Choosing your Abrasive Flap Disc
25 Years ago nobody knew what an abrasive flap disc was. Today they are everywhere in the world of metal fabrication.
Dependent on the product selected abrasive flap discs can now offer everything from aggressive and consistent stock removal through to fine finishing, pre-polishing and now even mirror polishing solutions. So given the benefits of flap discs, how do I choose the right disc for my metal fabrication application?
Flap Disc Shapes
Flap discs are designed for use on angle grinders allowing them to work at a shallow angle or even flat to the metal surface. The angle at which the disc is presented to the workpiece will change how aggressive the grinding action is.
To assist with this three types of flap disc are now commonly made:
Conical shaped discs, flat faced discs and flat faced discs with a flexible edge.
Flap Disc – Flat Construction
Flat faced discs are generally preferred for finishing or more controlled grinding applications where a lower grinding pressure is applied to the disc.
Conical Disc – Beveled Edge Construction
Conical or bevel edged flap discs are generally preferred for high aggression applications and are by far the most commonly preferred shape of flat disc on the market. Operators believe that having a conical edge to the disc makes it easier to have a flat grinding face in direct contact with the metal fabrication.
Plastic or Glass Fibre Backing on the Flap Disc?
Originally flap discs were all supplied with an aluminium backing plate but as the discs became more commonly used the glass fibre backing has become the standard. With a semi rigid backing it allows for high aggression grinding whilst allowing some control.
If greater control and/or reduced vibration is required then it is worth considering the plastic backed flap discs which increase the control and conformability of the flap disc but they will reduce the overall grinding power slightly.
Types of Abrasive
Apart from choosing the size of the abrasive grain the most important question is which type of abrasive grain will give me the best cut / life / cost ratio. Zirconia discs are perhaps the most common disc on the market presently. There is however a new kid on the block with the ceramic aluminium oxide flap discs which are the future of power grinding.
Ceramic alumina: This technology gives a great cut under high pressure grinding applications. Early iterations of ceramic flap discs had a great initial cut but then glazed over. This is not a problem with the latest generation of ceramic abrasives. In 40 and 60 grit forms we recommend ceramic grain grinding on steel, stainless steel and aluminium as well as on high alloy metals such as waspalloy.
Zirconia alumina: Good quality zirconia flap discs are a high quality blend of zirconia and aluminum oxide grain which provides an excellent cut vs cost ratio. They are traditionally supplied for general steel grinding applications.
What Grit Size Should I Use?
I need a disc where I just need to remove stock: 40 grit
I need good stock removal but I may need to refine the finish afterwards: 60 grit is a good starting point
Lighter weld removal and shaping only: 80 grit will be the right disc for you.