End Mill Selection Guide
Choose an end mill from the feature you need to machine and the material you need to cut. Match the cutting end to the drawing, then check diameter, cutting length, reach and clearance.
A tool that reaches the bottom of a pocket still needs room for its neck, shank and holder. Once the geometry fits, compare flute count, coating and cutting conditions for the job.
Have a drawing or an end mill that is not working as expected? Tell us the feature and material.
Discuss an End MillMatch the Cutting End to the Part
A flat floor, curved surface, edge radius and undercut each need a different cutting shape. Start with the feature that controls the choice.
Square ends machine flat floors; ball noses follow curved surfaces; corner-radius ends leave a defined floor-to-wall radius. Small dimensions, undercuts or edge finishing may require one of the other tool forms below.
Find the cutting shape your part requires, then compare the available sizes.
Explore End Mill TypesChoose the Tool Step by Step
Work through the part drawing before choosing a model. Each step rules out tools that cannot make the feature or fit the setup.
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Material and condition
Identify the alloy and its condition, including hardness when relevant. A tool suited to annealed steel may need a different geometry or coating for the same steel after hardening.
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Roughing or finishing
Roughing removes stock; finishing must meet the final size and surface requirement. Decide whether one tool can do both or whether to leave allowance for a separate finishing pass.
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Feature and diameter
The cutter must fit the narrowest region and the required internal corner radius. Also allow room for the planned toolpath; matching cutter diameter to slot width creates a full-width cut.
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Cutting length and reach
Cutting length covers the edge engaged in the cut. Reach and neck clearance determine access below the shank. Use only the length the feature needs and check clearance around the holder.
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Flutes and coating
Choose chip space and cutting edges for the engagement, then a surface treatment for the material and cutting conditions. The End Mill Flute Count Guide and End Mill Coating Guide explain those choices.
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Setup and starting data
Check shank fit, projection, runout, workholding and chip removal. Use starting speed and feed for the selected tool and operation; a full slot and a light side cut place different demands on it.
Teaching example: a flat-bottom pocket has an internal wall radius and a small floor-to-wall radius on its drawing. First compare square and corner-radius ends against those features. Then choose a diameter that can follow the wall corner, sufficient cutting length and the shortest practical reach. Flutes, coating and starting data follow the alloy and engagement. This example illustrates a selection sequence, not a tool model or cutting-parameter recommendation.
Compare the tool profiles against the floor, walls and edges on the drawing.
Compare Cutting ShapesCompare End Mill Shapes and Uses
Use the shape comparison to narrow the tool type. The dimensions in the last column determine whether it fits your part.
| Tool type | Feature or task | Dimensions and conditions to check |
|---|---|---|
| Square End Mills | Flat floors, shoulders and slots with a square floor-to-wall corner | Diameter, cutting length and reach; check any specified corner preparation |
| Ball Nose End Mills | Curved surfaces and 3D contours | Ball diameter, reach and toolpath spacing for the surface requirement |
| Corner Radius End Mills | Flat floors with an allowed floor-to-wall radius | Corner radius, diameter, cutting length and clearance |
| Micro End Mills | Small features and restricted access | Exact diameter and reach; close control of runout and deflection |
| Roughing End Mills | Bulk stock removal before final sizing | Roughing geometry, chip space and allowance left for finishing |
| T-Slot End Mills | Undercuts and T-slots | Head diameter and thickness, neck clearance and entry access |
| Corner Rounding End Mills | A specified radius on an outside edge | Form radius and clearance around adjacent faces |
| Chamfer Mills | Angled edges and deburring | Included angle, tip size and usable cutting diameter |
| Tapered Ball Nose End Mills | Curved features needing a tapered tool form | Ball radius, taper and interference along the toolpath |
| Single-Flute End Mills | Cuts where chip space is a leading concern | Material suitability, end geometry and cutting data for the model |
Compare the available Carbide End Mills once the shape is clear. A square floor-to-wall corner and an internal wall corner are different features: cutter diameter still limits the latter.
Check the dimensions of the tool type that fits your feature.
Find End Mill SizesMatch Material and Cutting Conditions
The same end shape can be offered in different geometries and coatings. Choose a series for the workpiece grade, hardness and operation.
End shape and size
Match the Carbide End Mills model to the end profile, diameter, cutting length and reach you selected. Include shank size and corner or ball radius when comparing two similar codes.
Workpiece-specific conditions
Hardness, alloy condition and engagement affect the starting conditions. For the materials below, compare the stated operation and tool series with your job before applying cutting data.
Chip space and surface treatment
Flute count changes chip space and feed calculation. Coating choice depends on the substrate, edge and workpiece as well as heat and adhesion. Use these comparisons when those choices remain open.
Use the full model code to check diameter, cutting length and reach.
Find Model DimensionsCheck the Dimensions Before a Trial
Check both the cutting dimensions and the space around the tool. Overall length alone does not tell you whether the tool can reach a deep feature.
Length and clearance
Check cutting length, neck diameter, reach, shank diameter and overall length on the tool drawing. The fluted portion must cover the intended cut, while the neck and holder must clear nearby walls.
Trial result
Begin with the selected tool’s recommended conditions for the operation. Check chip evacuation, sound, wear and the finished part. Measure the dimensions and surface requirement that determine whether the trial is acceptable.
Find model drawings in Downloads. For measurements or reports needed with an order, see Quality Control and specify the features to be checked.
Compare the tool drawing with the clearance and tolerances your part requires.
View Dimension TablesGet Help with a Tool Choice
Describe the feature you need to produce or the problem with your current tool. Start with the details you have; add the drawing and cutting conditions where available.
For a new part
Share the material and condition, feature dimensions, depth and required finish. State whether the task is roughing, finishing or both.
For an existing problem
Include the current tool code, speed, feed, axial and radial engagement, projection and coolant method. Describe the wear, breakage or part defect you are trying to resolve.
Drawings and photos
Describe the requirement in the contact form and email the drawing or photos using the address on Contact MSU. Mark the critical dimensions and show any clearance around the holder.
Send your question and a tool reference, or describe the part you need to machine.
Contact MSUEnd Mill Selection Questions
What should I choose first: diameter or end shape?
Start with the required feature and cutting shape, then choose a diameter that fits the narrowest area and internal wall radius. Check toolpath clearance before settling on the size.
Can a corner-radius end mill replace a square end mill?
Only where the drawing allows the radius it leaves at the floor-to-wall junction. Match that radius as well as diameter and reach; similar overall dimensions do not make the profiles interchangeable.
What is the difference between cutting length and reach?
Cutting length is the axial length of the cutting edges. Reach describes access below the shank on a reached tool. A long-reach, short-flute tool can access a deep feature without cutting along the full depth at once.
Can I keep the same speed and feed for a full slot and side milling?
Use data for each operation. Full-width engagement puts more of the cutter in contact and makes chip clearance more demanding than a light side cut. Review feed, depth and evacuation for the selected tool.
Why is the part corner radius important?
An end mill cannot generate an internal wall radius smaller than its cutting radius by ordinary contour milling. A separate floor-to-wall radius is controlled by the tool’s end-corner geometry.
Can one tool rough and finish the part?
It may, if the geometry and remaining edge condition meet the final size and finish. Separate roughing and finishing tools allow each operation to use a suitable geometry and finishing allowance.
What helps when two tools look suitable?
Compare the complete drawings for diameter, corner form, cutting length, reach and shank size. Then compare the stated material and operation, flute geometry, coating and required setup.