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Home / en-de > Press > News > Grind like the professionals - Part 3

Grind like the professionals - Part 3

Every fibre disc requires a suitable backing pad. It ensures stability, optimum distribution of force, and safety when working. If the pad is worn, the performance of the grinding discs suffers – and it’s high time they were replaced.

Part 3 - The backup

Every fibre disc requires a suitable backing pad. It ensures stability, optimum distribution of force, and safety when working. If the pad is worn, the performance of the grinding discs suffers – and it’s high time they were replaced.

 

Fibre discs, or more accurately, vulcanised fibre grinding discs, are the medium of choice when high removal and yet a beautiful finish are required. They are softer and more flexible than conventional grinding discs and are predominantly used in metal processing applications. Like the FS 964 and FS 966 premium fibre discs with ceramic grains from Klingspor. They are clamped onto the angle grinder together with a backing pad. This is prescribed by DIN EN 13743 and is also sensible because grinding would not function at all without it.

The flexible fibre disc requires counter-pressure to prevent it from moving or tearing. The user is only able to build up the required pressure on the material to be processed by using a backing pad,” explains Wolfgang Kaiser, head of Test Field and Service at Klingspor. The backing pads are manufactured from a thermoplastic. When making the choice, the application is crucial: smoothing out a weld seam requires a coarse fibre disc with a grit size of 50, and a suitably hard backing pad. On the other hand, the fine sanding of surfaces or contours and preparing them for the application of paint requires the use of fibre discs with a finer grain combined with a soft, flexible backing pad. A worn backing pad is the reason why the performance of the fibre disc drops by up to a third.

hard backing pad will warp as a result of the frequent changes in temperature, the disc no longer lying flat and the pressure build-up no longer as desired. A softer backing pad will lose its elasticity. This is why it is important to change them regularly. There is no simple answer regarding when the time is right. “There are applications whereby the backing pad is worn after only 50 discs, and there are applications when it’s time to change after 500 discs. This is why visual inspections are the be all and end all,” emphasises Kaiser. Taking a close look at the fibre disc helps identify wear early on (see the series of photos below). Then it’s time.p>

Pro tips

“Using old, warped backing pads reduces performance by up to 30 per cent,”

advises Wolfgang Kaiser, Test Field Manager..

 

 

1. In good shape: The fibre disc together with a new backing pad grinds nice and evenly.

                 

2. Sign of ageing: When the fibre disc “burns” in some places while other places look new, performance drops.

3. The right choice: For removing weld seams, a coarse fibre disc with a grit size of 50 and suitably hard backing pad are ideal. For the fine sanding of surfaces or contours, fibre discs with a finer grit size combined with a soft, flexible backing pad are suitable.

 

4. With feeling: Apply the fibre disc flat to the surface and ensure that the edge of the grinding equipment does not cut into the workpiece. Otherwise both the disc and the backing pad will suffer.