Flap Discs

Flap discs are primarily used to remove weld (or bead) seams however, they can also be used for a variety of other applications including:

  • Cleaning flash from molds and castings
  • Removing rust
  • Edge grinding
  • Deburring

Flap discs are primarily made of zirconium or ceramic. They are a preferred choice over grinding wheels for their efficiency, speed, and precision capabilities. Flap discs are easier to use because they produce less vibration during operation, allow for a better finished product due to a reduced risk of gouging, and decrease the risk of heat discoloration because of their cooler operating temperatures.

Flap Disc Shapes

Flap discs come in two shapes, 27 and 29, and are available in “Standard” (thin) density and “Hi” (thick) density.

Shape 27 flap discs are available in Standard and Hi density and have flat face profiles. They have added thickness since the flaps are not compressed, providing a more cushioned effect for finishing applications. They are ideal for grinding, blending, or finishing irregular and flat surfaces.

Shape 29 flap discs are available in Standard and Hi density and have an angled face profile. The “built-in” grinding angle is best for aggressive stock removal, blending, or finishing on irregular and curved surfaces.

Flap Disc Diameters and Grit Size

Flap discs are available in a variety of sizes (Dia. 4, 4-½, 5 & 7”). They are available in grits from 36 to 120. Low grit numbers reference coarser grits, while higher grit numbers reference finer grits.

Use our list below to determine which grit size you need:

  • For chamfering and edge beveling, use a coarser grit size between 36-60
  • For weld grinding and blending, use a coarser grit size between 40-60
  • For deburring and deflashing, we recommend a grit size of 60
  • For rust removal and blending, use a finer grit size of 60-80
  • For cleaning and finishing, use a finer grit size of 80-120

Backing Plates: Trimmable vs Traditional Fiberglass

Flap disc backing plates have traditionally been constructed of fiberglass. However, with recent design improvements, flap disc backing plates are now available in plastic or nylon and are trimmable. The trimmable version allows the operator to trim the backing plate to allow fresh abrasives to extend beyond the plate, allowing more utilization of the disc.

Trimmable backing plates are available with standard and high density flaps and can increase the disc life while ensuring the proper grinding angle is maintained during operation.

At Preferred Abrasives, we offer trimmable backing plates with a ⅝”-11 thread already built in at no extra charge to you.

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