Choosing the Right Cutting Tool Materials for Your Project
Every machining project is a battle against resistance, heat, and wear. To emerge victorious, you need an ally of unparalleled strength and resilience: the right cutting tool material.
It’s the shield against costly failures, the engine of streamlined production, and the key to unlocking maximum efficiency.
The right cutting tool material is the critical link between design and execution, determining the efficiency, precision, and longevity of your work.
Dive into this guide to discover the properties, types, and crucial considerations for selecting the perfect cutting tool material.
Properties of Cutting Tool Materials
The ability of a cutting tool to efficiently and accurately remove material is fundamentally determined by its inherent material properties.
In essence, the success of any machining operation, from roughing to precision finishing, rests upon the selection of a cutting tool material that can withstand the process’s rigorous demands.
An effective cutting tool material must possess a carefully balanced suite of characteristics, allowing it to maintain its integrity and cutting edge under extreme conditions [1].
Here are the key properties to look into that dictate a cutting tool’s effectiveness:
1. Mechanical Properties
- Hardness (Hot Hardness)
Hardness, particularly hot hardness, is of prime importance. It refers to the material’s ability to resist plastic deformation under high temperatures generated during cutting.
As cutting speeds increase, so does the heat generated at the tool-workpiece interface. A material that retains its hardness at elevated temperatures (i.e., exhibits good hot hardness) will maintain its cutting edge and resist wear, leading to optimal machining efficiency.
- Toughness
Think of toughness as a material’s ability to “take a hit” without breaking. It’s how well a material can absorb energy when it’s suddenly struck or impacted.
In practical terms, this is important when tools are used in situations where they might experience sudden, strong forces. For example:
- When a cutting tool is constantly starting and stopping, or when it hits harder spots in the material being worked on.
- When working with materials that are hard or that tend to break easily.
A “tough” material is less likely to chip, crack, or completely break under these conditions. This means the tool will last longer and perform more reliably.
Essentially, fracture toughness is a measurement of how much energy is needed to cause a crack to grow in a material. So a high fracture toughness means it takes a lot of energy to cause a crack to grow.
2. Thermal Properties
- Thermal Conductivity
High thermal conductivity is essential for channeling heat away from the cutting edge. This prevents excessive temperature build-up, which can lead to thermal softening (loss of hardness), accelerated wear, and even catastrophic failure.
Heat dissipation is also important for the workpiece. Excessive heat transferred into the workpiece can cause thermal distortion, and reduce the quality of the finished product.
- Thermal Shock
Thermal shock is the phenomenon where a material experiences rapid and significant temperature changes, leading to thermal stresses and potential cracking.
During interrupted cutting (e.g., milling) or when coolant is applied intermittently, the cutting tool undergoes rapid heating and cooling cycles.
A material with high thermal shock resistance can withstand these rapid temperature fluctuations without fracturing. This is particularly important for tools used in demanding applications where thermal cycling is frequent.
3. Chemical Inertness and Stability
Chemical inertness describes a material’s ability to resist undergoing chemical reactions when interacting with other substances. Put simply, it’s a material’s resistance to changing its composition.
During cutting processes, especially those generating high temperatures, chemical reactions can occur between the cutting tool and the workpiece.
These reactions can cause accelerated wear of the cutting tool, particularly a form of wear known as diffusion wear, which involves the trigger of chemical reactions (movement of atoms between the tool and the workpiece).
This characteristic is especially important when machining reactive materials like titanium or nickel-based alloys as they can readily react with many tool materials at elevated temperatures.
To improve chemical stability, coatings are frequently applied to cutting tools. These coatings act as barriers, preventing direct interaction and reaction between the tool and the workpiece [2].
In short, a chemically inert tool such as this will not readily react with the material it is cutting, even when subjected to high heat, thereby preventing rapid tool wear.
Types of Cutting Tool Materials & Their Applications
Choosing the right cutting tool is like picking the right tool for any job – it makes a huge difference in how well the task gets done.
1. High-Speed-Steel (HSS)
HSS is a strong type of steel that’s been specially treated to stay hard even when it gets hot to temperatures 600°C to 620°C [3]. It stands as a versatile and economical choice, particularly well-suited for low to medium-speed machining operations for its good toughness.
