Carbide Insert Identification Guide
Read carbide insert codes in two stages: identify geometry and size, then interpret the manufacturer’s grade and chipbreaker markings. Check the dimensions and tool connection before selecting a replacement.
The worked turning-insert example below shows how a designation relates to physical dimensions. Other insert systems use their own code keys, so begin with the correct tool type.
Have an unclear marking? Include every visible character and the holder or cutter-body code.
Ask an Identification QuestionRead the Insert Geometry Code
Teaching example: CNMG 120408 is a metric turning-insert designation. Read it as C–N–M–G–12–04–08 using the applicable turning-insert code key.
C identifies an 80° rhombic shape, N a 0° clearance angle and M a tolerance class. G describes the insert type, including the hole and chipbreaker arrangement. These fields identify geometry; they do not select the carbide grade. The Carbide Inserts range includes several tool types with different identification details.
For this example, 12 is the size code, 04 the thickness code and 08 the nominal 0.8 mm nose radius. The published dimension row gives a 12.7 mm inscribed circle and 4.76 mm thickness: the number 12 should not be read as a measured 12 mm diameter. The links below identify the operation to check after reading the marking.
Use the operation and physical shape to narrow down the insert type.
Compare Insert TypesSeparate Grade and Chipbreaker Markings
A full manufacturer reference adds fields beyond the base geometry. For example, Sandvik lists CNMG 12 04 08-MM 2015: -MM is its geometry designation and 2015 its grade.
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Shape
Identify shape first, then check access to the feature. In turning, a larger nose angle supports a stronger edge but can require more power and increase vibration; a smaller angle improves access.
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Clearance or relief
Record the clearance designation and check the matching holder or cutter pocket. Clearance is one part of assembly fit, together with insert size, seat and clamping details.
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Tolerance
M in CNMG is a tolerance class. It does not mean a workpiece material group or a carbide grade here. The position of a symbol within the designation matters.
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Size and thickness
CNMG 120408 and the ANSI designation CNMG 432 are paired by manufacturers for this nominal size. In the inch designation, 4 represents 4/8 in inscribed circle, 3 represents 3/16 in thickness and 2 represents 2/64 in nose radius. Metric and inch tables may show rounded values.
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Nose radius or corner detail
Match the radius to the drawing and cutting conditions. In turning, a larger nose radius strengthens the edge but increases radial force; a smaller radius can help with light cuts and vibration.
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Manufacturer geometry, grade and hand
Chipbreaker names and grade numbers use the manufacturer’s key. In the Sandvik example, -MM and 2015 must be interpreted with Sandvik’s data. The same suffix or grade number from another brand need not mean the same geometry, substrate or coating. Check hand where specified.
This teaching example shows how a turning-insert designation is read. Grooving, threading, milling and drilling inserts may use different or proprietary designation formats. Use the code key for the exact system.
Compare the identification details for the operation you need.
Compare Insert DetailsFind the Matching Insert Type
Once you know the operation, check the fields below. A turning-insert designation does not provide a complete key for every grooving, threading, milling or drilling system.
Turning Inserts
Open product page →Identification focus
Check shape, clearance, tolerance, size, thickness and nose radius. Then select the grade for the material and the chipbreaker for finishing, medium cutting or roughing.
Confirm before ordering
Complete model, dimensions, hand and holder or system requirement.
Small Parts Machining Inserts
Open product page →Identification focus
Check the complete compact-insert model and dimensions. Add the holder code and feature drawing, since restricted access and small dimensions affect the assembly choice.
Confirm before ordering
Complete model, dimensions, application and holder or system requirement.
Grooving and Parting Inserts
Open product page →Identification focus
Check the grooving or parting system, cutting width and radius where specified. Match hand, blade or holder and the required groove depth to the exact model.
Confirm before ordering
Complete model, dimensions, hand and holder or system requirement.
Threading Inserts
Open product page →Identification focus
Check internal or external thread, hand, profile and pitch. A full-profile insert is matched to a pitch and profile; a V-profile insert can cover a pitch range but does not form the thread crest.
Confirm before ordering
Complete model, dimensions, thread form and holder or system requirement.
Milling Inserts
Open product page →Identification focus
Check the milling insert’s shape, size, thickness and corner geometry, then match grade and chipbreaker to the cut. Confirm the exact cutter-body pocket and clamping system.
