Steel & Pre-Hardened Steel Milling

Choose an end mill for steel around the cut you need to make: a slot, shoulder, flat floor or curved surface. MSU offers GP, GPP and HPX carbide tools with square, ball-nose and corner-radius profiles.

These families cover material conditions below 55 HRC. For pre-hardened steel, use the measured hardness and steel grade together. For higher-hardness workpieces, compare Hardened Steel Milling.

Send a tool code and quantity, or describe the steel and feature you need to machine.

Find a Steel Milling Tool

Match the Steel and the Cut

The steel grade and heat-treatment condition narrow the tool choice. The feature then determines the end profile, cutting length and access you need.

Flat floors and shoulders Choose a flat cutting end and check the required corner detail.
Curved surfaces Match the ball radius to the contour and surrounding features.
Corner radii Match the tool-end radius to the floor-to-wall detail on the drawing.
Slots and open sides A full-width slot and a light side cut engage the tool differently; use cutting conditions for the intended operation.
Deep features Check the cutting length and holder clearance separately. Overall tool length alone does not establish usable reach.

For a roughing pass, allow for the stock that must remain for finishing. For the final pass, identify the surface and tolerance that the toolpath must produce.

Compare the available profiles and diameter ranges for your feature.

Compare Steel Milling Tools

Compare GP, GPP and HPX Tools

The Carbide End Mills range includes the following families. Compare end profile and dimensions before selecting a full model; the series name alone does not rank the tools for your job.

Series	Tool families	End profile	Diameter and hardness range	Feature
GP	GPE2, GPE4	Square End Mills	1-20 mm; below 55 HRC	Flat floors and shoulders
GP	GPB2, GPB4	Ball Nose End Mills	1-20 mm; below 55 HRC	Curved surfaces and contours
GP	GPR4	Corner Radius End Mills	1-20 mm; below 55 HRC	Floors with a specified corner radius
GPP	GPPE2, GPPE4	Square End Mills	1-20 mm; below 55 HRC	Flat floors and shoulders
GPP	GPPB2	Ball Nose End Mills	1-20 mm; below 55 HRC	Curved surfaces and contours
GPP	GPPR4	Corner Radius End Mills	1-20 mm; below 55 HRC	Floors with a specified corner radius
HPX	HPEX4	Square End Mills	3-20 mm; below 55 HRC	Flat floors and shoulders
HPX	HPBX2	Ball Nose End Mills	1-20 mm; below 55 HRC	Curved surfaces and contours
HPX	HPRX4	Corner Radius End Mills	3-20 mm; below 55 HRC	Floors with a specified corner radius

A matching diameter is only the first check. Cutting length, corner or ball radius, shank and overall length can differ between models.

Choose the cutting-data table for the series and operation you are using.

View Steel Cutting Conditions

Starting Conditions by Series and Operation

GP/GPP and HPX have different engagement conditions in these tables. Compare each with your intended cut before selecting a starting value.

GP / GPP Values HPX Values

GP and GPP Starting Values

The following GP/GPP values are starting points for profile milling (finishing), Ap = 0.2 D and Ae = 0.3 D. Cutter diameters are 2, 4, 6, 8, 10, 12, 14, 16 and 20 mm. Each fz column gives feed per tooth in mm/tooth for the stated cutter diameter.

Steel category	Subtype	Condition	HB	Vc (m/min)	fz Ø2	fz Ø4	fz Ø6	fz Ø8	fz Ø10	fz Ø12	fz Ø14	fz Ø16	fz Ø20
Non-alloy steel	C <= 0.25%	Normalized	125	140-240	0.018	0.047	0.076	0.104	0.135	0.149	0.162	0.176	0.189
Non-alloy steel	0.25% < C <= 0.55%	Normalized	190	230-330	0.020	0.052	0.084	0.116	0.150	0.165	0.180	0.195	0.210
Non-alloy steel	0.25% < C <= 0.55%	Quenched and tempered	210	230-330	0.020	0.052	0.084	0.116	0.150	0.165	0.180	0.195	0.210
Non-alloy steel	C > 0.55%	Normalized	190	190-310	0.019	0.049	0.080	0.110	0.143	0.157	0.171	0.185	0.200
Non-alloy steel	C > 0.55%	Quenched and tempered	300	140-240	0.018	0.047	0.076	0.104	0.135	0.149	0.162	0.176	0.189
Non-alloy steel	Free-cutting steel	Quenched and tempered	220	190-310	0.019	0.049	0.080	0.110	0.143	0.157	0.171	0.185	0.200
Low-alloy steel	Not specified	Annealed	175	190-310	0.019	0.049	0.080	0.110	0.143	0.157	0.171	0.185	0.200
Low-alloy steel	Not specified	Normalized	300	140-240	0.018	0.047	0.076	0.104	0.135	0.149	0.162	0.176	0.189
Low-alloy steel	Not specified	Quenched and tempered	380	110-210	0.017	0.045	0.072	0.100	0.129	0.142	0.155	0.168	0.181
Low-alloy steel	Not specified	Quenched and tempered	430	90-190	0.016	0.043	0.069	0.095	0.123	0.135	0.148	0.160	0.172
High-alloy steel / high-alloy tool steel	Not specified	Annealed	200	140-240	0.018	0.047	0.076	0.104	0.135	0.149	0.162	0.176	0.189
High-alloy steel / high-alloy tool steel	Not specified	Quenched and tempered	300	140-240	0.018	0.047	0.076	0.104	0.135	0.149	0.162	0.176	0.189
High-alloy steel / high-alloy tool steel	Not specified	Quenched and tempered	400	110-210	0.017	0.045	0.072	0.100	0.129	0.142	0.155	0.168	0.181

HPX Starting Values

The following HPX values are starting points for shoulder milling (finishing), Ap = 1.5 D and Ae = 0.03 D. Cutter diameters are 4, 6, 8, 10, 12, 14, 16, 18 and 20 mm. Each fz column gives feed per tooth in mm/tooth for the stated cutter diameter.

