A great weld begins with proper preparation, and proper preparation begins with a clean cut. Cutting metals requires skill and knowledge in which cutting wheel or disc to use for the task at hand. The ideal type of disc for a specific job will be largely dependent on the type of material being cut. But at the end of the day, nothing beats proper technique in terms of productivity and cost savings.
Welders almost always prefer a cut line that’s consistent and smooth to make a strong, clean joint with the least filler metal possible. In order to do that, the cut will have to be performed with the sharpest and fastest method possible, so that you avoid smearing and contamination. This can be very important as contamination and a smeared surface can compromise the fusion of the joint during the welding process.
The biggest challenge welders face when picking the right cutting discs for the job is whether smoothness and speed are a priority, or whether durability is more important. Cheaper cutting discs usually have softer bonds which offer a fast, smooth cut. But due to the fact that the bond is softer, the wheels are less durable. Conversely, harder wheels are more durable, but cut more slowly. The key to picking the ideal cutting discs is to find a good balance between durability, speed and cost. There are three cutting grains that are typically used for cutting wheels: ceramic alumina, aluminium oxide, and zirconia alumina.
Aluminium oxide discs use a soft bond that isn’t very resistant to heat, which results in fast, smooth and easy-to-control cuts. They’re the least durable type of the three, but are the most economical one and have a high initial cut rate. That being said, these wheels are great for cutting mild alloys like carbon steel. Plus, aluminium oxide discs have an increased cut rate, are more durable and have a low cost of use.
Ceramic alumina is designed to self-sharpen, and it is very durable. However, they’re expensive due to the fact that they’re manufactured with 1000s of fracture points designed to chip and fracture when in use, which makes them self-sharpen instead of becoming dull. With that being said, ceramic alumina discs maintain their cut rate and sharpness for about 75% for the majority of their lifespan before the user will feel a decline in their performance.
Zirconia alumina is tougher and harder than aluminium oxide, but less so than ceramic alumina. This type maintains sharpness better than aluminium oxide and it is more resistant to heat, which contributes to it creating harder bonds and having a longer life-span. These discs provide great overall value as they don’t need to be replaced all that often, thus minimising costly operator downtime and reducing product changeover.