Resin Fibre Discs are flat discs used for heavy grinding and weld removal.  They are used for similar applications as Flap Discs. Resin Fibre Discs consist of a stiff fiberboard backing coated with a single layer of resin and abrasive. Arc’s Resin Fibre Discs have grinding aids in both the AO and ZA products. This grinding aid helps performance and keeps the disc cooler during grinding. The discs have an arbor hole to allow them to be attached to a back-up pad which they are always used with.

Uses and Advantages

RFD’s are used for heavy stock removal on electric and pneumatic angle grinders. As they are 2-dimensional and only have a single layer of grit they have a limited life span. Once the grit has lost its sharp edge the disc can be discarded. Unlike flap discs no new abrasive is exposed as the surface wears down.

Heat Build Up and Prevention

During grinding excessive heat is a problem for two reasons:

• Local heating can blacken the metal surface and damage the surface structure
• Excessive heat shortens the life of the abrasive.

Excessive heat can be overcome via

• Selecting the correct disc for the job (see our applications section)
• Choose a disc with a self sharpening grain such as zirconia or ceramic. If the grain is self sharpening it will give a cleaner cooler cut.
• Choose a disc with a grinding aid. Grinding aids are built into the resin component of the disc and reduce friction and heat build up during use

Correct Use of the Disc

Do not apply too much pressure or dwell on one area for too long. Use a sweeping action to grind a larger surface so that the work is not concentrated in one area.

Use a Spiralcool back up that increases airflow around between the disc and the backup pad which takes heat away from the work area.

Size and Shape

The three most common sizes are 4½”, 5” and 7”. Also available are 4” and 91/8” but these are much less common. The arbor hole is usually 7/8” (only the 4” discs have 5/8” arbor holes). Additional to the arbor hole, discs sometimes have slots radiating out from the center to allow the disc to conform better to the locking nut/washer assembly of the back up pad. Another common feature is a contoured profile which can help keep the disc flat during storage.