Steel category	Subtype	Condition	HB	Vc (m/min)	fz Ø4	fz Ø6	fz Ø8	fz Ø10	fz Ø12	fz Ø14	fz Ø16	fz Ø18	fz Ø20
Non-alloy steel	C <= 0.25%	Normalized	125	160-280	0.063	0.090	0.117	0.144	0.171	0.198	0.234	0.261	0.288
Non-alloy steel	0.25% < C <= 0.55%	Normalized	190	220-340	0.070	0.100	0.130	0.160	0.190	0.220	0.260	0.290	0.320
Non-alloy steel	0.25% < C <= 0.55%	Quenched and tempered	210	220-340	0.070	0.100	0.130	0.160	0.190	0.220	0.260	0.290	0.320
Non-alloy steel	C > 0.55%	Normalized	190	200-320	0.067	0.095	0.124	0.152	0.181	0.209	0.247	0.276	0.304
Non-alloy steel	C > 0.55%	Quenched and tempered	300	150-270	0.063	0.090	0.117	0.144	0.171	0.198	0.234	0.261	0.288
Non-alloy steel	Free-cutting steel	Quenched and tempered	220	200-320	0.067	0.095	0.124	0.152	0.181	0.209	0.247	0.276	0.304
Low-alloy steel	Not specified	Annealed	175	200-320	0.067	0.095	0.124	0.152	0.181	0.209	0.247	0.276	0.304
Low-alloy steel	Not specified	Normalized	300	150-270	0.063	0.090	0.117	0.144	0.171	0.198	0.234	0.261	0.288
Low-alloy steel	Not specified	Quenched and tempered	380	120-240	0.060	0.086	0.112	0.138	0.163	0.189	0.224	0.249	0.275
Low-alloy steel	Not specified	Quenched and tempered	430	100-210	0.057	0.082	0.107	0.131	0.156	0.180	0.213	0.238	0.262
High-alloy steel / high-alloy tool steel	Not specified	Annealed	200	150-270	0.063	0.090	0.117	0.144	0.171	0.198	0.234	0.261	0.288
High-alloy steel / high-alloy tool steel	Not specified	Quenched and tempered	300	150-270	0.063	0.090	0.117	0.144	0.171	0.198	0.234	0.261	0.288
High-alloy steel / high-alloy tool steel	Not specified	Quenched and tempered	400	120-240	0.060	0.086	0.112	0.138	0.163	0.189	0.224	0.249	0.275

D is cutter diameter; Ap is axial depth and Ae is radial width of cut. Vc is cutting speed in m/min; fz is feed per tooth in mm/tooth. Keep each feed value paired with its stated diameter. These are series-level starting points: the selected end profile and setup still require a trial. See the End Mill Selection Guide, End Mill Coating Guide and End Mill Flute Count Guide for geometry, coating and flute-count considerations.

Changing from profile finishing to a shoulder or slot? Send the intended engagement with your tool reference.

Discuss Steel Cutting Conditions

Check Tool Support and the Finished Surface

Before a trial, check how the assembled tool reaches the feature and how the machined result will be measured.

Support and clearance

Use the shortest projection that reaches the feature. Check the holder and tool body through the complete machining path, including entry and exit.

Tool and part measurements

Identify the cutting dimensions that need inspection separately from the part tolerance and surface finish. Tool-measurement equipment is described in Factory and Quality Control; use Downloads for dimensional drawings.

Use the model drawing to check the full dimensions before ordering.

Find Tool Drawings

Order a Standard Tool or Discuss a Drawing

Choose a standard model when its profile and working dimensions fit the part. For an unavailable size or clearance, a drawing defines what needs to change.

Standard sizes

Use the selected end profile and full dimensions to identify the tool. Include the model code and quantity when requesting a repeat order.

A tool to your drawing

If the required diameter, reach or profile is unavailable, email a dimensioned drawing for Custom Cutting Tools. Mark the critical geometry and tolerances, with the steel grade and hardness.

MOQ is normally 5–10 pieces, confirmed by quotation. Samples and sample freight are charged. Production timing is confirmed for the order; shipping time is stated separately. See Ordering and Delivery for purchasing terms.

Email the drawing with the material and critical dimensions to discuss the tool you need.

Discuss a Custom Tool

Steel Milling Questions

Can I select an end mill from steel hardness alone?

No. Hardness narrows the options, but the steel grade, heat-treatment condition, end profile and machining operation must also match the tool.

Are the GP/GPP and HPX tables directly comparable?

They describe different cuts. GP/GPP values are for profile finishing at Ap = 0.2 D and Ae = 0.3 D; HPX values are for shoulder finishing at Ap = 1.5 D and Ae = 0.03 D. Compare tools under the same actual operation.

Does a ball nose leave the same floor as a square end mill?

No. A square end mill has a flat cutting end. A ball nose has a rounded profile for curved surfaces; choose it to suit the part contour and toolpath.

What if I need more reach than the standard tool provides?

Compare the cutting length, body clearance and projection after clamping. If the available dimensions cannot reach the feature, email a section drawing with the required depth and clearance.

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