In modern machining technology, tool wear is one of the decisive factors for productivity, quality and cost-effectiveness. Indexable inserts are high-performance tools that are subjected to enormous forces and temperatures. Over time, every cutting edge wears out - but how quickly this happens depends on numerous influencing factors.
A certain amount of wear is unavoidable and even desirable as long as it remains controllable. Predictable wear enables a predictable tool life and stable production. Problems arise if the cutting edge is worn prematurely or unevenly - this can lead to dimensional deviations, poor surface quality, increased cutting forces or even tool breakage.
In order to understand and minimise tool wear correctly, a distinction must be made between two levels:
Wear mechanisms – the physical and chemical processes that lead to wear of the tool. These include abrasion, adhesion, diffusion, oxidation, thermal stress and mechanical overload.
Forms of wear – the visible and measurable changes to the indexable insert resulting from the mechanisms. These include flank wear, crater wear, notch wear or cutting edge chipping.
At the same time, several mechanisms can act in parallel - for example, high abrasive wear can lead to flank wear, while diffusion wear increases crater wear.
Effective wear management does not mean preventing wear completely - that is impossible. Rather, it is about slowing it down, controlling it and utilising it economically. The following factors play a key role here:
In the following, we examine the most important wear mechanisms and forms in detail, explain their causes and show practical measures for optimising tool life. Because if you understand tool wear, you can control it - and that means fewer tool changes, higher quality and more economical production.
Reduce tool wear, optimise tool life and lower your production costs - with the right strategy. We analyse your process and optimise your production.
The wear of indexable inserts is the result of various physical, mechanical and chemical processes. These wear mechanisms determine how quickly and in what form the cutting edge is worn. Several mechanisms can occur simultaneously or reinforce each other.
Abrasive wear occurs when hard particles from the workpiece material (e.g. carbides, nitrides or cast scale) act like abrasive grains on the tool surface. These particles grind both on the rake face and the flank face of the tool and remove material.
Typical signs:
Amplifying factors:
Reduction measures:
Adhesive wear usually occurs with soft, elastic materials. The adhesive effect of these materials is increased by an unfavourable process temperature and pressure conditions. This can result in removed workpiece material particles adhering to the indexable insert and then tearing off again. Cutting material can also be torn off, which weakens the cutting edge.
Typical signs:
Amplifying factors:
Reduction measures:
Diffusion wear is a chemical process in which atoms are exchanged between the tool and the workpiece. As a result, the cutting material loses its stability, which leads to a weakening of the cutting edge.
Typical signs:
Amplifying factors:
Reduction measures:
At high temperatures, cutting material components react with the oxygen in the environment and form oxide layers. These are often less stable than the original material and can peel off, weakening the cutting edge.
Typical signs:
Amplifying factors:
Reduction measures:
Thermal wear is caused by extreme temperatures or temperature differences during the cutting process. If a hot tool is cooled abruptly (e.g. due to an irregular supply of cooling lubricant), stresses are created that lead to fine cracks. An excessively high process temperature can also weaken the cutting material, which favours plastic deformation of the tool cutting edge.
Typical signs:
Amplifying factors:
Reduction measures:
Mechanical wear occurs when the cutting edge is overstressed by excessive cutting forces or impact loads. This can lead to microcracks, crumbling or even complete insert breakage.
Typical signs:
Amplifying factors:
Reduction measures:
While the wear mechanisms describe the underlying processes that lead to wear, the forms of wear show how these manifest themselves on the cutting edge. The type of visible wear provides important information on which mechanisms are at play and which measures should be taken to optimise the service life of the indexable inserts.
Characteristics:
A continuous wear zone along the clearance face of the insert
Typically occurs during long-term, uniform wear processes
Often the main tool life criterion, as it develops gradually
Cause:
Abrasive wear due to hard particles in the workpiece
High cutting speeds intensify the effect
Consequences:
Dimensional inaccuracies and reduced surface quality
Increased cutting forces and heat generation
Solution:
✔ Use harder or coated inserts
✔ Lower cutting speed, increase feed rate if appropriate
✔ Select the correct cutting edge geometry
Flank wear is especially problematic in internal machining, where slender tools with long overhangs are used. This increases the risk of vibrations caused by flank wear.
