How to Choose the Right Carbide Inserts?

The industry of cutting tools has expanded ten-fold in the last few years. Among hundreds of options, it is hard to choose the right tool. Selecting a tool that can produce low cutting forces with a good surface finish and the smooth cutting action is complex.

This article is for you if you want to know how to choose the correct carbide inserts. Here you’ll get to know everything about the proper carbide inserts for your cutting applications.

Let’s get started!

What are Carbide Inserts?

Carbide inserts are tools used to accurately machine metals, including steels, carbon, cast iron, high-temperature alloys, and other non-ferrous metals. These are replaceable and come in various styles, grades, and sizes.

There are some primary considerations on how to choose the correct carbide inserts. One of those is the cutting operation, whether turning, Milling, or drilling. Carbide is more expensive per unit than other typical tool materials, and it is more brittle, making it susceptible to chipping and breaking. To offset these problems, the carbide cutting tip itself is often in the form of a small insert for a more enormous tipped tool whose shank is made of another material, usually carbon tool steel. This benefits from using carbide at the cutting interface without the high cost and brittleness of making the complete tool out of carbide. Most modern face mills use carbide inserts and many lathe tools and endmills.

Carbide inserts are used at high speeds that enable faster machining, ultimately resulting in better finishing. Choosing a correct carbide insert is vital because it can risk damaging the insets, machine, and cutting product.

What makes Carbide Inserts great?

Here are some of the reasons that make carbide inserts so great as compared to other cutting tools:

  • Carbide inserts are efficient and cost-effective as compared to other similar cutting tools.
  • Some carbide inserts like tungsten are highly durable and result in longer work life.
  • Carbide inserts come in different shapes and grades that can be used in various applications.
  • Carbide inserts produce a much better surface finish quality than other tools.

Material of Inserts

Inserts are made of several different materials but commonly constructed of carbide, micro-grain carbide, ceramic, CBN, cermet, diamond PCD, cobalt, silicon nitride, and high-speed steel. The coating over the insert increases the wear resistance and life span of this cutting tool. These coatings include titanium nitride, titanium carbonitride, titanium aluminum nitride, aluminum titanium nitride, aluminum oxide, chromium nitride, zirconium nitride, and diamond DLC.

Manufacturing of Carbide Inserts

Let’s discover the manufacturing process of carbide inserts to know better about its types and uses;

The suitable carbide insert for specific machining operations helps to stay ahead in competition among the cutting tools industry.

Carbide inserts, mainly tungsten and cobalt, start in powder form. Then in the mill, the dry raw material is mixed with a combination of ethanol and water. This mixture results in a gray slurry solution with a consistency like a yogurt drink. This mixture is dried and then sent to a laboratory for a quality check. This powder comprises agglomerates, small balls of 20 to 200 microns diameter, and then transported to pressing machines where inserts are made.

Carbide Inserts Geometry

Carbide inserts geometry can be divided into three basic styles optimized for several operations, including roughing, finishing, and medium. Here are some diagrams that will explain each geometrical shape’s working area, based on geometrical chip breaking with the depth of cut.

1.     Roughing

Roughing includes a high depth of cut and feed rate combinations. This process requires the most increased edge security.

2.     Finishing

Finishing includes watery depths of cuts and low feed rates. This process requires low cutting forces.

3.     Medium

This operation includes a wide range of deep cuts and feed rate combinations.

Carbide Inserts nose radius

The nose radius, RE, is a crucial factor in carbide inserts operations. Carbide Inserts are available in different sizes of nose radius. The selection depends on the depth of cut and feed and influences the surface finish, chip breaking, and insert strength.

Entering angle for carbide Inserts

The entering angle, KAPR (or lead angle, PISR), is the angle between the cutting edge and the feed direction. It is essential to choose the correct entering/lead angle for a successful turning operation. The entering/lead angle influences:

  • Chip formation
  • The direction of cutting forces
  • Cutting edge length in cut

Role of Geometry in Manufacturing Inserts

Mainly people consider macro geometry and carbides’ physical shape when the role of geometry is discussed. Here, microgeometry is equally essential that deals with the microscopic form’s cutting edge.

