CBN (cubic boron nitride) is a very hard cutting tool material that can machine the materials that cannot be cut effectively using a traditional tool, such as hardened steels, some cast irons, and some super alloys. In these cases both the wear of the cutting tool and the surface finish of the machined part can start to become quite problematic.

The hardness and wear resistance of CBN make it an ideal choice for high-speed hard turning operations.

However, selecting a tool grade of CBN does not instantly result in a favorable outcome. The grade, insert shape, size, workpiece material, and cutting conditions all need to match the job. This is where we need to find suitable CBN Inserts.

In this guide, we’ll look at what makes CBN suitable for hard machining, how to choose the right insert for different applications, and where HyperCBN can fit into the process.

Why Hardened Materials Change the Machining Game

Machining a hard material has additional complications over soft materials. As a material becomes harder, more resistance is experienced at the cutting edge. The degree of tool wear is increased, and the significant heat produced in the cutting process is noted. A tool that works well on a regular workpiece may not give the same result on hardened steel or other high-hardness materials.

There is also the question of surface finish. When the cutting edge starts wearing quickly, the finish can change from part to part. Frequent tool changes can slow down production too.

This is why tool selection matters so much in hard machining. The application is concerned when the need for hardness and wearing is required, with cubic boron nitride inserts. We use this type of insert for hardened steel, cast iron, and superalloys depending on the grade and the condition of machining. The goal is not simply to use the hardest tool available. It is to use a tool that matches the job.

What Actually Makes CBN Inserts Different?

CBN is not just another cutting material. Its value comes from how it handles the kind of conditions that make hard machining difficult.

Think about three things:

1. High Hardness

CBN is an exceptionally hard cutting tool material. This means it is an ideal candidate for machining very hard workpieces, such as the harder steels, cast iron, and a number of the superalloys.

2. Resistance to Wear

Hard machining conditions may cause significant wear to a cutting edge. CBN is generally very wear resistant, allowing it to continue effectively for some time in hard machining.

3. High-speed Machining

The right CBN Turning Inserts can be used for high-speed finishing when the insert grade and cutting conditions are suitable. HyperCBN offers different grades for applications ranging from continuous hardened-steel cutting to interrupted cast-iron cuts and superalloy finishing.

So, when someone says CBN is useful because it is “hard,” there is more to it than that. Its hardness and wear resistance make it useful for specific machining jobs where ordinary tooling may struggle.

Don’t Choose the Grade Before Looking at the Material

In making any choice regarding CBN inserts, the workpiece must come first and the catalogue second. Materials cut at various speeds and feeds display different wearing characteristics, so the optimum CBN grade for one job might well not suit another.

Before selecting a grade, look at these points:

Material being machined:

Hardened steel, cast iron, and superalloys have different machining requirements. The insert grade should suit the material you are working with.
Workpiece Hardness

One must identify the hardness of the workpiece and then determine the necessary grade. HyperCBN inserts have individual grades for particular hardness ranges and intended uses.

Abrasiveness

Various materials will more quickly erode the cutting edge. The abrasiveness of the workpiece must therefore be investigated.

Thermal Conductivity

The magnitude of heat passed between tool and workpiece affects the result of the cutting operation. As a factor impacting tool longevity, the workpiece’s thermal characteristics should be identified.

Type of Cut

One may either face, profile, or turn. This would translate, in terms of workpiece requirements, to either an uninterrupted or continuous cutting operation. This parameter should be used when selecting an appropriate Cubic Boron Nitride Inserts Grade.

Just put simply. “Learn the material before selecting the grade.” It also stops us from ‘thinking every hard-machining situation is the same situation.”

Continuous and Interrupted Cuts Need Different Thinking

The type of cut is another important factor when selecting CBN turning inserts. Continuous and intermittent cutting, which may have different demands placed upon the cutting edge, but consider:

• Continuous cutting – the edge remains in contact with the workpiece throughout the cut.
• Interrupted cutting — The cutting edge repeatedly enters and leaves the workpiece.
• Hardened steel — HyperCBN offers the HCBN5010 grade for continuous cutting of hardened steels from 50 to 65 HRC.
• Cast iron — HCBN5020 is designed for interrupted cuts in cast iron.
• Cutting conditions — Speed, feed, and depth of cut should match the selected grade.
• Edge demands — Interrupted cuts can place different loads on the cutting edge than continuous cuts.
• Grade selection — Choose the grade according to both the workpiece material and cutting condition.

Getting this part right can make the difference between simply having a hard tool and having CBN Cutting Tools that actually suit the machining operation.

Why Insert Shape and Size Matter More Than You Think

Choosing the right CBN inserts is not only about the grade. The shape and size of the insert also need to suit the machine setup and the job.

Shape:
Each of the various shapes of the insert yields different cutting-edge rake and strength. The common shapes are square, triangle, diamond, and others depending on the function.

Dimensions:
The size of the tool should be appropriate to the existing tooling arrangement and the size of the workpiece. Larger is not always better.

