Flap Discs versus Grinding Discs – when to use what?

With so many grinding products available on the market, how does one know what the best choice will be – should I opt for a right-angle grinding disc, or will a flap disc suffice and what exactly is the difference between them and is it enough of a difference to make a difference?

A smooth, well finished metallic surface may be required for either aesthetic or functional reasons. Without a good start, one cannot expect to achieve a good finish and selecting the appropriate product will require some insight into the required end result, be it painted, polished or raw material look.

Considering that the go-to disc for stock removal has always been the rigid abrasive grinding disc, with the use of flap discs becoming more and more popular, one needs to first understand what an abrasive flap disc is. Unlike a traditional resin fiber disc, the abrasive flap disc is a single unit that contains its own backer. Abrasive flaps are arranged radially and in an overlapping format on the face of the backer and glued into place. Flap discs come in various shapes, sizes, and formats with distinctly different shapes.

Shape or Type 27, also known as flat, is best used for blending, smoothing, or finishing applications and suited more to flat surfaces being ideal for deburring and edge grinding applications. Shape or Type 29, commonly referred to as conical, works best for aggressive stock removal, where speed and cutting ability is required. The Type 29 provides a greater contact area with the angle of the disc for improved stock removal on flat surfaces.

Flap discs are manufactured from a range of different grains, each with its own properties suited to specific applications.

Alumina Oxide, red brown in colour, is the most cost-effective grain and usually reserved for light industrial or general-purpose jobs on soft metals and woods.

A more premium, high-tech grain, Zirconia, is blue green in colour and this grain self-sharpens as it wears away during application. Designed to provide high stock removal with fast cutting, this grain offers reduced heat generation with a cooler grind in the material.

Ceramic grains, offering the highest level of stock removal, and mostly red in colour have precision shaped grains that self-sharpen with a unique crystalline structure, which remains sharper and more effective over a longer time period, giving the product extensive longevity. Heat generation is further reduced due to the way that the grain breaks down during usage.

Grinding Techniques manufactures the Superflex flap discs using both Zirconia, and Ceramic grains, with the Premium range featuring a flap disc containing special anti-clogging properties within the ceramic grains specifically manufactured for non-ferrous metals.

Superflex Abrasive flap discs come in 40, 60, 80 and 120 grit sizes and different diameters to fit standard right-angle grinders. Coarser or finer grits are available on request. A coarser grit disc is used when a quicker removal rate is essential and surface finish is less important, whereas finer grits are usually reserved for blending, smoothing, and finishing operations, where surface finish is more important. They are typically used in the latter stages of the process.

Using flap discs carry a few benefits in comparison to conventional grinding discs.

As a flap disc provides a more controlled stock removal application with cooler cutting, less re-working of the piece is needed as discoloration is limited, even on heat sensitive materials where conventional grinding discs could potentially form fine hairline cracks resulting in damage on the piece, a cooler grind from the flap discs can avoid this to a great extent.

Two applications are possible with one product. An angle grinding disc has the tendency to create deep gouges due to the extremely aggressive design. A piece ground with an angle grinding disc will need to be retouched with a secondary product to improve the finish. With an abrasive flap disc, both stock removal and finishing can be done with the same product, at the same time. This reduces down time for disc changes, resulting in a reduction in overall contact time.

Operator fatigue is significantly reduced. Not only are abrasive flap discs substantially quieter than angle grinding discs, but they also create less vibration due to the lower pressure being used during application. Flap discs are lighter, which added to the lowered vibration, puts less strain on both operator and machine.

On the other hand, if you are only looking for fast stock removal and are not concerned by or requiring a smooth finish, then the traditional right-angle grinding disc may well be your best answer. Grinding discs are suitable for metal, non-ferrous and stone applications across a range of machine sizes. The main function of a grinding disc is fast material removal. Various industries utilize grinding discs successfully in their operations such as foundries and engineering shops. Depending on the application a range of grinding discs are available, from the standard Industrial range suitable for mild steels right to the Premium range suitable for high alloy and heat sensitive materials. As with flap discs, grinding discs are available in two shapes; a Shape or Type 27 for general grinding applications and a Shape or Type 28 which is a dome-shaped disc suitable for more aggressive stock removal at an angle which facilitates reduced operator fatigue as the disc design automatically provides the right approach or grinding angle without the need to manipulate the grinding machine.

To decide between a flap disc and a grinding disc one now needs to answer the following question – what does my end product need to look like? If your product needs to be painted, coated, polished and/or be provided raw with a good finish, then the abrasive flap disc is your best option, if you need fast material removal without the need for a smooth surface finish you may want to consider the grinding disc as an option.

In conclusion, the Superflex abrasive flap discs will provide fast, cool grinding regardless of the material. Coupled with the improvement in operator fatigue, the versatile flap disc does look to be the future product of choice.

For more information contact us: 011 271 6400 | info@grindtech.com | www.grindtech.com.