Flap Discs for Angle Grinders and Die Grinders
Whether you're grinding welds, deburring sharp edges, or polishing metal to a mirror finish, having the right flap disc is crucial. At Empire Abrasives, we carry a wide selection of the best flap discs designed for maximum performance, longevity, and superior results. From aggressive material removal to fine surface conditioning, this guide will help you select the perfect grinder flap disc for your grinder and your specific project.
Flap Disc Buyer’s Guide - Step 1 — Determine Abrasive Grain by Material & Task
| Application / Material | Disc Setup (Grain/Coating) |
|---|---|
| Grinding or Blending Stainless Steel | Ceramic (coolest cut prevents discoloration + has the longest life), Zirconia (value workhorse) |
| Grinding or Blending Hard + Exotic Aerospace Alloys (Titanium, Nickel, Cobalt Alloys) | Ceramic (aggressive grinding on tough metals + best for heat sensitive metals) |
| Grinding or Blending Hard Metals (carbon/mild steel, cast iron, etc.) | Zirconia (durable grain for heavy stock removal and extended use) |
| Grinding or Blending Aluminum & Soft Non-Ferrous Metals (aluminum, brass, copper, bronze) | Ceramic grain + calcium-stearate (cooler cutting with anti-loading /clogging coat) |
| Finish & Prep (minimal base-metal removal) | Surface-Conditioning Flap Discs (controlled finish; great after weld cleanup) |
| Detail Work & Tight Spaces | 2” & 3” Mini Flap Discs (quick-change Roloc™ style) |
| Final Polish | Felt polishing flap disc + polishing compound |
Flap Disc Buyer’s Guide - Step 2 — Determine the Best Flap Disc Setup (Shape / Density)
Shape/Type:
- T27 (flat): Best for blending, flat surfaces, finishing
- T29 (conical): Best for aggressive grinding, contours/edges
- Curved Edge: Best for grinding fillet welds and in tight corners
Density:
- Standard: Everyday grinding and blending for quick material removal
- XL High Density: (≈50% more flaps) for longer life and smoother grinding
Flap Disc Buyer’s Guide - Step 3 — Pick the Right Grit(s) - Flap Disc Grit Chart
| Your Task | Best Grit | What It Does |
|---|---|---|
| Heavy weld removal, beveling, fast rust/paint removal on durable steel | 36 / 40 (coarse) | Maximum stock removal and fastest cut; expect a rough finish—plan to step down to 60–80 to blend. |
| Weld grinding & initial blending | 40 (36 for very heavy welds) | Rapid removal with a workable finish; good first step before 60. |
| General metalworking: blending, deburring, shaping | 60–80 grit | Balanced removal and surface quality; removes 40-grit scratches. |
| Thin-gauge or softer metals, edge cleanup, surface prep | 80 | Clean finish with minimal scratching/gouging; great before primer. |
| Final finishing & coating prep | 120 | Smooth finish ready for paint/powder; removes 80-grit marks. |
Additional Considerations
- Disc size & RPM: match grinder (2–3", 4-1/2", 5", 7"); never exceed disc’s max RPM
- Hubbed vs standard arbor: hubbed 5/8-11 = faster change-outs.
- Stainless Steel: look for “contaminant-free” options.
- Coatings: grinding aid for stainless/hard alloys; anti-loading (stearate) for aluminum.
Flap Disc FAQ
Q: What is a flap disc?
A flap disc (aka flapper disc) is an abrasive tool made up of multiple layers of overlapping abrasive “flaps” (like strips of sandpaper) adhered to a central hub in a wheel shape. As the disc is used to grind metal or other surfaces, the top layer of abrasive wears away in a controlled manner. Once the material on the outer layer is used up, that sheet will tear off to expose a fresh layer of abrasives.
Q: What are flap discs used for?
Flap discs are most often used for grinding and deburring metal surfaces, removing paint and rust, stock removal, and smoothing out imperfections. Specialty flap discs can be used for polishing and/or surface conditioning metals as well. Below is a list of uses of flap discs:
| Grinding | Blending | Finishing | Deburring | Deflashing |
| Edge Chamfering | Stock Removal | Paint & Adhesive Prep | Shaping Metal and Hard Woods | Cleaning Metal |
| Weld Prep | Cleaning Weld Lines & Spatter | Blending Welds | Fillet Weld Sanding (curved flap discs) | Sharpening Tools and Blades |
| Surface Conditioning (non-woven flap discs) | Polishing (felt flap discs) | Surface Smoothing | Paint & Rust Removal | Varnish or Epoxy Removal |
Q: What's the difference between Type 27 and Type 29 flap discs?
The “type” of design for flap discs specifies the angle that the abrasive sheets are aligned into the wheel.
- T27 (Flat Discs) - Type 27 flap disks are flat. This makes them better for smoothing/blending surfaces as well as flat sanding. Use them at a 0-15° angle.
- T29 (Conical Discs) - Type 29 flap discs have their abrasive sheets slightly angled on the face of the disc. This allows for more aggressive grinding and is better for contouring and shaping surfaces. Use them at a 15-25° angle.
Q: What abrasive material should I choose? (Ceramic vs. Zirconia vs. Surface Conditioning)
There are a variety of different abrasive grain types that can be used for flap discs and each has their own purpose.
- Zirconia flap discs are tough, self-sharpening, and great for grinding metals like stainless steel, carbon steel, and most other hard metals.
- Ceramic flap discs are made with a premium, high-performance grain. They last the longest and cut the fastest, especially on high-alloy steel and titanium. They also grind cooler, reducing heat discoloration on the metal.
- Surface conditioning flap discs (non-woven) are best for blending, finishing, cleaning, and oxide removal with a cool, low-pressure cut. They are great on stainless and aluminum, leave a consistent satin finish, and won’t change part dimensions.
Q: Can I use flap discs on aluminum or soft metals?
Yes, but make sure you choose the right one. Soft metals like aluminum and copper are highly sensitive to heat and easily cause abrasive discs to clog. Our flap discs for aluminum are specially designed with premium ceramic grains and an anti-loading calcium stearate coating that lets you grind soft metals without damaging them.
Q: What’s an XL/High Density flap disc?
High density flap discs have about 50% more flaps per disc for longer life, smoother feel, and better contact on curves/irregular surfaces. They are made for individuals who do a lot of grinding and want an abrasive that will last even longer.
Q: Can flap discs be used on wood?
Yes, they can be used on hard woods to shape, smooth, and remove material, BUT go light and use finer grits (60–120) to avoid gouging. Flap discs are aggressive and can easily “eat” wood and are prone to clogging and heat damage, especially with soft woods. For finish sanding, a sanding disc is usually better.
Order Today
Now that you know how to choose the perfect flap disc for your project, it's time to find the right one. Explore our full collection of high-quality flap discs and get the job done right. Still need some guidance? Contact our abrasives experts who can help answer any questions.