Angle grinders are available in various sizes and hence do the discs. But some discs are available only for specific sizes. While most of the Angle Grinder Discs are produced for 4” models, let’s discuss its types. Before we start, If you haven’t bought your first Angle Grinder yet, let me request you to read our article on Angle Grinder Buying Guide. If you are confused about buying either a 4 inch or a 5 inch grinder, I suggest you follow with this article on, 4 inch vs 5 inch Angle Grinders.
Note: Currently only metalworking discs are discussed.
The Angle grinder’s primary job is to grind metal. And this can be achieved by grinding discs only. These discs can easily scrape off metal with less effort. These are available in various grits. The smaller the grit number, the faster it can grind, but sacrificing surface finish. The higher the grit, the slower it will cut with a better surface finish. The grit numbers generally vary from 24 to 80. Higher grit discs are also available for industrial purposes. Grinding Discs are available in 4. 4.5, 5, 7, 9 inch sizes. In recent years Flexible Grinding Discs have been developed. Some like them, and some do not. You have your try.
Cutting/ Cutoff Discs
These discs are widely used for cutting metal objects. Available for most grinders of 4. 4.5, 5, 7, 9 and even for 14” cutoff saws. As the size increases the thickness increases too. So remember to add this disc thickness to the markings made on objects to be cut.
This disc is an abrasive disc with reinforcement as it is brittle. Nowadays, Metal Cutting Diamond Discs are also available. They are slow to cut but are very clean as they don’t spill aluminum oxide powder all over the place.
For Stainless Steel use, INOX Cutting Discs are used. For Mild Steel both INOX and non-INOX can be used. Generally, INOX indicates that the disc is free from Sulphur and Chlorine which reacts with Chromium content in Stainless Steel.
Cutting disc is used only for straight cuts and not for curved cuts. Non-straight cuts tend to lock up the disc causing kickbacks or disc shatter. Also, this disc shouldn’t be used sideways for de-burring.
The only disc which can be used sideways is the GRAFF Black metal cutting disc.
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The high grit grinding discs do provide a good surface finish. But not better. To make it more appealing, flap discs are used. These discs are made by sanding papers stacked together. Since they are available in various grits, one can easily decide and buy the specific disc for their job. The only drawback of these discs is that the production costs are high and hence prices are also on the higher side. The grits vary from 60 to 240 or even more. These discs can also be used to carve wood and their use is not limited. They are available in 4 and 5 inch sizes. I always recommend buying 4 inch discs as they are much cheaper than 5 inch ones.
Overall, both the grinding and flap discs can execute the same job. For the same amount of metal removal, one single grinding disc equals 5 or more flap discs. This doesn’t mean, grinding discs are always better. In my personal fabrication experience, I use Flap discs more than grinding discs. The main advantage for me is that, even if they get old, they will still grind. I never throw off any of my flap discs. I use them on wood for chamfering, where I can get a good surface finish. Because, since they are old, they scrape less material. This becomes an advantage for woodworkers, during fillet/ chamfer/ edging precision operations.
To grind a weld bead, I use the grinding disc. To finish it, without damage to the surface, I use a flap disc.
There are many types of Buffing discs for Angle Grinders. For stainless steel polishing, Non-Woven buffing discs are available. They do contain minute abrasive particles, which help Stainless Steel to retain its standard Chrome color. They are operated dry without any buffing compounds. They look similar to Scotch-Brite material. The material used in this disc is usually fiber. This disc can also be used to remove rust from metal parts, without any metal loss. This disc was first designed for Bench Grinders before using on Angle Grinders. In the above picture, the brown disc on the left is an 8 inch Bench Grinder Buffing Wheel.
This is a compressed cotton disc. Mainly used for metal polishing. Available in 4 inch and 5 inch sizes. For Automotive polishing Velcro-type polishing pad is used. First, a polishing compound is applied to the metal and then polished using this disc. This provides the surface a mirror finish and polishing liquid applies a protective coating over the workpiece. Both Polishing Compound and Polishing Liquids/ Gels are different. Most of them have fine abrasive powder. Remember! Automotive polishing wax is not the same as other polishing compounds.