The performance of HSS is intrinsically linked to its alloy composition, which typically includes elements like tungsten, carbon, vanadium, and chromium, each contributing specific properties to enhance its overall durability and cutting efficiency.
Complex cutting tools, such as those used for hole-making, milling, threading, broaching, and gear cutting, frequently utilise HSS.
For those seeking reliable HSS solutions, Kota Cutting Tools offers a diverse range of products:
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KCT HSS-CO8 TICN 4 Flute End Mills – Regular
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DIN 345 – SOMTA HSS MTS Taper Shank Drills – Metric (M)
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2. Cemented Carbide
Cemented carbide is a composite material renowned for its high hardness and wear resistance, representing a significant advancement in cutting tool technology.
Formed by sintering hard carbide particles with a binder metal, typically cobalt, it exhibits exceptional performance across a wide range of machining operations with the capacity to withstand high temperatures allowing for increased cutting speeds and feeds.
Its versatility and adaptability make them widely employed for turning, milling, and drilling various materials, including steel, cast iron, and even some challenging alloys.
Carbide tools maintain their hardness up to approximately 850°C, a significant advantage over high-speed steel [4].
Although more brittle and expensive than HSS, its superior performance and extended tool life justify its use in demanding applications, especially in CNC machining environments where precisions are critical.
Check out these cemented carbide cutting tools by Kota Cutting Tools for your projects:
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KCT Tungsten Carbide Rotary Burrs – Tree with Radius End – SF
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KCT SOLID CARBIDE Straight Shank Jobber Drills
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3. Ceramics & Silicon Nitride
These materials enable high-speed machining by providing exceptional hardness and heat resistance. Their ability to withstand extreme cutting conditions, particularly when machining hardened steel, cast iron, and superalloys, is notable.
However, their inherent brittleness and susceptibility to thermal shock necessitate rigid machine setups and careful handling. While they offer significant advantages in specific applications, their fragility limits their versatility compared to other materials.
4. Cubic Boron Nitride (CBN) & Diamond Tools
CBN and diamond tools are the top-tier choices for cutting extremely hard materials and are perfect for machining tough steels and superalloys.
Diamond, the hardest material we know, is used for non-ferrous materials like aluminum and composites. These tools allow for very high-speed cutting and last a long time, making them ideal for challenging jobs.
However, they’re expensive and only work with specific materials. Notably, diamond tools can’t be used on steel or other iron-containing metals.
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Tips to Choose the Right Cutting Tool Material
Choosing the appropriate cutting tool material is essential for effective and accurate machining as the right selection involves more than just picking the hardest available option.
1. Consider the Workpiece Material
To begin, your workpiece material is the primary determinant as different materials have vastly different properties that affect cutting tool performance.
Characteristics of your workpiece material that dictate the necessary tool properties include its hardness, abrasiveness, thermal conductivity, and ductility.
Here are some examples:
| Workpiece Material | Recommended Cutting Tool Material | Description |
| Soft Steels (Low Carbon) |
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HSS is cost-effective for lower production runs. Carbide provides higher speeds and feeds. |
| Alloy Steels (Medium/High Carbon) |
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Coatings (TiN, AlTiN) enhance wear resistance. Ceramic cutting tools are used for very high hardness steels. |
| Stainless Steels |
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Requires tools with good edge toughness and heat resistance. |
| Aluminum Alloys |
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Sharp edges are essential to prevent built-up edges. Diamond coatings to reduce friction. |
| Cast Iron |
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Often abrasive; requires tools with good wear resistance. |
| Titanium Alloys |
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Difficulty in the machine due to high heat generation and reactivity. |
| Superalloys (Inconel, Hastelloy) |
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Extremely difficult to machine; requires high heat resistance and hardness. |
| Plastics |
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Sharp edges are crucial to prevent melting and a poor surface finish. |
| Composites (CFRP, GFRP) |
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Highly abrasive; requires tools with extreme hardness and wear resistance. |
2. Understand the Component’s Shape and Type
Another criteria to note when selecting the right tool material is knowing the component’s shape and type as it directly impacts tool geometry, material, and cutting parameters. This involves:
- Complex Geometries
Intricate shapes, such as those with narrow slots, sharp corners, or contoured surfaces, demand tools with specialized geometries. This includes custom-profile tools, small-diameter tools, or tools with specific corner radii.
