CBN Grinding Wheels: A Comprehensive Guide

When you go to sharpen a tool, how often do you discover that you need to replace your diamond grinding wheel? Is it happening too frequently? You may use your wheel more than most, but what if that's not the case? You may simply lack the proper wheel for the job, causing your grinding surface to wear out faster.

Because of their hardness, many people believe diamonds are the best grinding material, but this is not always the case. CBN grinding wheels might be a better option. In many cases, they last longer and can save you money over time by requiring fewer replacements. Continue reading to find out why a CBN wheel might be a better fit for your operation.

Choosing a Grinding Wheel

What you need to grind should always be at the forefront of your wheel selection process. Apart from that, there are three major factors to consider when selecting a grinding wheel:

The abrasive material that enables your grinding wheel to work.

The adhesive that holds the abrasive granules to the wheel.

The abrasive granule concentration ratio bonded to the wheel

By adjusting each of these variables, you can tailor grinders to your specific needs. Remember that the best abrasives, bonds, and concentration ratios for your needs are all determined by the material to be ground.

Abrasive Granules

On grinding wheels, a wide range of abrasives are used. These materials are broken down into very small grains and bonded to the wheel.

Small pieces of the granules chip off as you use the grinding wheel. This chipping action keeps the grinding face of your wheel sharp.

Grinding Wheels Made of CBN

Cubic Boron Nitride, or CBN, is the grinding material used in a CBN grinding wheel. Cubic Boron Nitride is a highly abrasive material. Super abrasives, as the name implies, are more powerful than standard abrasives such as aluminum oxide and silicon carbide. CBN is best suited for grinding hard metals such as:

Steels with a minimum hardness rating of 45Rc

Irons, both cast and wrought

Nickel alloys

It is only second in hardness to diamonds.

CBN vs. Diamonds

You may be wondering why you would use a CBN grinding wheel when diamonds are so much harder. The simple answer is that diamonds aren't designed to work with hard metals. Diamonds are ideal for grinding more delicate materials such as glass, quartz, and ceramics.

CBN does not react chemically with iron. When grinding most hard metals, CBN's lack of reaction allows it to remove more material and last longer than diamonds.

A grinding wheel with a longer life cycle has several advantages:

Fewer wheel swaps

Reduced downtime

Reduced maintenance costs

Better wheel performance results from more controlled wear rates.

CBN is also superior to diamonds for grinding hard metals due to its extremely high thermal conductivity. It can withstand temperatures of up to 1,000 degrees Celsius before degrading.

Even diamonds have lower thermal conductivity than CBN, which is the best natural heat conductor.

CBN vs. Traditional Abrasives

Hard metals can be ground with conventional abrasives, but the wheel will wear out quickly. As a result, a CBN grinder is typically a better fit. Consider some of the advantages of using CBN over abrasive grains made of ceramic or silicon carbide.

Increased life expectancy

Improved consistency

Perfect cutting edges

Work is less likely to burn or otherwise be damaged.

CBN’s high thermal conductivity rate helps out here too. It is why this material can promise less damage while grinding.

The Bond

A grinding wheel's adhesive bond does more than just keep the granules in place. Additionally, it serves as a shock absorber and promotes even wear on the grinding face.

Organic resin and vitrified bonds are the two types of bonds that are most frequently used with CBN grains.

Bonds in Organic Resins

Natural substances called organic bonds are used to hold abrasive granules to a grinding wheel. Compared to metal and vitrified bonds, organic bonds are more effective shock absorbers. When it comes to CBN grinding wheels, resin-based bonds are the most prevalent organic bonds.

The resin is the most effective at absorbing shock among the available organic bonds. CBN grains and a resin bond work together to create a wheel that can remove a lot of stock at once.

This kind of wheel is ideal for labor-intensive tasks like conditioning hard metals or removing whole chunks of steel with abrasive cuts. For fine work, such as diamond grinding, resin, and CBN can be combined.

With a different kind of bond, the same work could be accomplished, but the bond would dissolve more quickly under shock. Uneven wear results from the bond breaking down too quickly, which compromises the durability of the wheels.

Read this article to find out more about the variations between CBN and Diamond resin wheels.

Vitrified Bonds

Flux and ground clay that has been superheated are the main components of a vitrified bond. The rigid but incredibly strong vitrified bond grinding wheels. This means that it is not a good idea to use them for rough work like you would with a resin bond.

Although a vitrified bond with diamond grains is more frequent than one with CBN, this combination is still useful for grinding materials like alloy steels.

If water, oil, or acid will come into contact with the wheel, you might also think about using a vitrified bond. These substances barely have any impact on this kind of bond.

The most significant advantage of a vitrified bond is that it can be redressed and reused when it wears out. Because you won't have to replace your wheels as frequently, this can save you a lot of money.

Ratio of Concentration

The volume of abrasive granules to bond space on a grinding wheel is referred to as the concentration ratio. A higher concentration ratio means a more efficient grind or G-ratio.

When it comes to CBN, you usually want the highest G-ratio possible. When grinding softer materials, a lower ratio is preferable.

An Action Superabrasive representative can assist you in determining the best concentration ratio for your grinding requirements.