Automotive polishing should not be done on Angle grinders. Using wrong polishing liquids and high RPMs rips off the paint. Woolen Polish disc is available, particularly for Automotive polishers. Taking guidance from a professional is highly recommended. But for Non Painted Engine parts, buffing/ polishing discs can be used without any trouble. Ex: To polish Royal Enfield UCE Engines.
PVA Abrasive Disc
These are general-purpose abrasive discs with finer grits ranging from 400 to 3000. Steel can be brought to a chrome finish with these discs. PVA Abrasive discs are also widely used to polish marble, glass, stone, ceramic, wood, and all types of ferrous and non-ferrous metals. People can choose between Sand Papers or PVAs. Because both provide a similar surface finish. In some countries finding Fine Grit, Sandpapers is difficult. And in some, finding PVA Discs is difficult. And some hear about PVAs for the first time by reading this article. Always use this PVA Disc dry. Never use it with any polishing compound. PVA Disc is basically silicon carbide powder bonded with Poly Vinyl Alcohol. Removing paint, rust can also be achieved. The disc will not clog as it is just compressed silicon carbide powder bonded with PVA (Poly Vinyl Alcohol). This disc is also called a Felt-DC Wheel in some markets.
Buy Link: This May not be available online. If you need please Email me, [email protected]
Wire Cup Brush Wheel
This wheel is generally used to remove rust off the materials, to clean the surfaces before welding, remove the spatter after stick welding. There are two types of Wire wheels, one of steel and the other of brass (Technically, it is Steel Wire itself coated with Brass Color). Steel wheels are used on ferrous materials like Mild Steel, Stainless Steel, etc. Brass wheels are used on non-ferrous materials like Brass, Aluminum, Copper, etc. Using steel wheels on non-ferrous materials should be avoided because the steel wires will scrape off the actual material itself instead of removing corroded material or paints. You can also buy Flat type wire wheels instead of Cup type. Twisted and non-twisted cup wheels are also available.
Velcro Sanding Pads
This is a sanding attachment for the Angle grinder. There are two types of Velcro Pads available. One for 4 inch and the other for 5 inch Angle Grinder. Both support the same size Sanding Paper of 125mm (5″). The difference is based on their nut sizes. The 4-inch grinders have M10 Nut and the same type of Velcro Pad should be purchased. The 5-inch grinder has M14 Nut. If you are using this attachment for a drilling machine, I suggest you buy the Angle Grinder Spindle depending on the size of the Velcro Pad. By using this spindle, Velcro Pad can be easily attached to any drilling machine.
The only drawback to this attachment is that during usage only one side of the sanding paper starts to wear and the center area of the paper will be unused. If someone is thinking to buy a Drum Sander, this is the cheapest option available. The Velcro Pad is actually an Orbital Sander attachment. So, you can use Orbital Sander discs.
This Backing Pad attachment is also similar to Velcro attachment except it mounts directly to the center nut itself. In this case, too, the user has to buy the nut according to his Angle Grinder size. Either M10 or M14. The Backing Pad attachment is very versatile compared to Velcro Pad. Because 70% of the sanding disc can be used. The Backing Pads are flexible. In the market, you can buy either Plastic/ Fiber or Rubber Backing Pads. Rubber pads are user-friendly and they operate very smoothly. Plastic pads are not that great when it comes to flexibility. For both Velcro and Backing pads, all types of grit sizes are available ranging from 60 grit to 220 and even more. Finding a 2000 grit sandpaper is very hard in India. Because of the Velcro strip, these sand discs are expensive compared to normal Backing pad discs. Overall, both have their advantages and disadvantages. But anyway, both are very cheap to buy. The user can test each of them and stick with his preferred choice later on.