Flap Discs

Flap Discs 

At Engweld, we stock a wide range of flap discs from leading brands such as Klingspor, 3M, and Abracs, as well as our own range of Engweld discs. They are manufactured to the highest EU specifications and come with the OSA seal of approval. These flap discs efficiently remove stock, grind, blend, and provide a smooth finish.

Available in a range of sizes and grit types, you’ll be sure to find the ideal flap discs for your project with us.

What are flap discs used for?

Flap discs are remarkably adaptable abrasive tools, offered in a wide variety of abrasive materials and grit dimensions to meet diverse customer needs. They are the perfect selection for various stages and procedures in metal fabrication, ranging from stock removal to rectifying surface flaws and deburring.

See our complete guide for flap discs that explains everything you need to know about flap discs and how they compare to other abrasives such as grinding discs, fibre discs, and flap wheels. 

KLINGSPOR SMT Flap Discs offer an aggressive cut while leaving a pleasing finish. Often, one of the SMT discs will take the place of what is now two separate grinding operations - heavy weld removal with a hard grinding disc and then final blending and clean-up with a fibre disc. A built-in fibre-reinforced consumable backing plate eliminates the need for a separate backing pad. Plus you may use your standard angle grinder mounting nut.

Engweld Silver Flap discs are made of alumina-zirconia coated flaps, fastened equally to glass-fibre reinforced resin backing plates or glass fabric backing plates. For most metal grinding applications including the working of welding seams, deburring, de-rusting, and cleaning of castings. They are available in sizes from 4-1/2" and Grits: 40, 60, 80.

Klingspor SMT 624 a new twist on convex flap discs. The new SMT 624 utilises a 12° angled backing plate. This will enable the disc to be used on more severely curved surfaces like pipes and storage tanks. Available in sizes 4- 1/2", 7" and Grits: 36, 40, 50, 60, 80, 120

Considering grit types: 

In the same way that sandpaper grains come in an array of sizes, with each grit size used for a certain application, flap disc grains work in the same way. At Engweld, our grit sizes range from 36 to 120, the larger the number, the finer the grain, and the smaller the number, the coarser the grain. 

Flap discs with coarse grains are generally used for the initial shaping and removal of stock, while finer grains are used for finishing and refinements.

Here is a quick breakdown of what the grit numbers actually mean:

1. 36 - 40 Grit: Heavy-duty grit for heavy-duty applications such as removing large amounts of stock from workpieces. 
2. 36 - 60 Grit: Great for edge work, including edge bevelling and chamfering.
3. 40 - 60 Grit: Well suited for applications such as weld blending and grinding.
4. 60 Grit: The perfect size for deflashing and deburring.
5. 60 - 80 Grit: The best choice for finer work such as blending and the removal of rust.
6. 80 - 120 Grit: These fine grit discs are ideal for finishing, cleaning and refining. 

When to choose coarse-grain flap discs:

Coarse-grain flap discs are ideal for quick stock removal and situations where a highly polished final surface is not a priority or when the client is indifferent about the finish and simply wants the task completed swiftly. The coarser the grain, the faster the rate of material removal (subject to the material type), but it may leave deep scratches that could be challenging to smooth out later.

This is especially noticeable when comparing finishing procedures on carbon steel and stainless steel. The inclination might be to always choose coarser grains, but this could complicate and extend your finishing alternatives in the future.

Coarse grains are also the preferred option for softer materials like soft steel and aluminium.

When to choose fine-grained flap discs:

Fine-grained flap discs are ideal when a project requires a smooth and polished finish. They are typically employed in the final stages of the grinding process to eliminate deeper scratches left by the rough grain during stock removal.

For example, stainless steel often necessitates extra surface finishing procedures because of the characteristics each process bestows on the material.

A highly polished finish is mainly used for aesthetic reasons, such as the number 4 finish, which is selected for its anti-fingerprint and anti-bacterial properties in commercial handrails and similar applications.

After the initial stock removal using a coarser-grained flap disc or grinding wheel, the scratch would appear unattractive on a stainless steel surface.

Moreover, finer grains are more efficient on smaller contact areas and are better suited for harder and more brittle materials.

FAQs

How to use a flap disc?

You can use a flap disc in the same way that you would use grinding wheels, with the main upside being that they have a much softer feel than grinding wheels do. And while the grind is much like hard grinding wheels, giving the operator greater control, and reducing the risk of removing too much stock or gouging the workpiece.

They are an ideal choice for a wide range of applications, as they allow the operator to save time, and cut costs, by performing both grinding and finishing in one efficient process.

Flap discs are commonly used on angle grinders, so you may also want to read our guide for angle grinders.

What grit flap disc for mower blades?

One of the most common uses for flap discs is for sharpening the blades on lawnmowers, and having the ability to do this yourself is a great way to reduce your mower servicing costs! 

Grit size of between 60 and 80 is generally considered to be the sweet spot for sharpening lawn mower blades, aggressive enough to sharpen when needed, but also affording the operator enough control to ensure that not too much stock is removed.

Safety First

As you would when you are using any type of power tools, when you are using flap discs you should always operate with your safety in mind.

• Always inspect the disc before using it, if there are any signs of damage do not use it. Adopt the “better safe than sorry” attitude.
• When using any coated abrasive products, you should always use the guard on your grinder.
• You should always prevent and remove any build-up of the material you are working with from your flap disc. This is called preventing “load up.”
• Please review all relevant safety materials and, if possible, receive training to use them.
• Never wear loose-fitting clothing or hanging jewelry, for obvious reasons!

To discuss your abrasive requirements, please contact Engweld using our contact form.