Starting cutting speed in m/min and sfm, feed in mm/rev and ipr, the carbide grade class and the setup by operation for 20MnCr5 (W.-Nr. 1.7147). The numbers are the published P30 Case-hardened steel sub-group starting band; the designations are on the cross-reference page.
| Item | Value |
|---|---|
| ISO 513 group | P Steel |
| Sub-group | P30 Case-hardened steel |
| Sub-group hardness / condition | 58–62 HRC surface |
| Category | Case-hardening steel |
| EN / Werkstoffnummer | 20MnCr5 · 1.7147 |
Hardness is the range published for the whole P30 Case-hardened steel sub-group on our material guide; the delivery condition of your 20MnCr5 may sit anywhere inside it or outside it.
At least one designation of this material is a nearest commonly-cited counterpart, not a same-composition equivalent. The machining values below belong to the sub-group, so confirm the actual alloy and delivery condition on the material certificate.
| Condition | Vc m/min | Vc sfm | Feed mm/rev | Feed ipr |
|---|---|---|---|---|
| Soft state, carbide | 180–280 | 590–920 | see note | see note |
| Hardened case, CBN | 100–180 | 330–590 | 0.05–0.15 | .002–.006 |
Sub-group starting values for carbide inserts, from P30 Case-hardened steel. They describe the whole sub-group and are not tuned to 20MnCr5. The published feed for this sub-group is stated for the hardened-case (CBN) band only. 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 P group range.
| Operation | Geometry | Coating family | Coolant | First check |
|---|---|---|---|---|
| Roughing | Soft pre-carburized state: normal turning geometry | Soft state: P-class CVD carbide | Per process | Confirm before or after carburizing first; it changes everything |
| Finishing | Hardened case: negative with chamfer plus hone, rigid setup | CBN or hard ceramic on the 58–62 HRC case | Run as hard turning | White layer on the case: keep the edge fresh, speed in band |
| Interrupted cut | Chamfered honed edge, rigid setup | CBN with a robust grade | Run as hard turning | Case-to-core transition shock: favour edge security |
| Low rigidity / thin wall | Rigid setup, negative geometry with chamfer plus hone for the case | As state of the part | Per state | Edge chipping cutting the hard case |
Setup rows are the selection table of the P30 Case-hardened steel guide. They carry no speeds, so they do not change the starting band above.
Same sub-group, same starting band: 16MnCr5
Soft pre-carburized state: P-class CVD carbide. Hardened case (58–62 HRC): CBN or hard ceramic, like hard turning, with a honed/chamfered edge.
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 P grade list and in the grade chart.
EN 20MnCr5, Werkstoffnummer 1.7147, US AISI 5120 (nearest), JIS SCr420 (nearest). The full table, with the nearest-match flags, is on the 20MnCr5 / AISI 5120 cross-reference page.
Same story as 16MnCr5 with a touch more carbon. After case-hardening, the machining problem changes entirely and becomes H-group work on the case.
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The published starting band for the P30 Case-hardened steel sub-group is Soft state, carbide 180–280 m/min (590–920 sfm); Hardened case, CBN 100–180 m/min (330–590 sfm) at 0.05–0.15 mm/rev (.002–.006 ipr). It is a starting band for the whole sub-group, not a value tuned to 20MnCr5, so confirm on a sample part and adjust for condition, tool and rigidity.
Soft pre-carburized state: P-class CVD carbide. Hardened case (58–62 HRC): CBN or hard ceramic, like hard turning, with a honed/chamfered edge. 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.
EN 20MnCr5 (Werkstoffnummer 1.7147); US: AISI 5120 (nearest); JIS: SCr420 (nearest). At least one pairing is nearest-by-properties, not a drop-in equivalent: the material certificate decides.
The advisor compares what the makers publish for your material and operation and shows the source behind each answer, or tells you it could not verify.