How to choose the right abrasive for your sheet metal

Different materials and applications require different abrasives. But how do you choose the right abrasive? In this blog, we will give you an introduction to the right abrasive for your intended application.

Using the right kind of abrasive for specific applications is often overlooked. However, these are very important tools, indispensable in every machine shop! Poor weld preparation, time-consuming deburring operations, surface qualities that do not meet the intended specifications are just some of the problematic results when the wrong abrasive is used.

But with thousands of product options, choosing the right abrasive belt, top brush or disc for this fundamental step in sheet metal working can be quite challenging. And since deburring, finishing and polishing are often the final operations for many work pieces, using the wrong abrasive can be a very expensive mistake.

Use the right abrasive for your workpiece

Despite the great variety of shapes, grits and types of abrasive available, we can group them into either bonded abrasives (brushes), coated abrasives (sandpaper, belts and discs) or non-woven abrasives (flap brushes). All these abrasives work in the same way, basically using sharp, pointed stones to remove metal from a workpiece.

The material and shape of the workpiece are decisive in determining the type of abrasive to be used. In general, aluminium requires a different abrasive than iron, and iron needs a different abrasive than steel. How do you know that you have the right abrasive for the job? The amount of material to be removed plays a role. Weld preparation requires rougher abrasives, whereas finishing requires finer abrasives. Both may require a different type of abrasive, regardless of the material of the workpiece.

For most parts, these "grains" fall into one of the following categories:

Aluminium oxide

Aluminium oxide crystals, also known as corundum, are available in white, pink and brown, and differ mainly in hardness and purity. Alumina is one of the most commonly used abrasives and offers a cost-effective, predictable solution for a wide range of applications.

Silicon carbide

Silicon carbide crystals are hard, thin and very sharp - the only materials harder than silicon carbide are diamond and cubic boron nitride. The sharp silicon carbide grain gives the surface of workpieces a shiny finish. Unfortunately, the hardness and shape of this grain also make it brittle, so although it cuts quickly, it also tends to break down a little faster than other abrasives, especially under extreme forces. Silicon carbide abrasives are therefore best suited to finishing operations such as grinding aluminium and stainless steel.

Zirconia aluminia

Zirconia aluminia is actually aluminium oxide that is hardened with zirconium oxide. This makes it one of the most wear-resistant abrasives. It is ideally suited for long-term work on harder steels. Due to the self-sharpening effect of the zirconia aluminia, combined with the high hardness and sharpness of the abrasive grain, this tool achieves a high degree of removal and a long service life. It offers the excellent solution for deburring sheet metal where a stronger edge rounding is required. Particularly applicable to hard and tough materials such as stainless steel.

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5 Practical Tips for Working with Abrasives

Choosing abrasives is complex and should not be taken lightly. Here are some important points to consider when choosing.

1. Look out for "cheap" abrasives. They are rarely a bargain and will only lead to more wear and tear, higher labour costs and possibly discarded parts.
2. When in doubt, use a finer grain during the start-up. You can always go for a coarser grit afterwards. If the grit is too rough at the start-up, it will create a surface that is too rough than desired. Reversing this process afterwards is also very time-consuming and will increase the production time, resulting in a lower profitability of the work.
3. Be consistent in the use of each abrasive. Develop a process plan that balances speed of pass with workpiece quality. And stick to it.
4. Make time to test each new abrasive to determine how long it should perform and how much material it can remove in a given period. Document these values as part of your work instructions. Don't be afraid to try something new.
5. Using an abrasive for too long will lead to an unpredictable product quality. However, not using an abrasive long enough can lead to higher costs when it is discarded too quickly.

So the next time you need to grind or polish a component, don't just pick up the 80 grit abrasive belt that is initially available. Instead, talk to your supplier about what is best for your application.

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