A flap disc is a tool that remove metal from metal surfaces. When using a flap disc, it is critical to choose an correct flap disc, as using the wrong flap disc will damage the metals that you are working on. Flap discs are defined by they’re grit, the grain chemistry of the flap disc, the shape of the flap disc, and its diameter.
Understanding these features will allow you to select the correct flap disc to performing the necessary job on your metal. Flap discs has three different grit sizes: coarse, medium, and fine. Coarse grit flap discs will remove metal at a faster rate then medium or fine grit flap discs.
How to Choose and Use a Flap Disc
If you are removing metal from a metal surface quick, use coarse grit flap discs. Fine grit flap discs will remove the least amount of metal from metal surfaces. You use fine grit flap discs when you require a smooth metal surface.
A fine grit flap disc will not be effective in leveling a weld on metal. Use coarse grit flap discs to remove bulk metal from metal surfaces. Switch to fine grit flap discs once you have leveled a weld.
Fine grit flap discs will produce a smooth metal surface. Flap discs have different grain chemistries. The two most common grain chemicals are aluminum oxide and silicon carbide.
You use aluminum oxide grains on carbon steel and may damage other metals. For instance, if you use aluminum oxide grains on stainless steel, the aluminum oxide grain will rust the stainless steel due to metal contamination. Use zirconia and ceramic alumina grains for metal grinding applications that require high level of metal pressure.
You use silicon carbide grains on non-ferrous metals like aluminum. If you use the wrong grain chemicals on metal, the metal will melt into the flap disc. This process is called load the flap disc.
When the metal melts into the flap disc, the metal will clog the flap disc, and the clogged flap disc wont be able to effectively cut the metal. Flap discs have three different shapes: flat, angled, and round. Flap discs have a flat blade shape that allows them to have maximum contact with the metal that is being ground.
You use flat flap discs to blend metal welds so that the welded portion is flush with the remaining metal. Angled flap discs are used when working on metal that have a certain contour. Angled flap discs allow metal work to be performed at a steeper angle than would be possible using a flat flap disc.
The angle of the flap disc must be set correctly so that metal is ground smooth without being gouged. Flap discs come in different diameter. The larger the diameter of the flap disc, the less rpm that it can reach.
The maximum rpm that a flap disc can reach is printed on the flap disc. The rpm of the metal flap disc should be higher than the no-load speed of the metal grinder. If you spin the metal flap disc at a rate faster than its rating, the metal grinding tool will become a hazard to the worker.
When using a metal flap disc, apply the correct amount of pressure to the metal. Many people believe the more pressure you apply with the metal grinder to the metal flaps, the faster the metal will be ground. This isnt true.
If you apply too much pressure to the metal, the metal will bake into the metal flap disc and the metal will wear out the flap disc. Use medium pressure on metal when using a metal flap disc. Do not let the metal grinder sit in one spot on the metal.
The metal will heat up because the metal grinder is in one spot. This will discolor the metal. The next time you use a metal flap disc, use a systematic approach to cutting the metal.
Do not jump from coarse flap discs to fine grit flap discs. Instead, use one grit size until the metal is ground down, and then move to the next grade of the flap disc. When grinding metal with a metal flap disc, ensure that the passes of the metal flap disc overlap by half the width of the metal flap disc.
This will ensure that no line will be left on the ground metal. By using the correct grit size, grain chemicals, shape, and pressure, you can effectively finish your metal surface.
