What "high density" actually means
High density is not simply about packing more abrasive into the disc. What matters is how it is packed. In a conventional flap disc, each flap sits at a fixed pitch from the next. In an HD tool, the flap count per revolution is far higher and — critically — each flap is radially slit following a defined pattern. That slitting changes everything: the abrasive block keeps the density of a solid disc, with many cutting tips attacking the part at once, while each slit segment still bends independently.
In practice that means more simultaneous cutting points and faster stock removal; wear spread across many flaps, so longer tool life and lower cost per part; local flexibility, so the abrasive reaches inside holes, slots and internal contours and rounds the edge instead of grinding the face; and a rounding radius that stays consistent throughout the life of the tool. If you want the background on how brush deburring compares with other methods, we covered it in our guide to abrasive brush deburring.
This is the same principle behind the high-density tools that have become the market reference — such as the HERO range from Boeck — described as combining the highest abrasive density with extreme flexibility through a new arrangement and slitting pattern of the grinding flaps. That is the family our HD competes in, made in Barcelona and priced accordingly.
HD: the baseline
Our HD range applies this principle with a high flap count and radial slitting. It is built for the bulk of the work: deburring and edge rounding on laser-cut sheet, slag and cut-oxide removal, and a uniform surface finish in a single pass. It is at its best on flat parts and open geometries, where feed rate and finish consistency are what count.
HD PRO: same density, twice the travel
HD PRO is the evolution, and the change is subtler than it first looks. It carries exactly the same number of flaps as HD — there is no less abrasive. What changes is how they are grouped: instead of sitting one by one at single spacing, they are arranged in pairs, with double the gap between pairs.
More flexibility. A pack of two flaps with twice the clearance ahead of it has far more room to bend. The abrasive block deforms more and adapts to geometries that resist a standard high-density disc: closed contours, tight radii, embossed parts, hole interiors.
More aggressiveness. The open gap between pairs lets each pack strike the part with impact rather than rubbing continuously. The cutting action is livelier, and swarf and dust clear far better.
Lower thermal load. More spacing means more airflow. On heat-sensitive materials — stainless, aluminium — that means less risk of discolouration and of the abrasive loading up.
Same abrasive reserve. Since the flap count does not drop, the tool starts with the same amount of abrasive; only the way it is delivered changes.
Which one should you use?
Quick rule: flat parts and consistency of finish → HD. Holes, internal contours, or a larger rounding radius in fewer passes → HD PRO. On many lines the two work best together: HD PRO on the first station to strip slag and do the bulk of the rounding, HD on the second to even out the finish.
Formats and machines
Both ranges are manufactured for the standard mountings in the sector: discs for Costa, Timesavers and equivalent deburring machines; discs with 12 mm shank for robot and articulated-arm cells; M14 thread for hand-held angle grinders; hand blocks for touch-ups and off-line parts; and rollers in various widths for continuous lines. Grit is selected by application, from coarse for heavy laser slag through to fine finishing.
The 125 mm grit 60 HD disc with Costa mounting is available now — see it in the shop. Other diameters, grits and mountings are made to order.
Have a part that is giving you trouble — a hole that will not round properly, a finish that will not come out even, tool consumption that is too high? Send it to us and we will propose the configuration. We run samples.
CEPICAT — industrial brushes made in Barcelona since 1964.