The IN©turn system from MAS features a cutting edge geometry optimized for both sharpness and edge stability. Combined with a high-performance coating, this reduces cutting forces and thus friction on the clearance face.
Characteristics:
Cause:
Consequences:
Solution:
✔ Reduce cutting speed
✔ Use harder or coated inserts (e.g. Al₂O₃, CVD coatings)
✔ Apply more positive cutting edge geometry for smoother chip flow
✔ Optimize cutting parameters and tool geometry
Characteristics:
Cause:
Consequences:
Solution:
✔ Adjust cutting speed to suit the material
✔ Use more positive cutting edge geometries
✔ Choose polished cutting surfaces or coatings with improved sliding properties
Characteristics:
Cause:
Consequences:
Solution:
✔ Improve cooling to reduce oxidation
✔ Use more positive rake angles or alternative coatings
✔ Vary depth of cut to avoid localized overloading
Characteristics:
Cause:
Consequences:
Solution:
✔ Use continuous or no cooling (avoid intermittent coolant supply)
✔ Choose cutting materials with high thermal shock resistance (e.g. cermet, ceramic, CBN)
✔ Adjust cutting speed to keep temperature peaks low
Characteristics:
Cause:
Consequences:
Solution:
✔ Reduce cutting speed
✔ Use harder cutting materials or thicker coatings
✔ Adjust feed rate
Characteristics:
Cause:
Consequences:
Solution:
✔ Check workpiece clamping and machine rigidity
✔ Use a more stable cutting edge geometry
✔ Choose tougher cutting materials or coated inserts
Characteristics:
Cause:
Consequences:
Solution:
✔ Use a tougher cutting material substrate
✔ Reduce feed rate and depth of cut
✔ Inspect tools regularly and replace them in time
Chip hammering is a mechanical wear mechanism that occurs when chips are not removed cleanly after shearing and hit the cutting insert or intermediate layer. This repeated impact can lead to chipping, flaking or micro-fractures on the cutting edge.
Turning or milling produces chips that are shaped differently depending on the workpiece material, cutting conditions and tool geometry. If chips do not flow away in a controlled manner, they can wind up, hit the tool or get caught, causing enormous forces to act on the indexable insert.
Chip hammering is particularly problematic:
Repeated chip blows can cause microcracks or material chipping on the cutting edge. In the long term, this leads to
✔ Select the correct chip breaker geometry:
✔ Control chip flow through optimised cutting edge geometry:
✔ Adjust cutting values:
✔ Adjust the setting angle to direct the chip flow in a different direction
✔ Use high-pressure cooling (HPC) to actively blow chips away
✔ Use air or MQL to keep chips away from the tool
Every type of wear has its cause - and a solution. Optimise your machining specifically for maximum tool life.
Wear is an unavoidable part of machining - but it can be specifically controlled and minimised. The right combination of cutting material selection, cutting value optimisation and process adaptation can maximise the service life of indexable inserts and significantly improve economic efficiency.
The service life of a cutting tool depends largely on the cutting material. The right choice can significantly reduce abrasion, diffusion and thermal wear.
Tip:
| Cutting Material | Advantages | Application Area |
|---|---|---|
| Carbide (HM) | High toughness, good wear resistance | Standard machining, steel, stainless steel, cast iron, aluminum, non-ferrous metals |
| Cermet | High hot hardness, low adhesion | Finishing operations, hard steels |
| CBN (Cubic Boron Nitride) | Extremely hard, resists diffusion wear | Hard turning, hardened steels, heat-resistant alloys, cast iron, sintered metals |
| PCD (Polycrystalline Diamond) | Maximum wear resistance, no diffusion wear | Aluminum, non-ferrous metals, fiber-reinforced plastics |
| Ceramic | Heat-resistant, resists notch wear | Heat-resistant alloys, cast iron |
Coatings protect the cutting material from abrasive, adhesive, and thermal wear.
Tip:
| Coating | Properties | Application Area |
|---|---|---|
| TiN (Titanium Nitride) | Reduces adhesion, increases toughness | Stainless steels, aluminum, copper |
| TiCN (Titanium Carbonitride) | Harder than TiN, high abrasion resistance | Steels, non-ferrous metals |
| Al₂O₃ (Aluminum Oxide) | Resistant to high temperatures | Heat-resistant steels, cast iron |
| TiAlN (Titanium Aluminum Nitride) | High thermal resistance | Dry machining, carbide machining |
Incorrect cutting parameters are one of the most common causes of excessive tool wear.
