3M™ Shaft Mounted Flap Wheel 339 Introducing the 3M™ 339, this flap disc provides a versatile one disc system that features an impressive aluminium oxide abrasive. The 339 flap wheels are long-lasting and precision made to provide you with overall consistency and greater control over a number of critical tasks. They are excellent for cutting and polishing of metallic components and are a one-step system for grinding and blending. The 339 is a wheel with abrasiveis desinged to be mounted onto a spindle. Features and Benefits • Fast cutting aluminium oxide abrasive
• Flexible X-weight backing
• Spindle mounted
• Excellent cut and polish capabilities Applications Flap discs are a type of power tool accessory that can be used in conjunction with angle grinders to grind, blend and remove excess material, depending on what the task is that they are being used for. Flap discs are available in different grit sizes and each grit size will be more or less suitable for removing excess material from welds or removing rust, descaling, preparation of surfaces for painting or polishing and other surface finishing applications. They are most commonly used in:

• Building and construction industries
• Automotive engineering and manufacturing
• Ship and boat manufacturing
• Metal fabrication Are flap discs more effective than standard abrasive discs? While both discs can be used for wood and metal surfaces, flap discs are better suited for use with metal. Abrasive discs are better at removing material from a surface, but for grinding metal surfaces, flap disc presents a more durable and long-lasting solution. They even have some advantages over grinding wheels in that, while they may not remove metal as aggressively, they are slightly safer to use and produce less sparks. What is the difference between flap discs and flap wheels? Flat discs are designed to be used with hand-held equipment such as angle-grinders, to be moved over a surface or medium that needs to be sanded or polished. Flap wheels were originally designed to be used with a static machine such as a fixed buffing machine, where the medium is used against the belt. However, flap wheels can also be used on handheld rotary tools such as electric drills. A flap wheel strikes a surface in a less regular way that a flap disc, meaning there are less uniform scratches, which is desirable particularly for metal buffing and polishing. They also last longer than conventional discs as the flaps wear from the outside in, rather than consistently across a disc surface. Conventional flap discs, however, may present a more cost-effective solution for less specialized applications. How should these wheels be stored? Flap discs should be stored flat, avoiding damp and frost or wide temperature variations. What do the different grit sizes mean?

• P40 Grit – Useful when you need to remove heavy stock from a surface.
• P60 Grit – For when you need to remove stock from a surface, but will need to refine the finish.
• P80 Grit – This is for light stock removal and sharping only. Why choose 3M? 3M is a leading innovator of abrasive technologies, constantly evolving to provide ideal solutions to industrial and commercial applications. With 3M you can be assured of a wide selection of quality products.