The geometry of an insert is an essential aspect because it deals with the shape of chip control. Different shapes and angles provide optimal results in breaking chips, depending upon their material and application.

Using advanced technology, the cutting surface of an insert is given a round, oval, or any other geometrical shape. Significant benefits in insert life and stability have been seen with emerging technology. It is safe to say that future technological advances will drive further development in the field, and even more substantial achievements will occur.

Types of Carbide Inserts

According to their shape and material used, several different types of carbide inserts are used for various purposes. These inserts are replaceable attachments for cutting tools that typically consist of the actual cutting edge. These carbide inserts include:

  • Construction
  • Hobbing
  • Milling
  • Mining
  • Tapping
  • Sawing
  • Drilling
  • Grooving
  • Cut off and parting
  • Shearing
  • Cutting
  • Threading
  • Turning
  • Brake rotor turning

Carbide inserts have different geometrical shapes. For instance:

Round or Circular Inserts

Round or circular carbide inserts are used in applications of button mills and radius groove turning.

Triangle or Trigon Inserts

Triangle or Trigon carbide inserts have a triangular shape with three equal sides and three tips with angles of 60 degrees. They are three-cornered inserts that resemble a triangle but with a modified form like bowed sides or medium-sized angles that include grades at the tips.

Four-Sided Carbide Inserts

Four-sided carbide inserts include diamond, rhombic, square, and rectangle shapes. Diamond-shaped carbide inserts are four-sided with two acute angles used for material removal.

Square-shaped carbide inserts have four equal sides. On the other hand, Rectangular carbide inserts have four sides. Two of the sides are longer than the other two. These types of carbide inserts are used for grooving purposes where the short sides of inserts have the actual cutting edge.

Rhombic or parallelogram-shaped carbide inserts are also four-sided, with an angle on the sides for cutting point clearance.

Other shaped carbide inserts include pentagon with five equal sides and angles, and octagonal inserts have eight sides.

Other than the shapes, carbide inserts are also differentiated by their tip angles. Here are some carbide inserts with different tip angles:

  • Ball Nose Mill:

A ball nose mill carbide insert has a ‘hemispheric’ ball nose whose radius is half than the cutter diameter. This carbide insert helps machine female semicircles, grooves, or radii.

  • Radius Tip Mill:

A radius tip mill carbide insert is a straight insert with a ground radius on tips. This type of carbide insert is used on milling cutters.

  • Chamfer Tip Mill:

A chamfer tip mill contains an angle section on the tip to produce an angled cut or chamfered edge on the workpiece.

  • Dog bone Carbide Insert:

A dog bone carbide insert is a two-edged insert with a narrow mounting center and also offers a broader cutting feature at both ends. This type of carbide insert is used for grooving. It’s tips included angles that can be 35, 50, 55, 60, 75, 80, 85, 90, 108, 120, and 135 degrees.

Uses of Carbide Inserts

People have been using carbide inserts since the late 1920s. These cutting tools are ubiquitous in the metal cutting world. Here are some of the carbide insert’s applications in the metal cutting industry. Carbides are extremely helpful for dozens of business owners, construction workers, and many other industries worldwide.

Making of Surgical Tools

In the medical profession, doctors and surgeons rely on accurate and durable tools for all kinds of medical procedures and insert carbides are one of them.

The medical industry is the most common industry for the use of carbides. However, the base of the tool itself is crafted with titanium or stainless steel, and the tip of the tool is made of tungsten carbide.

In Jewelry Making

Carbide inserts are widely used in the jewelry-making industry. They are used for both jewelry shaping and in the jewelry itself. Tungsten material falls behind the diamond on the hardness scale, and it is an excellent material used in making wedding rings and other jewelry pieces.

Moreover, jewelers rely on efficient tools to work on the expensive pieces, and carbide and tungsten inserts are one of them.

In Nuclear Science Industry

Tungsten carbide inserts are also used in the nuclear science industry as effective neutron reflectors. This material was also used during early investigations in nuclear chain reactions, especially for weapons protection.