- Deep Holes
Deep hole drilling presents challenges related to chip evacuation and tool rigidity. Tools designed for this application often feature specialised flute geometries and through-coolant capabilities to effectively remove chips and minimise heat buildup.
- Thin Walls
Thin-walled components are susceptible to vibration and deflection, which can lead to poor surface finish and dimensional inaccuracies. Choosing tools with optimised cutting geometries and low cutting forces will minimise this effect.
- Internal & External Features
Internal features, such as bores or internal threads, often limit tool access and require specialised tool designs, such as boring bars or internal threading tools. External features generally offer more flexibility in tool selection.
- Large vs Small Parts
Large parts may allow for higher cutting speeds and feeds due to increased stability and heat dissipation. However, maintaining dimensional accuracy over large surfaces is still a challenge.
Small parts require more precision and lower cutting forces to prevent damage or deflection. Tool selection, as well as work holding, are critical.
3. Considering the Machining Operations
The selection of cutting tool material is also heavily influenced by specific machining conditions and operations.
Cutting parameters, including cutting speed, feed rate, and depth of cut, directly impact heat generation, cutting forces, and chip load, necessitating careful optimisation based on workpiece and tool materials.
Machining operations themselves dictate tool requirements; roughing prioritises material removal with tough tools and high feed rates, while finishing demands sharp-edged tools with fine grain sizes and appropriate coatings for precise surface finish and dimensional accuracy.
Effective coolant and lubrication strategies, such as flood, mist, or MQL, along with proper concentration and pressure, are crucial for heat dissipation, chip evacuation, and friction reduction.
Finally, machine tool characteristics, including spindle speed, power, rigidity, and accuracy, establish the operational limits and achievable quality, ultimately guiding the selection of compatible cutting tools.
4. Establish the Required Level of Surface Quality
Achieving the required surface quality in machining necessitates a meticulous approach, beginning with a clear understanding of surface finish parameters such as Ra (average roughness), Rz (maximum roughness), and Rt (total roughness).
These parameters, alongside dimensional, geometric, and surface finish tolerances, define the acceptable range of surface imperfections.
Factors influencing surface quality are multifaceted, including tool geometry, where sharp cutting edges, appropriate nose radii, and chip breakers play critical roles.
Cutting parameters like speed, feed, and depth of cut must be optimised, while tool wear and vibration must be minimised to prevent surface degradation.
Precise measurement and inspection, utilising tools like surface roughness testers, coordinate measuring machines (CMMs), and optical comparators, are essential for verifying that the desired surface quality has been achieved.
Price vs Cost: Cutting Tool Material
When considering cutting tool materials, a simple price comparison can be misleading. A more comprehensive approach involves analysing the total cost of machining, where the initial tool price is just one factor.
Here’s a deeper look at the price vs. cost consideration, particularly in high-precision industries like aerospace:
1. Initial Price vs Total Cost
Lower-priced tools may seem attractive upfront, but they often lead to higher overall costs due to shorter tool life, lower cutting speeds, increased downtime for tool changes, and potentially, higher scrap rates.
Therefore, opting for premium tools, while more expensive initially, can offer significant cost savings for you in the long run.
2. Productivity & Efficiency
High-quality cutting tool materials, such as advanced carbides or ceramics, enable higher cutting speeds and feed rates, leading to increased material removal rates and reduced cycle times. This directly translates to higher productivity.
Improved tool life reduces the frequency of tool changes, minimising machine downtime and increasing overall efficiency.
3. Surface Finish & Accuracy
Premium tools often produce superior surface finishes and tighter tolerances, reducing or eliminating the need for secondary finishing operations. This saves time and labor costs.
4. Tool Life & Reliability
Durable cutting tool materials resist wear and breakage, leading to longer tool life and more predictable performance. This reduces the risk of unexpected tool failures, which can cause costly damage to workpieces and machines.
Reliability is important in unmanned machining, where tool failures can be extremely costly.
5. Long-Term Investment
Investing in premium cutting tools should be viewed as a long-term investment. While the initial cost may be higher, the resulting improvements in productivity, efficiency, and quality can lead to significant cost savings over time.
