What is the difference between cutting and grinding?

You pick up your angle grinder, a versatile and powerful tool. But in your hand are two wheels that look similar yet serve entirely different functions. Using the wrong one can ruin your workpiece, destroy the wheel, and create a serious safety hazard.

The primary difference is their purpose and design. A thin cutting wheel is used to sever or slice through a material. A thick grinding wheel is used to remove surface material to shape, smooth, or clean a workpiece. They are not interchangeable.

This question gets to the very core of what we do at my factory, Reliable. For almost 30 years, we’ve engineered abrasive tools¹, and the distinction between cutting and grinding is the most fundamental principle we teach. It’s not just about a difference in name; it’s about physics, safety, and efficiency. Understanding this difference ensures you get the job done right, safely, and without wasting time or materials. This knowledge is the foundation of professional metalwork².

Is grinding and cutting the same?

Looking at an angle grinder in action, both processes seem violent and fast. It’s easy to assume they are just two versions of the same thing, but this assumption leads to poor results and unsafe practices.

No, they are fundamentally different actions. Cutting is a linear severance using the thin edge of a disc to split a material in two. Grinding is a surface action, using the face of a thick wheel to wear away or abrade material over a wider area.

The goal dictates the process. When you need to cut a piece of rebar, your goal is simple: separation. You want to make one piece into two pieces as quickly and cleanly as possible. The tool for this is a thin cutting disc³. Its minimal thickness reduces friction and removes the least amount of material necessary to make the split. When you need to smooth a weld bead on that same rebar, your goal is entirely different: refinement. You need to remove excess material from a surface to make it smooth and level. This requires a thick, durable grinding wheel that can withstand pressure across its face. Confusing these two goals and their corresponding tools is the first step toward a failed job.

The Action and the Goal

Is grinding a cutting process?

This question creates a lot of confusion. In a university lab, the answer is yes. But in a real-world workshop, thinking this way can be misleading and even dangerous.

Technically, yes, grinding is a multi-point cutting process where millions of abrasive grains act as microscopic cutters. However, for all practical and safety purposes, you must treat it as a separate process from slicing with a cutting disc. The tools and techniques are not the same.

From an engineering perspective, each tiny particle of aluminum oxide or silicon carbide in one of our grinding wheels is a microscopic cutting tool. As the wheel spins, each of these millions of "tools" shears off a minuscule chip of metal. So, academically, it is cutting. However, this definition is not helpful for the operator on the shop floor. For safety and efficiency, you must focus on the macro action. The macro action of cutting is severing. The macro action of grinding is abrading. If you think "I am cutting" while holding a grinding wheel, you might be tempted to use its edge to try and slice a part. This is a very slow and inefficient way to work. If you think "I am grinding" while holding a thin cutting disc, you might apply side pressure, causing it to shatter. In our business, we always stress the practical difference over the academic one.

Is a grinding wheel the same as a cutting wheel?

They both fit on your grinder and are made of abrasive materials. It’s an easy mistake to assume they are functionally identical, but this mistake can cause a catastrophic failure of the wheel.

No. They are constructed completely differently to handle different forces. A cutting wheel is thin and designed only for force on its edge. A grinding wheel is thick and heavily reinforced to withstand the high side pressure of surface grinding.

As a manufacturer, this is where we focus most of our engineering. The integrity of the wheel is everything. A cutting wheel⁴ (often called a Type 41 or Type 1 disc) is thin, typically 1mm to 3mm. It’s designed to slice with minimal friction. While it has internal fiberglass reinforcement⁵, it’s not built to handle lateral, or side-to-side, pressure. Pushing on the side of a cutting wheel is the fastest way to make it explode. A grinding wheel (often a Type 27), on the other hand, is much thicker, usually 6mm or more. It contains multiple layers of fiberglass reinforcement specifically to give it the structural strength to handle immense lateral forces as you press its face against a workpiece. They are two specialized tools built for two different physical tasks. Using one for the other’s job is asking for trouble.

Construction at a Glance

Can I use a grinding wheel to cut?

You need to make a cut, but the only thing you have is a new grinding wheel. It seems powerful enough, so what could go wrong? It’s a tempting but flawed idea.

You should not use a grinding wheel for cutting. Its thickness creates massive friction and heat, resulting in a very slow, sloppy, and burned cut. It puts extreme strain on your grinder’s motor and is far less safe than using a proper cutting disc.

This is purely a matter of physics and efficiency. A thick, 6mm grinding wheel must remove six times more material to make a cut than a 1mm cutting disc. All that extra material removal⁶ translates into extreme friction. This friction generates a huge amount of heat, which can damage the temper of your workpiece and scorch the metal. This process is also incredibly slow and puts a heavy load on your angle grinder’s motor, potentially burning it out. I once consulted for a small fabrication shop that was using our grinding wheels to notch steel pipes. The process was slow, the pipes were discolored from heat, and they were going through wheels and grinders at an alarming rate. We switched them to our thin RL cutting discs, and it cut their process time by over 75% and eliminated the quality issues. It was a perfect lesson: using the right tool isn’t just safer; it’s more profitable.

Conclusion

Cutting severs material with a thin disc; grinding shapes surfaces with a thick wheel. Always use the right tool for the job to ensure safety, quality, and maximum efficiency.