In Hard Turning and Milling

Turning is an almost flawless process for ceramics. In general, it is a continuous machining mechanism that allows a single carbide insert to be engaged in the cut for a longer time. This is an excellent tool to generate the high temperatures that make ceramic inserts perform optimally.

On the other hand, Milling can be compared to interrupted machining in turning. Each carbide insert on the tool body is in and out of the cut during each cutter revolution. If compared to turning, hard Milling needs much higher spindle speeds to achieve the same surface speed

 for working efficiently. 

To meet the surface speed of a turning mechanism on a three-inch diameter workpiece, a three-inch diameter milling cutter with four teeth must run four times the turning speed. With ceramics, the object generates a threshold of Heat per insert. Therefore, each insert must travel faster to generate a single point turning tool’s heat equivalent in milling operations.

Carbide Inserts for Difficult Materials  

The tools cutting industry has drastically changed, and these changes can be seen in inserts for Milling and turning the inappropriate materials. This section highlights that how carbide inserts change the inappropriate materials.

In today’s world, carbide coated with carbide, cermet, cubic boron nitride (CBN), and polycrystalline diamond (PCD) inserts play a vital role.

Carbide inserts with unique geometries and coatings withstand mechanical shock and Heat while resisting abrasive wear. However, using these inserts productively can require various external factors—one of which may be a partnership with a knowledgeable tool supplier.

Carbide inserts are used in making different materials like steel alloys. These steel alloys are becoming harder in many applications. This steel hardens to 63 RC are commonly used in the dye and mold industry.

Mold makers used to cut the parts before heat treating but now precision machining tools are used in the fully hardened condition to avoid any heat treating distortion. With this technique, even fully hardened materials can be machined economically with the carbide inserts.

For instance, aerospace machining uses carbide inserts. They used round carbide inserts when they want to machine hard steels. This is how profile provides a more robust tool without vulnerable sharp corners.

Choosing Carbide Insert Grades

Keeping an eye on grades is also essential when choosing carbide inserts. Always consider toughened grades because they provide edge security against the high radial cutting forces. They also offer severe entry and exist shocks when encountered in harden sheets.

Some specially formulated high-temperature grades withstand the heat generation when steel hardens to 60 RC. On the other hand, shock-resistant carbide inserts with an aluminum oxide coating counter the high temperatures generated by milling hard steels.

Carbide inserts, mainly tungsten and cobalt, start in powder form. Then in the mill, the dry raw material is mixed with a combination of ethanol and water. This mixture results in a gray slurry solution with a consistency like a yogurt drink. This mixture is dried and then sent to a laboratory for a quality check. This powder comprises agglomerates, small balls of 20 to 200 microns diameter, and then transported to pressing machines where inserts are made with different grades.

Carbide Inserts for Milling

Like other industries, carbide inserts are also used in the milling industry. They solve every conceivable application problem. These carbide inserts include ball nose carbide inserts, high feed carbide inserts, toroid carbide inserts, backdraft carbide inserts, and flat bottom carbide inserts. All these carbide inserts solve specific problems in

the milling industry.

Most of the machining performance on molds and dies focuses on common mold materials in the milling industry. Only top form geometrics are different from one another. Here are some mold materials that are preferable in the milling industry:

Aluminum

Aluminum is the preferred mold material in the milling industry for some segments. These metal removal rates are as high as eight to ten times faster than machining steel.

In recent times, aluminum manufacturers have developed better high-strength materials with hardness characteristics ranging from 157 to 167 Brinell. It is hard to machine very smooth surfaces on aluminum, so polishing becomes a critical operation in the final process.

Milling aluminum requires C2 carbide grade inserts for rough and C3 grade for finishing. Only general grade carbide inserts grades with a medium grain with excellent wear resistance for roughing and finishing applications where sharp edges are required.

Beryllium Copper

Beryllium Copper is also the preferred mold material in the milling industry for some segments. These metal removal rates are also as high as eight to ten times faster than machining steel. Their hardness level ranges from 10 RC to 40 RC, which is nearly double that of aluminum.