Confirm before ordering
Complete model, dimensions and cutter-body or system requirement.
Shallow Hole Drilling Inserts
Open product page →Identification focus
Check the drilling insert model, dimensions and designated position in the drill body where specified. Match the complete drill-system code before selecting a replacement.
Confirm before ordering
Complete model, dimensions and drill-system requirement.
Find dimension tables in Downloads. Compare the complete model, grade and chipbreaker rather than treating a base geometry code as a finished tool specification.
Choose the insert type, then check the complete model and assembly fit.
Compare Insert TypesCheck Dimensions and Tool Fit
A geometry code narrows the search. The holder pocket, support surfaces and clamping arrangement determine whether the selected insert can be assembled correctly.
Identify the operation and model
Use the marked designation and operation to compare Carbide Inserts. Keep the brand, full model and any grade or chipbreaker markings with the reference.
Compare the dimension drawing
Check shape, size, thickness, nose radius, clearance and hole details against the drawing. A matching top view can conceal a different thickness, relief angle or clamping feature.
Downloads →Check the holder or cutter body
Compare the exact insert with the seat, shim and clamping specifications for the holder or cutter body. Use Toolholders to identify the assembly. A matching base code alone does not establish fit or equivalent cutting behavior.
Compare the complete model’s dimensions before selecting a replacement.
Check Insert DimensionsIdentify an Insert with Missing Markings
Start with photographs and measurements. Dimensions can narrow the candidates; they may leave several grades or chipbreaker geometries that look alike.
Measure the features that distinguish candidates
Photograph both faces and the side with a scale. Record shape and angle, inscribed circle or the dimension used in the drawing, thickness, hole diameter and hole profile. Add corner radius where measurable; for grooving or threading, record cutting width or thread profile and pitch. Note damaged features that may affect measurement.
Recover the information a photograph cannot show
Check the original packaging, order history and holder marking for the full reference. Color alone does not establish grade or coating chemistry. A worn edge may also hide the original chipbreaker and corner geometry.
Find current catalogs in Downloads and inspection information for inserts in Quality Control. Include any dimensional or inspection-document requirement in your inquiry.
Use the drawing to compare your measurements with possible models.
View Insert DrawingsAsk a Technical Question
Send the complete marking or catalog reference when the model, dimensions, grade, chipbreaker, hand or assembly fit needs confirmation.
Known marking
Provide every visible character, including grade and chipbreaker suffixes, plus the brand if known. Add the operation and the holder or cutter-body code.
Missing marking
Record shape, size or inscribed circle, thickness, hole details and corner radius where measurable. Include cutting width for grooving and profile and pitch for threading.
Email clear photographs
Use the contact form for your question. Email views of both faces, the side, markings and holder pocket using the address on the contact page. Include a scale and the measured dimensions.
Send the complete marking and catalog context to MSU for model confirmation.
Contact MSUCarbide Insert Identification Guide Questions
What is carbide insert nomenclature?
It is a code system for identifying insert geometry and size. Manufacturer fields add grade, chipbreaker and other details. Use the key for the particular insert system.
What does CNMG 120408 tell me?
In the turning-insert example, C is an 80° rhombic shape, N is 0° clearance, M is a tolerance class and G identifies the insert type. The numeric fields identify size, thickness and nominal nose radius.
Are CNMG 120408 and CNMG 432 different sizes?
Manufacturers pair these metric and ANSI designations for the same nominal size: 12.7 mm inscribed circle, 4.76 mm thickness and nominal 0.8 mm radius in the metric table. Verify the complete product drawing, grade and geometry.
Can I interpret grade and chipbreaker codes across brands?
Use each manufacturer’s key. Matching suffixes or grade numbers do not establish matching substrates, coatings or chipbreaker geometry.
Does a matching base code guarantee holder fit?
Check the full model, dimensions, clearance, hole and clamping details against the exact holder or cutter-body specification. The base geometry code alone does not confirm the assembly.
Where can I compare complete model dimensions?
Use the dimension drawings in Downloads and the relevant Carbide Inserts type. Keep grade and chipbreaker fields separate from the geometry and size comparison.
What should I send when the marking is missing?
Email photographs of both faces and the side, measured size, thickness, hole details and corner radius where measurable. Include the holder or cutter-body marking, operation and any packaging or order reference.