Velcro sanding disc

The FERVI abrasive grinding discs here include fiberglass-backed, nylon-backed, fibre, Velcro and non-woven versions. The product group is divided into four main lines: SmartFlex, GrindFlex, Performance and Professional. The lines differ in grit range, diameter sizes and the materials they can grind. Diameters run from Ø75 mm for die grinders up to Ø180 mm for large angle grinders.

Grits start at P24 and P36 for weld removal and go up to P800 for finishing. Zirconium and ceramic grain versions are used on steel, cast iron and stainless steel. Backing pads, rubber holders, cartridge abrasive rolls and felt polishing discs are also included. This article explains how to select an abrasive grinding disc according to workpiece material, machine size and work stage.

All FERVI article numbers are imported and distributed as genuine goods at Titania.

Abrasive grinding discs in metalworking

Abrasive grinding discs serve weld removal, mill scale removal, levelling and surface finishing steps. The FERVI product group here includes fiberglass-backed flap discs, nylon-backed flap discs, Velcro discs, fibre discs, nylon discs and non-woven materials. Backing pads, rubber holders, hand blocks and felt polishing discs are also included. Users select according to workpiece material, machine size and the work stage required.

The grouping follows the manufacturer's four main lines: SmartFlex, GrindFlex, Performance and Professional. These four lines differ in grit range, diameter sizes and the materials they can grind. Besides those four lines there are two special-purpose groups collecting versions made for specific jobs. Once this division is clear, finding the right article number is much faster.

Fiberglass-backed flap discs

Fiberglass backing gives high rigidity, suitable when strong pressure has to be applied to a weld. The drawback is that the disc must be discarded once the flaps are worn through while the backing rim remains. The four fiberglass-backed lines run from entry level to the top level, differing in size and grit range. Buyers should first determine the diameter of the angle grinder in use.

DF21xx belongs to the SmartFlex line, in Ø115 and Ø125, used on steel and cast iron. The two versions in this line differ in the disc contact angle when holding the machine. DF4xxx adds the Ø180 size for large angle grinders and includes a Bigger version with more cloth flaps. All three GrindFlex versions use zirconium grain.

DF6xxx can grind stainless steel, not only steel and cast iron. This line also has the Tiger version with 70 percent more cloth for long grinding shifts. DF8xxx stands at the top of the four fiberglass-backed lines. Two features specific to this line are the P36 grit and the mini Ø75 size fitted to die grinders.

Nylon-backed flap discs

The nylon backing wears down together with the flaps, so grinding is possible right to the edge of the disc. This characteristic avoids the backing rubbing against the workpiece when the disc is nearly used up. The four nylon-backed lines repeat the division of the fiberglass-backed group. The differences lie in diameter sizes, grit range and each line's ability to grind stainless steel.

DN21xx comes in Ø115 and Ø125, including a double-layer version with twice the flap density. DN4xxx adds the Real Flat version with flaps arranged into a truly flat face. This version gives an even, fine grinding pattern and leaves no swirl marks. It is intended for grinding where the surface is left as is, with no further finishing step.

DN6xxx adds the Ø180 size and can grind stainless steel, two points the nylon-backed SmartFlex and GrindFlex do not have. The double-layer version in Ø180 suits long welds. DN8xxx offers P36 grit in all three sizes, intended for weld and mill scale removal.

Two special-purpose groups by material

The two special-purpose groups collect versions selected by workpiece material rather than by line. Ceramic grain cuts cooler than zirconium, so it is less likely to burn or discolour a stainless steel surface. Zirconium grain is cheaper and suits rough removal work. There is also a flexible curved disc that follows uneven surfaces, used on pipes and hard-to-reach corners.

DF9xxx includes a ceramic grain version for stainless steel and alloy steel, together with an Abranet grain version. DN9xxx has three versions all aimed at stainless steel. Among them, the flexible curved disc is dedicated to non-flat surfaces. When the workpiece is stainless steel, check these two groups before returning to the four main lines.

Velcro sanding discs and fibre discs

Velcro discs attach to a backing pad, change quickly and are selected by grit and number of dust extraction holes. The hole count must match the machine pad, because misaligned holes let dust clog the abrasive face and the disc wears quickly. For machines without dust extraction, use the hole-free version. The three factors to determine are diameter, hole pattern and grit range.

VDA115x comes only as a hole-free version with closed-coat grain, so it removes material quickly. VDA125x is made in one hole pattern only, 8 holes, matching the common 125 random orbital sander pad. VDA150x comes in hole-free, 6-hole and 8-hole versions, grit range P40 to P220.

The gold line VDG150x runs from P60 to P800, selected by grit and hole count. ZSA150x has zinc stearate against clogging but uses closed-coat grain, so it removes material faster. The three zirconium article numbers are VDZ115x, VDZ125x and VDZ150x, grit range P40 to P120.

Vulcanised fibre backing is stiffer than paper or cloth, so the disc does not buckle under strong pressure. FDCx uses ceramic grain that self-fractures into new cutting edges, staying sharp longer and cutting cool. DFVx attaches by Velcro to a backing pad for quick changes, available in Ø115 and Ø180. The P24 version is intended for cutting straight into welds.

Nylon, non-woven and polishing discs

The nylon and non-woven group serves the cleaning and finishing steps after rough grinding. The abrasive grain sits inside an open fibre web, so it lifts off dirt while barely cutting into the metal. Typical jobs are removing old scratches, derusting and creating an even surface. Only after this step does work move on to felt polishing.

CSDSx mounts on a drill through the centre hole, sizes Ø100 to Ø200 mm. CSCDx mounts on an angle grinder through the 22 mm hole, running at 11,000 rpm at Ø115. UNCDx has three Ø115 versions selected by grain type. SCDx includes both disc and roll forms.

VDFx is used for the final step, spreading polishing compound over the workpiece surface. Permitted speed ranges from 6,000 rpm at Ø75 down to 2,500 for the large size. DFC115-M14 has an M14 thread, 12 mm thickness and a maximum speed of 12,500 rpm. MDF075 in Ø75 mm is used with polishing powder or paste.

Backing pads, holders and hand tools

Velcro discs and abrasive rolls need the correct backing pad or holder to be mounted. Thread, shank, diameter and permitted speed must be cross-checked before mounting. The larger the pad, the lower the maximum rotational speed. This group also includes hand blocks for areas a machine cannot reach.

0459 is Ø150 mm with 6 dust extraction holes, a 5/16 inch shank and a maximum speed of 12,000 rpm. VSPx has an M14 thread; the Ø75 size runs up to 12,200 rpm while Ø180 is limited to 5,000. SGCx comes as a cylindrical body type for cartridge rolls and a flat-face type supporting Ø50 and Ø75 discs.

TDV is 150 mm for Velcro discs used by hand. TEV120 measures 70 x 120 mm, shaped to fit the hand, with quick paper changes. BSA100-060C is abrasive on four faces, P60 grit, for both dry and wet sanding. 0559-T has a 30 mm hole and does not include a belt.

The roll and abrasive head group includes RSAx in 115 mm width and 25 m length, CRDx in Ø6 to Ø12 mm and RGT with a 6 mm shank. Contact the technical team to cross-check machine size, grit and mounting type before ordering.