What is a Flap Disc Used For

Choosing the right angle grinder attachment for the job is essential to get the desired results. And, when it comes to choosing the best metalworking tool, flap discs are most fabricators' first choice. A flap disc is a coated abrasive tool used to conform and shape metals. This tool is widely used in welding, machining, heavy-duty machinery, industrial maintenance, agriculture, and food production industries.

What is a Flap Disc?

A flap disc is an abrasive tool made of overlapping abrasives pads called "flaps", these flaps are glued on fiberglass or metal, or plastic plates to serve as angle grinder attachments. In various applications, a flap disc is less expensive and equally effective as a grinding wheel. Flap discs are the more popular because of their fast stock removal as well as the ability to grind, mix and finish in a single use.

Flap discs are versatile, lightweight, easy-to-use, and convenient surface finishing tools. When used to smooth welds after grinding wheel, standard flap discs last up to 25 times longer than aluminum oxide resin fiber discs. They can grind and finish at the same time. For that, you simply have to apply more pressure for a more aggressive grinding and less force for a better finish.

The common application of flap discs are: 

Major Components of Flap Disc

Flap Discs are designed with six specific considerations in mind, and they are as follows

1. Disc Shape: Flat, Conical, and Compressed

Flap discs are mainly available in three common shapes.

Flat Flap Disc or T27 Disc- As the name suggests, these are used on flat surfaces for edge grinding and deburring.

Conical Flap Disc or T29 Disc-  These discs are perfect for surface conduct and aggressive grinding. They are also used for heavy stock removal in different grinding applications.

Compressed Flap Disc- This disc can perform both edge grinding and deburring as well as equally effective for heavy weld removal.

2. Bonding and Backing Materials

Poly-cotton fabric and polyester fabric are the two most common bonding and backing materials used in flap discs.

3. Backing Plates: Fiberglass, Plastic, and Metal

Flap disc backing plates are typically made of three main components: plastic, metal, and fiberglass.

4. Flap Density

The total amount of abrasive area used by the flap on the disc is known as the flap density. The number of flaps used, the angle at which they are used, and the space between flaps all affect the size of the abrasive area. Low-density flap disc is good for heavy-duty applications and fast stock removal, while high-density flap discs are perfect for working on curved and irregular surfaces.

5. Grain Types

Flap discs are designed with different types of abrasives including ceramic, zirconia, and aluminum oxide grains. You can choose the grain material according to your application requirement.

6. Abrasive Grit and Disc Size

Abrasives are available in various grit range from coarse, to medium and fine. A high grit number means a small abrasive grain. Similarly, a low grit number means a large abrasive grain. For fine abrasive products choose high grit or small grain size. Flap disc with coarse abrasive grit is perfect for heavy stock removal and aggressive grinding. And, flap disc with medium or fine abrasive grit is perfect for deburring, mixing, and finishing applications.

Why Use a Flap Disc?

Some specially designed industrial flap discs can remove up to five times more material (with less workpiece gouging) than a grinding wheel. Flap discs are used for several reasons, as they are small in size, lightweight, easy to handle and store, low downtime for product changes, low vibration, and make low noise. When choosing the right flap disc, it is necessary to understand all the important factors.

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