Although any of them can work, both a grinding disc and a floppy disk can suit quite different purposes, when it comes to iron grinding targets. What is the best way to sharpen an iron? We will highlight relevant points in the following lines.
A floppy disk or a grinding disc?
As mentioned, both a floppy disk and a grinding wheel can be quite similar, as they can be used as part of larger grinding machines designed to sharpen and reshape a metal. Traditionally, grinding discs have been designed for the purpose of removing "unnecessary" materials (grinding), as well as for preparing surfaces for certain operations (perhaps painting). They can be coarser and faster in sharpening compared to a floppy disc (made of zirconia), and yet - they do not exactly leave the most refined finish. On the other hand, a floppy disk can help achieve a more balanced and smooth finish.
Grinding disc for efficient and fast material removal
Therefore, if condensed - a grinding disc can be used to sharpen and remove materials from metal and stone. It can be used to sharpen pieces of steel, in preparation for welding them. If you want a strong and fast result, a grinding disc can help in many cases. And yet, the final finish may seem unbalanced, as here and there some pieces may be more prominent than others. So a grinding disc can work well if you want to get rid of large and fast pieces, but not necessarily if you want the most balanced and even finish (in terms of surface visibility).
Floppy disc for finishing and refinement
A floppy disk can come in all sorts of shapes and sizes, and yet some will say that the ceramic floppy disc is the most effective, and can fit all types of metal - as well as aluminum. There are types of floppy disks, which can be made of aluminum oxide (aluminum oxide). Floppy discs are considered slower in metal grinding (compared to a grinding disc) and yet they will indeed give a more balanced and refined finish. This can be especially suitable if you want to paint the metal after sharpening it.