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Which discs should I buy for cutting metal and steel lengths?

Which discs should I buy for cutting metal and steel lengths?



Rear of a metal cutting disc
5″ 125mm Metal Cutting Disk Rear

Their is really only one way when cutting metal and steel with any precision. You have the choice of an oxyacetylene torch for a rough, close enough cut, particularly for thick steel plate. Or you can buy different size metal cutting discs, depending on the tool you are using, to cut the material with precision. Metal cutting discs are made of treated abrasives that in their bonded form are harder than the metal or steel you are likely cutting.  The tool is quite simply the only determinate on which size metal cutting disc you might purchase.  The bigger the tool, the bigger the metal project you can cut.  Metal cutting and grinding discs must be made to standards. They operate at high speed and the disc degrades as the metal makes contact with the material. The metal cutting disc shrinks in size as the material is cut. How fast the disc shrinks and degrades is subjective and there are no single tests between brands that determine whether one is any better than another.


Some metal cutting disc brands have been around for many years and are so widely distributed they are assumed to be the best products. The difference in the products is primarily the abrasive ingredient and how it is moulded and bonded within the disc manufacturing process. The two most common mineral ore ingredients you will see advertised in metal cutting discs is zirconia alumina or aluminium oxide. These two products in particular after having gone through heat-intensive processes will suitably cut through metal while wearing minimally. How quickly the disc wears is the general measure of the quality of the disc and additionally the price differentiator.  So which do you buy, the aluminium oxide or the zirconia alumina disc?



125mm Metal Cutting Disc
125mm Metal Cutting Disc

They are both well performing for cutting metal and steel however, they can still not be as they seem.

Aluminium Oxide – definitely the most common ingredient found in most metal cutting discs.  Colour is not a good guide, look for labelling on the front of the disc. If their is no labelling it is very hard to tell the core ingredient. This is why people stick to a brand where they know the way the disc functions or perhaps the ingredient. Can be red, brown, green, blue, yellow or black on the underside. The colour is usually indicative of the grinding aid or lubricant bonded with the disc. Aluminium Oxide is considered a good starting point for most metal and wood applications.


Zirconia Alumina – you will normally see this labelled as simply Zirconia.  This product is normally coloured green or blue on the underside. Zirconia can be manufactured or exist in a raw state. All our cutting disc variants are made from German VSM Zirconia, widely considered the best raw material for cutting metal and steel. The Zirconia grain is known for its hardness and is suitable for medium to coarse applications on metal.



Metal fabricators, steel fabricators and those who work with metal usually find a brand they like and stick to it however, there are often just as good equivalents.

You’ll also see marketing terms sneak onto the face of the discs too – terms like ULTRA INOX, Aluminium Oxide/Zirconia Alumina blend confuse the general user.

INOX means nothing more than stainless steel. Stainless steel is the hardest metal to cut due to the addition of nickel to the metal construction process. Anything made of stainless steel is harder to cut. Of course, there are grades of stainless steel too, the lower grades are harder to cut than the higher ones. If you’re cutting mild steel it’s safe to buy a disc made of Aluminium Oxide or Zirconia. With so many brand alternatives than ever, competition has brought not only the price down but the technology up. A good quality disc made of either material will cut through all types of metal including aluminium, rebar, sheet metal and other mild steels.




Metal cutting disc size is relatable to the tool you are using. Air, electric or battery-operated tools can be 3″, 4″, 5″, 7″, 9″ or 14″. The smaller discs for the smaller metal cutting tasks, the larger products for the larger tasks. Air tools on die grinders can have even smaller size cutting discs. The most common type of tool though is an angle grinder. Angle grinders are great for portability and cuts that don’t require precision. Drop saws will cut through angle or boxed iron, generally the larger tasks, and can cut through with precision. You will generally find 4″ tools used by DIYers. Business tends to use multiple variants however, none of this is set in stone.



5″ 125mm Metal Cutting Disk Profile

Metal cutting disc thickness varies too. The thinnest disc in the smaller 4″ & 5″ sizes are 1 and 1.6mm.  For everyday work on metal up to 5mm choose a 1mm or 1.6mm disc. It will cut through cleanly with a degree of precision that depending on your skill will require only a small amount of squaring.  For metal greater than 5mm, consider using a larger tool that can accommodate a larger metal cutting disc. Something like a 7″ or 9″ tool. It will cut through quicker and is easier for you to work with. Where you require precision cutting for a metal project consider using a drop saw. They are far easier to use for a straight cut and they allow for angled cutting.  The use of metal cutting discs to cut metal is harder with smaller tools and discs than with the larger ones however, the smaller tools are more flexible.


Safety is paramount when using metal cutting tools whether that be air, electric or battery-operated devices. There are many reported cases where consumers have tried to use a tool with the wrong size metal cutting disc. They have generally removed the guard around the angle grinder, attached a larger disc and come to mischief. These are devices that operate at high speed able to cut through the hardest metals.  Safety glasses and gloves, as well as correct use of the tool, are very important. It is important when using the angle grinder to let the cutting wheel do the work, you should be applying even and constant pressure to cut through the material.  There are some great videos available on YouTube showing how to use an angle grinder safely, here’s one we found based out from weld.com based in the US.



Metal cutting with an angle grinder
Angle Grinder with Cutting Disc

At Zip Tie Guy we have sourced a manufacturer who produces cutting discs using Zirconia Alumina with  Silicon Carbide, developed in Hanover, Germany. The raw materials are then sent to their own plant in Europe where they form the base ingredient for all of the different types of products we sell. Combined, these materials produce products that provide the hardness and cutting required against the toughest metals.