Cutting Tool Inserts Information

Cutting Tool InsertsCutting tool inserts are replaceable attachments for cutting tools that typically contain the actual cutting edge. Cutting tool inserts applications include:

  • boring
  • construction
  • cutoff and parting
  • drilling
  • grooving
  • hobbing
  • milling
  • mining
  • sawing
  • shearing and cutting
  • tapping
  • threading
  • turning
  • brake rotor turning


Cutting tool inserts can have many different geometries. Round or circular inserts are used in applications such as button mills or in radius groove turning. Some types are adjustable to employ unused edge portions once part of the edge is worn.

Three-sided inserts include triangle and trigon shapes. Triangle inserts have a triangular shape; three equal sides and three tips with included angles of 60 degrees. A trigon insert is a three-cornered insert resembling a triangle, but with a modified triangular shape, such as bowed sides or intermediate angles on the sides, to allow for higher included angles at the tips.

Cutting Tool Inserts

Four-sided insert shapes include diamond, square, rectangular and Rhombic. A diamond insert is a four-sided insert with two acute angles used for material removal. Square cutting tips have four equal sides. Rectangular inserts have four sides, two of which are longer than the other two. These inserts are often used for grooving, where the short sides contain the actual cutting edge. Rhombic or parallelogram inserts are four-sided, with an angle on the sides for cutting point clearance.

Additional insert shapes include pentagon, which has five equal sides and angles and octagonal inserts with eight sides.  

In addition to inserts that are defined by their geometry, a number of types are differentiated by their tip angles. A ball nose mill is an insert with a hemispheric "ball nose" whose radius is one half of the cutter diameter, useful for machining female semicircles, grooves or radii. A radius tip mill is a straight insert with ground radius on tips, typically for use on milling cutters. In a chamfer tip mill, the insert side or ends contain an angled section on tip to produce an angled cut or a chamfered edge on the workpiece, typically attached to milling cutter holders. A dogbone is a two-edged insert with a narrow mounting center and, as the name implies, a broader cutting feature on both ends, often used for grooving. Tip included angles can be 35, 50, 55, 60, 75, 80, 85, 90, 108, 120, and 135 degrees.



The inscribed circle (I.C.), or the diameter of the circle that fits entirely within the insert geometry, generally categorizes insert size. This is used for most indexable inserts, except for rectangular and some parallelogram inserts, where length and width are used. Important specifications for cutting tool inserts include thickness, radius if applicable, and chamfer angle if applicable. Common features for cutting tool inserts include unground, indexable, chipbreaker, and dished. Insert attachments can be screw-on or no hole.



Cutting tool inserts are commonly constructed of carbide, micrograin carbide, CBN, ceramic, cermet, cobalt, diamond PCD, high-speed steel, and silicon nitride. Coatings help to increase wear resistance and insert life. Coatings for cutting tool inserts include titanium nitride, titanium carbonitride, titanium aluminum nitride, aluminum titanium nitride, aluminum oxide, chromium nitride, zirconium nitride, and diamond DLC.


Metal cutting solutions from Sandvik Coromant


Related Information

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Sandvik Coromant



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