6. Materials Specifics
Some modern materials are extremely difficult to machine. Using lower quality tools will result in dramatically increased cost in both scrap and time. The initial investment in the correct tooling is mandatory.
In essence, the “price vs. cost” equation favors investing in high-quality cutting tool materials, especially in demanding applications where precision and efficiency are mandatory with no room for errors.
Invest in Performance with the Right Cutting Tool Material
Navigating the right cutting tool material for machining requires expert knowledge for perfect efficiency and precision. Don’t leave it to chance.
Our experts at Kota Cutting Tools can guide you through the complexities of material selection, ensuring you achieve optimal results for your specific application.
Contact us today for a consultation and discover the perfect cutting tool solution for your needs.
FAQ
1. What is the difference between ceramic and carbide inserts?
Understanding the differences between carbide and ceramic inserts is crucial as these two are popular insert types. Here are their differences:
| Feature | Carbide Inserts | Ceramic Inserts |
| Composition | Tungsten carbide (WC) + binder (e.g., cobalt) | Alumina (Al₂O₃), Silicon Nitride (Si₃N₄), etc. |
| Hardness | High | Very high |
| Toughness | Good | Brittle |
| Heat resistance | Good | Excellent |
| Cutting speed | Moderate to High | Very high |
| Applications | Versatile: steels, stainless steels, cast iron | Hardened steels, superalloys, high-speed machining |
| Wear resistance | Good | Excellent |
2. Is HSS or Carbide better for cutting tools?
HSS cutting tools are less expensive than carbide cutting tools. They maintain a significantly sharper edge, making them suitable for reducing materials that carbide cannot handle effectively. Additionally, HSS tools have a simpler sharpening process compared to carbide tools, and they allow for higher-speed cutting, which helps reduce production cycle times.
Carbide cutting tools, on the other hand, operate at cutting speeds 6–8 times faster than HSS tools. They produce high-quality surface finishes, are highly resistant to thermal deformation, and are ideal for demanding applications.
3. What is the strongest cutting material?
When discussing the “strongest” cutting material, it’s important to consider that “strength” can encompass various properties, including hardness, toughness, and wear resistance. However, in terms of sheer hardness, diamond stands out.
CBN comes in second for its effectiveness in machining hard steels and other ferrous alloys.
4. What is the first choice of material used for making cutting tools?
It’s essential to understand that the optimal material varies based on the specific application. However, cemented carbide holds a dominant position in modern machining for its:
- Versatility due to tungsten carbide particles and cobalt composition.
- Good balance of hardness, toughness, and wear resistance.
- Coated cemented carbide which will further enhance its performance.
Therefore, while other materials like high-speed steel, ceramics, and diamond have their specific applications, cemented carbide is often the go-to choice for general-purpose cutting tools.
5. How are tool life and material selection related?
Tool life and material selection are very closely intertwined as the material chosen for a cutting tool directly impacts how long that tool will last under specific machining conditions.
Harder materials, like diamond, last longer when cutting hard materials whereas tougher materials, like certain carbides, handle impacts better. Choosing the right material for the job, considering heat and chemical reactions, is crucial for maximising tool life. Essentially, the better the material matches the application, the longer the tool will last.
References
[1] Grigoriev SN, Fedorov SV, Hamdy K. Materials, properties, manufacturing methods and cutting performance of innovative ceramic cutting tools − a review. Manuf Rev, 2019; 6:19. doi:10.1051/mfreview/2019016.
[2] Podgornik B, Sedlaček M, Žužek B, Guštin A. Properties of Tool Steels and Their Importance When Used in a Coated System. Coatings. 2020; 10(3):265. https://doi.org/10.3390/coatings10030265
[3] Barchukov DAB, Lavrentiev AU, Romanenko EF, Filonovich AV. High-temperature tempering of high-speed steels with minimum content of retained austenite. Retrieved from: https://journal.uctm.edu/node/j2017-4/2_17-03_Barchukov_p621-625.pdf
[4] CNC Cookbook. Easy guide to cutting tool material selection. Accessed: 15th March 2025. https://www.cnccookbook.com/cutting-tool-materials/
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