The swarf produced by the grinding process can get fixed in the grinding wheel. This so-called clogging or loading of the grinding wheel leads to a reduction of chip space, so that less cooling lubricant can get access to the machining location. On the other hand, swarf removal from the contact zone is also hampered. Process temperatures and machining forces rise because of increased friction, from which both workpiece and grinding wheel are more heavily stressed mechanically and thermally. Increasing grinding wheel stress from clogged pore spaces can lead to more wear due to breakaway of entire grains or grain groups.
We differentiate between three different clogging types: snarl chips, grit adhesions and layer chips.
While snarl chips only get clogged in front of chip-forming cutting edges in the chip space in an isolated fashion, grit adhesions coat individual grains or groups of grains. The extensive expansion of grit adhesions amount to only a few grain diameters. Layer chips are larger particles that can cover large areas of the grinding wheel surface [LAUE79].
Clogging characteristics are influenced by the material being machined, the design of the grinding wheel, cooling lubricant supply and the grinding parameters. For example, clogging has been seen to be especially frequent in the machining of ductile steel materials, aluminium or titanium alloys.
Several cleaning possibilities exist. Sharpening blocks can be used to remove clogging. A new dressing process also has a cleaning effect. A third possibility is the use of cleaning nozzles (see chapter 5).