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Speeds & Feeds

67 years of machining data, dialed in to your tool.

FM-304-16-120
FM-304-16-1203 Flute Aluminum Chatter-Free Long Reach High Performance Carbide End Mill
Ø 0.5″Flutes 3End Corner Radius
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Material

Operation

Cut
Strategy
Setup rigidity

Your machine

Machine-aware

Every recommendation is clamped to these limits — the numbers you see are numbers your spindle can actually run.

Material: 2024 (Aluminum & Magnesium)Cut: slotStrategy: normalSetup: rigidDOC limit: 0.5″Coating: Uncoated

Most aluminum jobs run uncoated — it's the most popular choice. Step up to DLC when built-up edge or tool life is the fight; diamond coating is for high-silicon aluminums.

Adjust feed — chip load80%recommended
ConservativePush once proven100% · tested max
Roughing

Spindle Speed

12,000

RPM · 100% of nominal

Feed Rate

230.4

IPM

Surface Speed

1,572 SFM

Chip Load / Tooth

0.0064 in

80% chip load

Width of Cut

0.500 in

Depth of Cut / pass

0.2000 in

Metal Removal Rate

23.04 in³/min

Spindle Power

5.76 HP

Finishing

Spindle Speed

12,000

RPM · 100% of nominal

Feed Rate

115.2

IPM

Surface Speed

1,572 SFM

Chip Load / Tooth

0.0032 in

80% chip load

Width of Cut

0.100 in

Depth of Cut / pass

0.2000 in

Metal Removal Rate

2.30 in³/min

Spindle Power

0.58 HP

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Starting recommendations from RobbJack's tested data — always verify on your machine, holder, and setup.

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The same data, proven in the field

$548,290saved per year drilling carbon-fiber aircraft$216,000saved per year trimming aircraft skins1,000%metal-removal increase in Inconel 718 (SPS)

CAD / CAM tool libraries

These same tested numbers, already in your CAM — download the RobbJack tool library with per-material cutting presets on nearly every tool.

Fusion 360 librarySiemens NXAll downloads

Starting speeds & feeds by material

Tested starting SFM, RPM, feed, and chip load by diameter — pick your material, then fine-tune in the calculator.

6061 Aluminum7075 AluminumCast Aluminum4140 Steel4340 Steel8620 SteelMild / Low-Carbon Steel304 Stainless Steel316 Stainless Steel17-4 PH StainlessTitanium 6Al-4VInconel 718A2 Tool SteelD2 Tool SteelDuctile Cast Iron

How the calculator works

This isn't a generic chip-load chart. It starts from RobbJack's 67 years of tested machining data for the actual tool, picks a safe and productive starting point, and keeps every recommendation inside your machine's limits. The numbers are deliberately conservative — many shops run faster once the process is dialed in.

See the logic in action

End mills — a full walkthrough4:10Set up the cut, read and adjust the numbers, open the tool's CAD & ISO data, and save your setup.
Slitting saws — a full walkthrough3:31Pick a blade by depth-to-width ratio and tooth count, adjust the feed, and match a thru-coolant arbor.

What each control does

Material & grade — the starting point
Pick the material and the engine loads RobbJack's tested surface-speed and chip-load band for it, plus the recommended coating. You don't need to know SFM or chip load — the numbers come from the data, not a generic textbook.
It picks the tool, not just the numbers
From the standalone calculator, enter the material and size and it selects the best-matching roughing and finishing end mill — or the right C- or K-Series saw blade — and calculates on that tool's real geometry. Open it from any tool page and it locks to that exact part instead.
Cut & strategy — slot vs. profile, conventional vs. trochoidal
Slotting is a full-width cut (the edge is engaged the whole time), so it's the most demanding; profiling takes less width and can run faster. Switch Strategy to Trochoidal for high-efficiency milling: a light radial width keeps the edge in the cut a fraction of the time, so the engine raises the allowable chip load and drives a full-depth pass. See the radial-width → time-in-cut relationship.
Setup rigidity — be honest about your fixture
Rigidity is the most overlooked factor in tool life. Set it to Light / weak for thin walls, long reach, or anything that can vibrate, and the engine backs off feed and chip load to keep the cut stable. A Rigid setup unlocks the faster numbers.
Total depth of cut — split into passes for you
Enter the full depth you need to remove. The engine divides it into passes that stay inside both the tool's geometry and your machine's power, and reports the depth of cut per pass. For hardened die/mold grades it splits the recommendation into separate wall and floor passes.
Machine limits & the power safety net
Enter your max spindle RPM, feed rate, and spindle power, plus a power safety headroom(40–95%). The engine models spindle power and keeps the depth of cut within your horsepower — if a cut would exceed your headroom it automatically reduces the depth and flags it, so you can't overload the spindle.

Reading your results

You get a roughing and a finishing card (wall and floor passes for hardened die/mold grades). The percentages next to RPM and chip load show how much room is left before the tool's tested limit.

Spindle Speed (RPM)
With “% of nominal” — how hard the recommendation pushes versus the tool's tested ceiling.
Feed Rate (IPM / mm·min)
Table feed for the recommended RPM and chip load.
Surface Speed (SFM / m·min)
Cutting speed at the edge — set by the material.
Chip Load / Tooth
With “% chip load” — feed per tooth versus the tested limit.
Width of Cut (WOC) / Slot Width
Radial engagement for the chosen cut and strategy.
Depth of Cut / pass (DOC)
Axial depth per pass after the power and geometry checks.
Metal Removal Rate
Material removed per minute — the productivity number.
Spindle Power (HP / kW)
Estimated load, kept inside your headroom.

Slitting saws

Switch to the Slitting Saw tab and enter outside diameter, arbor bore, and blade thickness. The engine picks the blade — stepping up to a K-Series for deep cuts — sets the tooth count and chip load by material, enforces a safe maximum depth of cut, and matches a thru-coolant NAB arbor to your bore. New to saw setup? Read the slitting-saw setup guide.

A starting point, not a limit

Always verify on your machine, holder, and setup. Want them dialed in for you?

Tap & cut testing →