Blowroom & Carding
Cleaning efficiency can always be raised. Selectivity is what says whether it should be.
— strikes/kg
Blade passes per kilogram of fibre through the point
Strikes per kilogram counts blade passes past the feed, not impacts on an individual fibre; a tuft may be struck several times or pass between blades, so the figure is a treatment intensity to compare between settings rather than a literal impact count. Tip speed is the peripheral speed of the blade and takes no account of the relative velocity of the fibre, which is already moving - the true impact velocity is lower, and by more at high feed speeds. Specific energy is total drive power over throughput and includes windage and bearing losses, which on a lightly loaded beater can be most of it, so compare it between similar machines rather than across types. The trash and lint split of the waste needs a Shirley Analyser or equivalent separation; estimating the good-fibre fraction by eye is where this calculation most often goes wrong.
Opening Intensity, Beater Tip Speed & Cleaning Selectivity — free, with the formula and a worked example, at Textile School.