Carbide Inserts for Sintered Metals

Due to advancements in technology, powder metallurgy produces extra hard sintered metals for various industries. For such industries, a powdered nickel composite alloy is made by combining tungsten and titanium carbide to achieve hardness from 53 to 60 RC.

To machine sintered metals, inserts’ choice depends upon the material and workpiece. Carbide inserts having positive rake geometrics can effectively cut thin-wall sintered metals stock. However, thick-walled sintered metal parts need ceramic inserts with negative cutting edge geometry that provide smooth flat surface area to the workpiece.

The carbide particles and the nickel alloy matrix reach up to 90 RC. When milling such materials, the carbide inserts coated with different materials suffer rapid flank wear with flat primary cutting edges. However, the extra hard particles within the insert create ‘microchatter’ that speeds up the insert wear. It would help if you were careful because sometimes carbide inserts also fracture under the sheer pressure of machining the hard shock.

Carbide inserts have a high capacity to cut hard power metals containing tungsten and titanium metals.

Carbide Inserts for Supper Alloys

Heat resistant super alloys (HRSAs) are extensively used in the aerospace industry and gain acceptance in the medical, automobile, power generation, and semiconductor industries. Heat resistant super alloys like Waspalloy and titanium 6Al4V are joined with titanium, magnesium, and aluminum matrix that altogether possess machining challenges.

These alloys are super hard, and they need higher cutting zone temperatures greater than 2,000°F. If we talk about carbide inserts used to cut these alloys, these are even super hard.

To machine Heat resistant super alloys (HRSAs), inserts’ choice depends upon the material and workpiece. Carbide inserts having positive rake geometrics can cut thin wall Heat resistant super alloys (HRSAs) stock effectively. However, thick-walled alloy parts need ceramic inserts with negative cutting edge geometry that provide smooth surface area to the workpiece.

Carbide Inserts for Turning

Turning is an almost flawless operation for ceramics. Commonly, it is a continuous machining process that allows a single insert to be engaged in the cut for relatively long periods. This is an excellent tool to generate the high temperatures that make ceramic inserts perform optimally.

On the other hand, Milling can be compared to an interrupted mechanism in turning. Each carbide insert on the tool body is in and out of the cut when each cutter revolves. Compared to turning, hard Milling needs much higher spindle speeds to achieve the same surface speed for efficient working.

To engage the surface speed of a turning mechanism on a three-inch diameter workpiece, a three-inch diameter milling cutter with three teeth must run with a minimum of four times the turning rate. With ceramics, the object generates a potential of Heat for each carbide insert. Therefore, in milling operations, each carbide insert must travel faster to generate a single point turning tool’s heat equivalent.

Carbide Inserts for Threading

Carbide inserts are also used in the threading industry. High-quality lay-down triangular carbide inserts provide a solution for most threading industry needs. These carbide inserts manage a wide range of applications, from essential to complex ones.

In the threading industry, carbide inserts feature the following things:

  • A large variety of carbide insert grades and coatings tailored for different materials and manufacturing processes
  • High-quality threads produced by the inserts
  • Capable of cutting lines as small as 0.5 mm
  • Inserts available for internal and external jobs and both right-hand and left-hand threads

To match a threading operation’s surface speed on a three-inch diameter workpiece, a three-inch diameter threading cutter with four teeth must run four times the turning speed. With ceramics, the object generates a threshold of Heat per insert. Therefore, in threading operations, each insert must travel faster to generate a single point turning tool’s heat equivalent.

Conclusion

Choosing the right carbide insert is not an easy task, but if you keep all the mentioned parameters in mind, this process can be easy and convenient. Don’t hang with the insert’s brand image because it will not affect its performance. Always choose a carbide insert according to your use, whether for Milling, threading, or any other industry.

This post will help you choose suitable carbide inserts by considering all those critical factors to judge.

Here is a quick list of everything to look at when selecting carbide inserts:

•       Shape of carbide inserts

•       Types of carbide inserts

•       Usage in industries

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