Flap discs

Flap Discs are used for:
Intermediate and finishing of welds. Deburring, rust removal and snagging. They are suitable for almost all ferrous & non-ferrous materials.
Excellent for surface finishing

Flap Disc specifications:
A/O Flap Discs - Coated with Aluminium Oxide. For use on alloy steel and low-alloy steel

Z/A Flap Discs - Coated with Zirconia Alumina. For use on High-alloy, stainless and heat treated steels also high tensile non ferrous metals

S/C Flap Discs - Coated with Silicon Carbide. For use on Marble, stone, glass and non ferrous metals.

Typical Flap Discs sizes:
100mm X 16mm (4" x 5/8")
115mm X 22mm (4-1/2" x 7/8")
125mm X 22mm (5" x 7/8")
150mm X 22mm (6" x 7/8")
180mm X 22mm (7" x 7/8")

Types of Flap Discs:
T-27 - Used when working on flat grinding surfaces. Most efficient when used at a 0-15 degree angle.

T-29 - Conical type has an angle excellent for contour and edge work. Best at more dramatic angle of 15 to 25 degrees.

Flap discs are flexible, and will tend to follow the contours of whatever you are grinding. Not much use if you want to get rid of those contours.The trick is angling the disc (see above) and using light pressure.
Even with light pressure they are still quicker than a grinding disc.
As with all sanding products, flap discs are available in various grades from fine to coarse, a 40grit disc will cover most jobs well and remove metal quickly, a finer grade disc is needed for final sanding.

-Tbone