WHAT ARE CARBIDE INSERTS?

Most likely, persons or companies who use metal cutting machines also work with carbide inserts. Carbide inserts make a huge difference in metalworking. This raises the question: how can such tiny pieces of metal have so much significance in metal precision-cutting? 

In this article, we will help you understand everything you must know about carbide inserts. We will cover the fundamentals, types, use applications, and how to choose the right carbide inserts for your project.

Carbide inserts are cutting elements used for materials such as cast iron, steel, aluminium, and high-temperature alloys. These materials are not all malleable. Suitable insert grades and cutting conditions can support productive, precise machining.

Cemented-carbide inserts commonly combine tungsten carbide particles with a metallic binder. Only the cutting edges and faces designated by the insert design are usable; not every insert can be flipped, and damaged edges must not be reused.

Due to some of these qualities, carbide inserts are perfect for heavy-duty, industrial machining. They bring a high degree of precision, efficiency, and consistency to your projects.

There are multiple types of carbide inserts, and in that vast world, there are various forms of carbide insert classifications. There are material-based classifications, shape-based (geometry) classifications, and function-based classifications.

For the context of this article, we will be focusing on the main types of carbide inserts under material-based classifications. They are as follows:

Titanium-carbide-based cutting materials are commonly described as cermets. Their hard phases and metallic binders vary by grade; nickel and molybdenum should not be presented as a universal binder recipe.

While titanium carbide-based inserts offer the basic toughness needed, these types of inserts are not as tough as tungsten-based carbides.

WC-Co combines hard tungsten carbide particles with a cobalt-rich metallic binder. Its hardness and toughness depend on composition and microstructure; the hard phase is tungsten carbide, not elemental tungsten.

The combination of these essential properties, in tandem with its versatility, makes tungsten-cobalt carbide insert the most commonly used type of carbide insert.

Grades containing tungsten carbide, cobalt binder, and titanium carbide (TiC) have properties determined by their full composition and microstructure. The presence of TiC alone does not establish a universal cutting-speed or wear-performance rating.

Select the grade using its application data and cutting conditions rather than assuming every such insert gives better performance at high temperatures.

Some cemented-carbide grades include tantalum carbide (TaC) as part of their composition. Performance depends on the complete grade; this addition alone does not establish peak hardness, thermal-shock resistance, or suitability for the highest cutting speeds.

Check the specific grade’s material and operating limits; no composition is suitable for every demanding industrial application.

Carbide inserts are indispensable for high-speed manufacturing today. But what makes them so valuable? Why should CNC machinists or tool makers not do without them?

Well, the answer to these questions can be found in the remarkable performance that carbide inserts bring to modern machining. These performances, however, are a result of certain sets of superior features that carbide inserts possess.

• High Hardness: 

Carbide hardness depends on grade and measurement method. HRA 89–93 is not a specification for every insert, and Rockwell numbers must not be treated as a linear ratio proving three to four times the hardness of HSS.

Carbide can retain useful hardness at elevated cutting temperatures, but it still softens and wears; the usable temperature range depends on the grade and cutting conditions.

• Improved Toughness: 

The high hardness property of tungsten carbide means it can get more brittle and less tough than HSS (which stands for high-speed steel, a material commonly used for cutting tools). It is for this reason that cobalt is included in the insert’s structure as a binder.

At a comparable WC grain size, increasing binder content generally raises toughness while affecting hardness and resistance to deformation. Grain size, binder composition, and the full grade design must also be considered.

• Wear Resistance:

Wear resistance must be compared under defined cutting conditions. The claimed 5–100 times advantage over HSS has no supporting test conditions here and should not be used as a general performance rating.

As a result, carbide inserts are ideal for use under high-speed cutting conditions. They help to maintain good cutting performance for a longer period of time, particularly in abrasive materials. 

• High Heat Resistance:

Carbide inserts can maintain their hardness even under increased thermal conditions, thanks to their high heat-resistant properties. The ability of a carbide insert to retain its high hardness is often called “Red Hardness” or “Hot Hardness.”

