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BreakingChips

Steel · ISO P

8620 steel speeds and feeds

Also: SNCM220, 21NiCrMo2, 1.6523, 805M20, G86200

Starting points from the same engines as the calculators, with no tool or setup picked. The first number is where to start; the range is what the manufacturer charts allow. Open a calculator for your tool, machine and cut.

Draft data: researched from manufacturer charts, not yet reviewed by a machinist.

Machining notes

Annealed / as rolled175 HB

Turning

CutSFMFeed, IPRDepth, in
Finishing982669–1,383299 m/min0.0070.004–0.0100.18 mm/rev0.0220.004–0.0400.6 mm
Medium825562–1,162251 m/min0.0140.007–0.0200.34 mm/rev0.0850.012–0.1582.2 mm
Roughing775529–1,093236 m/min0.0170.010–0.0240.43 mm/rev0.1490.060–0.2373.8 mm

For a CVD carbide insert, general stability, 15 min tool life.

Milling, solid carbide end mill

Speed 343 (206–480) SFM · 105 m/min

Chip load per tooth, before chip thinning
Cutter ØIPTmm/tooth
1/8"0.00060.0005–0.00060.014
1/4"0.00160.0015–0.00170.041
1/2"0.00290.0028–0.00300.074
3/4"0.00420.0033–0.00500.105
1"0.00510.0041–0.00600.128

Drilling, Ø1/2" at 3×D

DrillSFMFeed, IPR
HSS7445–1150.01130.0070–0.0150
Cobalt9355–1150.01130.0070–0.0150
Solid carbide, through-coolant362265–6200.00970.0040–0.0153

Feeds scale with drill Ø (0.5" here): the drilling calculator sets them for yours.

Tapping

Cut tap
58 (40–80) SFM
Form tap
20 (10–35) SFM

Sources