grade for your condition. We name no single grade here because none of our published sources ties a named grade to this alloy.

What is AISI 303 called in EN, US and JIS standards?

EN X8CrNiS18-9 (Werkstoffnummer 1.4305); US: AISI 303 (UNS S30300); JIS: SUS303. Entries marked nearest are the closest commonly-cited counterpart, not a same-composition equivalent.

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Starting band found. Now the exact grade.

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