The stated 760°C and 1000°C values are not universal safe operating limits for carbide inserts. Use the grade supplier’s application data rather than treating these temperatures as guaranteed hardness-retention thresholds.

Understanding carbide inserts and material science is one thing. Knowing practical applications is another, and may be even more important. What are some practical applications of carbide inserts, and what problems do they solve?

To achieve optimal precision in the machining of high-strength materials like titanium, the aerospace industry relies heavily on carbide inserts. This is due to their high resistance to the extreme heat that is generated during the shearing process. 

For example, to craft a turbine blade made of Inconel, a nickel-based superalloy notorious for its extreme toughness and difficulty in cutting, an immense amount of heat will be generated. This level of heat can cause rapid tool wear. 

A carbide grade developed for the particular high-temperature alloy may be appropriate. Verify tool life and cutting data in the actual operation; it is not automatically longer-lasting than every alternative insert.

Just like in aerospace, carbide inserts are equally crucial in the automotive industry. Operations such as machining the deck face of a cast-iron engine block are typical in automotive plants. This operation requires incredible speeds in order to keep up with the high volume of production.

The problem arises when tool life is shorter than predicted, resulting in unexpected downtime and slower production rates due to frequent tool changes. This can cause so many problems for the production manager or supervisor. 

Appropriate carbide grades and planned edge changes can help manage production uptime. Tool life must be monitored, and neither predictable life nor freedom from unplanned downtime is guaranteed.

The importance of carbide inserts in the manufacturing of medical equipment and devices can not be overstated; it forms a core in the industrial aspect of the health sector. An example of such medical equipment is bone screws. 

Bone screws may use different specified implant materials; 316L stainless steel is one possible material family, not a universal requirement. Compliance depends on the applicable device design, material specification, manufacturing controls, and verification, not merely CNC turning.

A suitable sharp edge and controlled cutting conditions may reduce burrs. Inspect the finished features and perform any required deburring; carbide alone does not guarantee burr-free edges or tight tolerances.

Carbide inserts are generally vital to common tasks carried out in manufacturing and metalworking. Some of these tasks include milling, turning, and drilling.

The versatility of carbide inserts is particularly valuable to small and medium-sized metalworking shop owners. For example, when you need to carry out small shop tasks like making mild steel flanges at an economical standard, you will require a tooling solution that can handle both roughing and fine finishing.

Carbide inserts are the perfect solution for this. They are cost-effective, versatile, and improve productivity, thanks to their longer tool life.

Having a difficult time choosing the right carbide insert for your project? Do not fret, we have created an easy-to-understand outline of things to consider when choosing a carbide insert. 

Below is a table on how to select the right carbide insert tool:

If you have read this article up to this point, chances are you have already identified some benefits of using carbide inserts. For an even quicker comprehension, we will again highlight the primary reasons why you need carbide inserts. 

• Higher Material Removal Rates: Application-matched carbide inserts can support productive cutting. The achievable removal rate depends on the material, tool geometry, machine, and cutting data.

• Better Surface Finish: Suitable geometry and stable cutting conditions can support the required finish; a carbide insert does not automatically improve the surface.

• Longer Tool Life: Carbide may offer useful life in suitable applications. The claimed 10x advantage over HSS requires defined comparative tests and is not a general guarantee.

• Heat Resistance: Carbide grades have useful hot hardness, but each has operating limits. Select by verified application data rather than assuming suitability for every high-temperature operation.

Sourcing premium-quality carbide inserts can often be a daunting experience, especially considering the numerous subpar inserts currently flooding the market. 

To avoid purchasing low-quality carbide inserts that will eventually cost you more money and reduce productivity, always get your carbide inserts from Wuxi Sundi Precision Tools, an industry leader in the production of high-quality inserts and premium cutting tools. 

Choosing carbide inserts requires matching the grade and geometry to the machining task. Confirm application requirements with the tooling supplier before deciding whether a particular insert is suitable.

Contact us today to schedule a consultation with our team of experts and receive a complimentary quote on the highest-quality carbide inserts. Your first step to scaling up your production is now!