Overview of indexable insert types
Which indexable insert is suitable for which purpose?
When working with indexable inserts, the question often arises as to which type of indexable insert is better suited for the desired result.
Which indexable insert is suitable for which material? What should you look out for when choosing? Our guide page will help you with these questions.
Indexable inserts are made from some of the hardest materials in the world, such as carbide, cermet, polycrystalline cubic boron nitride, polycrystalline diamant or cutting ceramics and, more rarely, HSS steel. They are manufactured using the sintering process and cause a change in the material. The sintering process can be imagined as a "baking together" of powdered or granulated starting materials. It often takes place under high pressure and heat.
What is the difference between an insert and an indexable insert?
Indexable inserts usually have several cutting edges. If one edge is worn, you can loosen the clamping screw, turn the insert over and use a new cutting edge. This also gives rise to the term "indexable insert".
Normal inserts, on the other hand, only have one edge for cutting and must be replaced with a new insert when worn.
Stability thanks to precisely fitting holder
Indexable inserts are placed in the precisely milled groove of the holder and can be fastened either with screws or clamps. Turning tools with indexable inserts are always form-fit. This means that the holders are optimally matched to the screwed-on or clamped indexable insert and therefore give it more stability.
Clearance angle for indexable inserts
- Indexable inserts for external turning have a cutting edge that itself has a clearance angle ≥ 0°. The clearance angle is the angle between the tool cutting plane and the flank face.
- Indexable inserts for internal turning, on the other hand, have a clearance angle of ≥ 7°. This means that the cutting edge is less stable, but small holes can be turned. Indexable inserts with a large clearance angle are used for internal boring.
In our range, you will find indexable inserts for milling with a clearance angle of 11° and indexable inserts for turning with a clearance angle of 7°. Smaller clearance angles are also suitable for machining harder materials.
Coatings for indexable inserts
In order to improve the properties of indexable inserts (such as increasing wear resistance, reducing sliding resistance during chip removal and improving heat resistance), they are coated. There are two main processes for this: PVD coatings and CVD coatings.
- PVD titanium-nitride (TiN) coated indexable inserts have a higher heat resistance and tool life and can be recognised by their golden colour. TiN-coated indexable inserts are suitable for both soft and hard materials.
- PVD titanium-aluminium-nitride-coated (TiAlN) indexable inserts are particularly suitable for machining hard materials such as stainless steel, steel and cast iron. The inserts can be recognised by their dark colour (black, anthracite).
- AlTiSiN-coated indexable inserts (aluminium, titanium, silicon, nitrite) are used for hard to very hard materials such as alloyed steel and cast iron and are copper-coloured. We offer AlTiSiN-coated indexable inserts for milling cutterheads / milling heads.
- Polished and ground indexable inserts have extremely sharp cutting edges and are used for machining aluminium, plastics, non-ferrous metals, brass, copper, bronze and stainless steel. These indexable inserts can be recognised by their silver colour.
As a general rule, the use of coolant increases the service life of an indexable insert.
Insert shape and geometry of indexable inserts
There are round, triangular, square, diamond-shaped and polygonal basic shapes of indexable inserts. The corner angle is also determined by the shape.
The geometry of the indexable insert is decisive for the surface quality, among other things. The cutting corner is important here - this can be pointed or have a rounded or chamfered corner. A chip breaker groove in the indexable insert also ensures that chips break quickly and do not wrap around the workpiece.
Indexable inserts with a narrow corner angle and a small cutting edge radius (contour turning tool) are particularly suitable for finishing the contour of the workpiece. Roughing tools, on the other hand, have a large corner angle and a large cutting edge radius. This allows a lot of material to be removed from the workpiece. Moulding turning tools are also ideal for fast and repeatable machining of complex geometries. The contour to be machined indicates the ideal size and shape of the indexable insert.
Standardised designation of indexable inserts
There are various standardised indexable inserts. These can be recognised by the respective standard designation. There are a total of 12 categories. In our online shop, however, we only list the first seven categories.
- 1st category: Insert shape (e.g. rhombus)
- 2nd category: Clearance angle (e.g. 7°)
- 3rd category: Tolerance class
- 4th category: Geometry
- 5th category: Cutting edge length (e.g. 11.6 mm)
- 6th category: insert thickness (3.97 mm)
- 7th category: Corner rounding (e.g. 0.4)
- 8. category: insert design
- 9th category: Cutting direction
- 10. category: bevel width
- 11th category: Bevel angle
- 12th category: Manufacturer's specifications
How to find the right indexable insert
The following questions are important in order to find the optimum indexable insert:
- Which material / which material should be machined? When asking this question, take into account the different coatings of the indexable inserts. Rule of thumb: The tool should always be made of a harder material than the material.
- What shape is the workpiece to be machined?
In order to be able to turn a right-angled shoulder, for example, a right or left-hand turning tool with a corner angle of less than 90° is used, depending on the side. For recesses, such as for a circlip, a parting tool is particularly suitable. Indexable inserts with a round insert shape, on the other hand, are used for ball turning or for finishing flat surfaces with a high surface quality. - What are the machining conditions?
Machining conditions are the sum of the conditions that are available to you personally. What material and size is the workpiece? Does the machine have sufficient capacity and drive power and does the cutting material have the right hardness and geometry? Do the measuring tools meet the requirements? - What surface quality should be achieved for the workpiece?
Do you want to achieve the best possible surface finish by finishing or remove a lot of material from the workpiece by roughing?
These questions will help you to select the right indexable insert in terms of use, cutting properties, tool life, cutting data and surface quality.
Subscribe now.
Get informed about new guides.
Would you like to be informed by us as soon as a new guide is published in our online shop? With our push notifications, you will be automatically informed about new articles in our guide section.
If you have already signed up for our push notifications, you will see a switch button here. To be notified as soon as a guide is published, you need to activate it.
If you do not see a switch button, please register for our push notifications first. You can do this on the following page:
On this page you can also customise the push notifications to your interests and select only the topics on which you would like to receive notifications from us.