A Fickert block is a rectangular metal bond abrasive, 56 mm thick and 133 mm long, that runs in a set of six on a polishing line. Most buyers ask which grit to buy. The better question is what each grit removes.
The sequence is a scratch-removal chain
Every grit leaves a scratch pattern. The next grit exists to remove that pattern, not to make the surface shinier. 36# takes out the calibrating marks. 60# removes the 36# pattern. 120#, 220#, 400# and 800# follow the same logic. Gloss appears at the end because the last scratch is fine enough to reflect light, not because any single block polished anything.
Skipping a step costs more than the block
The temptation is to drop a head to raise line speed. What happens instead is that one grit has to remove two generations of scratch depth, cannot, and the line runs longer to compensate. The block you saved costs more in spindle hours and power than the block cost.
Where lines actually lose gloss
- Coolant volume. Too little water and the swarf stays between block and surface and re-scratches it.
- Blocks left in the line after they have gone out of flat. A worn block cuts only on its high corner.
- Head pressure set by habit rather than by material. Sintered slab and marble do not want the same load.
What we need to specify a set
Number of polishing heads on your line, the material, the target gloss in GU if you measure it, and the grit sequence you run now. Six blocks per set, MOQ 6 pcs, model D126.