Cutting Disc Standard Sizes Explained

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One of the most popular uses for angle grinders and powered saws is cutting particularly hard or resistant materials. Exactly what you will be cutting should determine what type of cutting disc to choose – cut off discs for metal or stone, diamond disks for slate, marble and abrasive materials, etc. However, each type of disc comes in a range of sizes.

Standard sizes include:

  • 115mm cutting disc (4.5 inches)
  • 125mm cutting disc (5 inches)
  • 150mm cutting disc (6 inches)
  • 180mm cutting disc (7 inches)
  • 230mm cutting disc (9 inches)

The measurement refers to the diameter of the cutting disc itself.

The most common size for DIY applications is the smallest – 115mm or 4.5 inches. All kinds of abrasive, grinding and cutting discs are available in this size.

Likewise, the most common angle grinders are smaller, lighter units which can only accept cutting discs up to 180mm (7 inches). They are commonly used to cut rebar, to sharpen blades of other tools, or for other light purposes. Smaller grinders and cutters like this often operate at very high rotational speeds, often topping out at 10,000 RPM or higher.

Angle grinders and cutters which can take the largest sized cutting discs – 230mm (9 inches) and up – are generally used for heavy industrial purposes, such as cutting paving slabs, steel beams or large pipes. These larger discs tend to be used at lower speeds than the smaller types, as it can take quite a bit of torque to get them moving. Large grinders like this rarely operate above 6000 to 6,500 RPM at the high end. However, even the largest grinders still accept all cutting disc standard sizes.

Note that you should never attempt to use a larger disc than your cutter was designed to handle, and should never operate it without the guard properly affixed.

Is there a practical difference between cutting disc standard sizes?

Yes, definitely. On the one hand, there is simple utility – a smaller disc does not extend very far form the axle driving the disk itself, and therefore cannot cut as deeply into a material as a larger cutting disc. If you need to cut, say, a 3 inch concrete paver, you would have difficulty using a 115mm (4.5 inch) cutting disc, as it barely extends 50mm (2 inches) from the cutter. A 180mm (7 inch) disc could do the entire cut in a single pass.

Conversely, using too large a cutting disc can be awkward, inconvenient or even dangerous. If you only need to cut a 2mm aluminium panel, a 115mm (4.5 inch) cutting disc is plenty, even if your cutter could mount a 180mm (7 inch) disc.

A final consideration is the torque required to drive the cutting disc – many smaller cutters and grinders are physically capable of mounting 150mm (6 inch) or even 180mm (7 inch) discs, but might not be able to supply enough torque to get the cutting disc up to full speed or to maintain that full speed when cutting hard materials. A slower spin can lead to a slower cut, or worse a messier one. In general, it is advisable to use the smallest cutting disk that will work for any given job, unless you have a very large cutter.

Cut most materials with this one disc…

While most cutting disc are used for only one material, Multimax Direct sells a Rustung all-in-one cutting. This disc will cut steel, stainless steel, aluminium, PVC and concrete without any reduced performance. Click the button below to find out more.