Machine Setup:
The machine, tool holder, cutting direction, and available working space all play a role in the selection.

The Practical Check:
Before choosing CBN cutting tools, make sure the insert geometry fits the actual operation rather than selecting a shape only because it is commonly used.
The right combination of grade, shape, and size helps the tool match the machining job more effectively.

When CBN Turning Inserts Can Replace Grinding

Grinding has traditionally been used for finishing hardened parts, but it is not the only option. In suitable applications, hard turning with CBN turning inserts can take over some of the work.

Traditional approach:

Machining → Heat treatment → Grinding → Final finishing
Hard-turning approach:
Machining → Heat treatment → Hard turning → Final finishing
So, what can change when hard turning is suitable?

• Fewer process steps
• Less movement between machines
• High-speed finishing
• Good control over finished dimensions
• Potential to reduce grinding operations
• A simpler production flow

Cubic boron nitride inserts are beneficial when hard-turning materials such as hardened steels are involved, and they are not a blanket substitute for grinding. Workpiece material, hardness, desired finish quality, grade of cutting insert, and cutting conditions should be appropriate.

This is why a test application of the method is essential prior to making an entire production line move.

CBN Cutting Tools Are Not Just About Tool Life

Tool life is important, but it is not the only reason manufacturers look at CBN cutting tools. Provided that it’s application-appropriate, they may assist a smoother, more uniform machining cycle.

Several things that may be considered are

• Fewer changes – Giving longer life, it is possible there are fewer interruptions in the cycle.
• Stable machining – Whereby a suitable grade should deliver more consistent machining.
• High-speed finishing – CBN is also suitable at high speeds where a suitable grade, material, and circumstances exist.
• Hard material cutting – In that the material has been developed for use on the likes of hardened steels and cast iron.
• Less process motion – Using appropriate conditions, the CBN should allow hard turning and minimize movement to differing processes.
• Lower scrap rate – Higher wear life, particularly with the HyperCBN coatings, should translate to less wastage based on tool life.

A Simple Way to Choose the Right CBN Tool

When selecting a CBN insert, one has to first determine the machining task involved. Initially one considers the workpiece material one needs to machine and the hardness of this workpiece; hardened steels, cast iron, or superalloys will require differing grade selections.

Whether one considers that there is going to be a continuous cut or an intermittent one will influence the stresses on the cutting edge. At the end, the size of the insert and its shape depend on the machine, tooling, and workpiece.

After knowing all those components, you will be able to do a test run and observe the tool in action. You can then monitor the machining results and adjust the parameters if needed. This approach helps you select CBN inserts based on the real application instead of choosing a tool based only on the material being machined.

Where CBN Inserts Are Commonly Used

Automotive
CBN is used for machining components such as camshafts, gear hubs, brake disks, and brake drums.

Aerospace
Applications include parts such as landing gear and turbine shafts, where machining demanding materials can require suitable high-performance tooling.

Energy
Bearing races and valve components are among the applications where CBN machining can be useful.

Die and Mold
Hardened tool steel molds can require cutting tools that are suited to high-hardness materials.

Mining
CBN solutions can also be used for wear parts and components such as slurry pumps.

In all these industries CBN tooling is chosen based on the material, its hardness, the cutting conditions, and what the job requires. There is a tendency to choose tooling that suits the task rather than assume a particular CBN grade will do any job.

Why Manufacturers Choose HyperCBN

When you’re choosing tooling for hard machining, product quality is only one part of the decision. Experience, manufacturing capability, application knowledge, and support also matter.

HyperCBN has been in the CBN tooling field since 2005. HyperCBN designs, develops, and manufactures CBN inserts and any other possible CBN tooling. Their available tooling includes boring tools, end mills, milling and end mills, and parting and grooving tools.

Some criteria to investigate could be the HyperCBN selection process of selecting specific tooling for the respective application rather than one option fitting all. Different material, application, grade, and insert geometries are all considered rather than applying the same criteria to any machining applications.

Other items include customization, high-tech production, continuous product development, and customer service. Tooling companies should be able to do selection quicker on difficult machining processes due to the provided provider have clear perception of each possible machining application.

Frequently Asked Questions (FAQs)

1. What are CBN inserts used for?

Used in machining the high-hardness materials such as hardened steels, cast steels, and some high-hardenability superalloys.

2. Selection of the appropriate CBN turning inserts?

Should choose appropriate CBN inserts according to the machining part material and its hardness and cutting conditions of the workpiece and the necessity of insert shape.

3. Can CBN cutting tools replace the grinding process?

It can replace some grinding operations in the appropriate hard-turning situation.

4. What is a Cubic boron nitride inserts?

This CBN cutting material shaped like a cube is suited to extreme applications.

5. How to specify CBN inserts?

When specifying a CBN insert, one should consider the material being machined, workpiece hardness, type of operation, grade, chip form, and index.