Tip:
| Type of Wear | Cause | Solution |
|---|---|---|
| Flank wear | Cutting speed too high | Reduce speed, slightly increase feed |
| Crater wear | High temperatures / diffusion | Reduce speed and feed, use Al₂O₃ coating |
| Built-up edge | Cutting speed too low | Increase speed, use polished cutting edges |
| Notch wear | Cutting speed too high or too low | Adjust speed, vary depth of cut, select a more positive geometry |
| Thermal cracks | Alternating temperatures | Apply consistent cooling or switch to dry milling |
Coolants and lubricants (cutting fluids) play a major role in controlling temperature and removing chips.
When is cooling recommended?
When is dry machining better?
Tip:
The cutting edge geometry influences cutting forces, chip formation, and heat generation.
Tip:
| Geometry | Advantages | When to Use |
|---|---|---|
| Positive rake | Reduces cutting forces | For soft or adhesive materials |
| Negative rake | High stability, long tool life | For hard materials, cast iron, titanium |
| Wiper inserts | Improved surface finish | For finishing or high-feed machining |
| Large corner radius | Lower point load | For high feed rates and stable cutting conditions |
Vibrations and unstable clamping increase mechanical wear and may cause cutting edge chipping or tool breakage.
Tips to Prevent Tool Breakage:
✔ Use rigid workpiece clamping → prevents uncontrolled vibrations
✔ Check machine accuracy → minimize spindle play
✔ Choose the right tool holder → reduces micro-vibrations
Technological advancements are fundamentally reshaping the machining industry.
Where tool wear was once monitored through fixed tool life intervals or manual inspections, today's innovations — including digital technologies, new cutting materials, and sustainable production strategies — enable intelligent and cost-effective control of the entire tool lifecycle.
Modern indexable inserts and tool holders are increasingly equipped with sensors that capture real-time data on temperature, pressure, and vibration. This information is fed directly into CNC controls or cloud-based analytics platforms, where AI algorithms assess tool condition and predict wear. As a result, tool changes can be precisely scheduled, and unplanned downtime is significantly reduced.
Artificial intelligence is fundamentally transforming machining. Machine learning analyzes large datasets, identifies wear patterns, and automatically adjusts cutting parameters. This enables dynamic process control, where feed rate, cutting speed, and depth of cut are optimized in real time to minimize tool wear.
Predictive maintenance makes tool management more accurate:
Instead of relying on fixed tool life intervals, each tool is used to its full potential. Modern CNC machines operate increasingly autonomously — AI-driven control systems plan tool changes more efficiently and optimize machining strategies without human intervention. The result: greater machine availability and reduced tooling costs.
New high-performance coatings such as AlTiN and AlCrN offer even greater heat resistance and are ideal for high-speed machining. Nanocoatings combine multiple protective mechanisms and, in some cases, can even partially self-heal. For non-ferrous metals and aluminum, diamond-like carbon (DLC) coatings create extremely smooth chip surfaces and effectively prevent built-up edge formation.
Cutting materials are also evolving:
While CBN and PCD remain the go-to solutions for maximum tool life in abrasive materials, increasing research is focused on sustainable alternatives to cobalt-bonded carbides.
Machining must become more sustainable — and manufacturers are increasingly implementing recycling programs for carbide and CBN tools. Reconditioning reduces raw material consumption and lowers CO₂ emissions. At the same time, the production of indexable inserts is becoming more energy-efficient through the use of resource-saving coating technologies and cobalt-free binders.
Another step toward sustainability is the growing use of dry machining and minimum quantity lubrication (MQL), both of which drastically reduce the consumption of cutting fluids.
The future of indexable insert technology lies in the combination of intelligent, self-optimizing processes and sustainable materials.
Digital monitoring, next-generation coatings, and AI-driven process control will further reduce tool wear and enable more cost-efficient manufacturing.
Fully automated CNC systems, longer-lasting cutting materials, and resource-efficient production methods are no longer distant visions — they are already being implemented in industrial settings.
Those who embrace these innovations early not only gain a competitive economic edge, but also ensure long-term success in an increasingly digital and sustainable manufacturing landscape.
