Selecting the Right Grinding Wheel for Your Application
In a previous article, we took a look into the world of angle grinders to help you figure out which one is the best model for you. To get the best out of that grinder, however, you’ll need to pair it with the right grinding wheel, and that’s what we are going to talk about in this post.
Choosing the right grinding wheel for your application can be challenging. There’s a wide selection of wheels to choose from and the differences between the different types of abrasives can sometimes be confusing. To give you a bit more clarity, we’ve broken down all the characteristics that differentiate grinding wheels and provide a list of the most recommended models.
Grinding wheels explained
Grinding wheels are abrasive cutting tools. The abrasive grains distributed on the surface of the wheel form thousands of cutting points capable of cutting away tiny chips of material. These grains are held together by a bond, in most cases a mixture of selected clays, and separated by pores.
When the wheel is in use, the abrasive grains cut into the material that is being ground, removing the unwanted surface material in small chips. The type of the abrasive, the size of the abrasive grains (or grit), and the type of bond are the three most important characteristics to consider when choosing a grinding wheel.
There are four main types of abrasive grains available for grinding discs. Each type has unique properties when it comes to hardness, strength, fracture toughness and resistance to impact. The choice of the abrasive is inevitably related to the material of the workpiece.
Aluminum Oxide is the most common abrasive used in grinding wheels. It is generally recommended for grinding materials like stainless steel and tool steels, but it can also be used on some high tensile aluminum and bronze alloys.
Harder than standard aluminum oxide with a very sharp abrasive grain, it is often used for grinding gray iron, chilled iron, brass, soft bronze and aluminum, as well as stone, rubber and other non-ferrous materials.
For use in rough grinding applications where high stock removal is required. This grain is associated with high-tech resin bonds.
Ceramic Aluminum Oxide
Often referred to as just “Ceramic”, this is the most modern type of abrasive. This ceramic grain has a unique microcrystalline structure that is self-sharpening. This abrasive is exceptionally hard and strong. It is primarily used for precision grinding in demanding applications on steels and alloys that are the most difficult to grind.
As we mentioned above, grit is related to the size of the abrasive grains distributed on the wheels. The higher the grit size, the finer the abrasive is. The basic descriptions of abrasive types range from coarse to medium to fine. Here’s a basic table of the different kinds of grit sizes.
Grinding wheels with a low grit size are commonly used in applications where the material finish is not important, and the focus is on material removal. On the other hand, fine grit wheels are preferred when finish is a fundamental aspect of the project.
Bond is the material that holds the abrasive grains together so they can cut effectively. The bond must wear away as the abrasive grains wear and are expelled so new sharp grains are exposed. Most grinding wheels are made with vitrified bonds, which consist of a mixture of carefully selected clays. These types of wheels are strong and porous and are not affected by water, acid, oils or variations in temperature.
An important aspect to consider when it comes to bonds is their strength or grade.
Strong bonds, or hard grades, are recommended for soft materials, small or narrow areas of contact, or longer wheel life. Weak bonds, or soft grades, are preferable for hard materials, such as hard tool steels or carbides, for large areas of contact, or for rapid stock removal.
While grinding wheel selection should be based on all the factors mentioned above, finding a universally recommended wheel is nearly impossible. However, some brands tend to be more effective than others. Here are some of our favorites:
Norton is one of the most recognized brands when it comes to grinding wheels. The company has been delivering abrasive solutions for over 100 years and they offer the widest portfolio of grinding, cutting, blending, finishing and polishing solutions for an array of materials. This aluminum oxide coarse model is ideal for applications that require high material removal.
Dewalt is an authority in the field of hand and power tools and they offer long-lasting wheels at an affordable price. This model is ideal for applications that require aggressive grinding action.
Diablo specializes in circular saw blades, reciprocating blades, sandpaper, and bonded abrasives. They offer a variety of solutions for different applications. This wheel cuts fast and is very effective on stainless steel.
Makita is a highly recommended leading brand in the metal grinding landscape. When paired with Makita’s angle grinders, they can deliver impressive results in terms of grind life, stock removal rate and precision.
How to Choose the Right Wheel
After reading all the information above, you might be wondering how to correctly choose the right wheel. The following questions will help you identify the right model for your application:
- What material will you be grinding and how hard is it?
- What stock needs to be removed from the material?
- Work out the shape of the material and the surface finish (or finishes) that are required.
- What type of machine will you be using? (Pay attention to its power and its conditions.)
- What wheel speeds and feeds will be involved?
- Determine the size and hardness of the grinding contact area.
- Will your grinding operation be a wet or dry process?
- What is the severity of the grinding required?
- What is the dressing method?
In the end, selecting the grinding wheel is a process that requires a lot of time and thought, but if done right, can lead to great results.
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