Rieter

Degree of cleaning and resistance to cleaning

Index

Whereas formerly the cleaning effect of a machine could only be estimated, today it can be established fairly exactly, reproducibly and so as to enable comparisons to be made. For this purpose, the cleaning index C is defined as:

C_T = \frac {D_F -D_D}{D_F} \times 100 \%

where DF = the dirt content of the feed material; DD = the dirt content of the delivered material; and T = total. The dirt content is usually determined with the aid of gravimetrical methods such as MDTA3, AFIS or Shirley Analyser. Fig. 30 from Trützschler  [16] illustrates the cleaning indices of individual machines and the complete blowroom/card installation.

The cleaning index is heavily, but not solely, dependent on the dirt content. The particle size and adhesion of the dirt to the fibers, among other things, also have an influence. Hence, the cleaning index may be different for different cotton types with the same dirt content. There are types that can be cleaned easily and others that can be cleaned only with difficulty.

A new concept has been introduced to represent this ease of cleaning, namely‚ “cleaning resistance”. Fig. 31  References[16] shows the conditions in a horizontal cleaner:

  • zone I represents a cotton with low cleaning resistance;
  • zone II a cotton with medium resistance; and
  • zone III a cotton with high cleaning resistance.

Fig. 30 – Increasing degree of cleaning from machine to machine; A, degree of cleaning of blowroom machines; C, degree of cleaning (on the vertical axis); V, feed material; M1 – M3, blowroom machines 1-3; C, card

Fig. 31 – Resistance to cleaning (cleaning compliance) of various types of cotton; A, degree of cleaning of the machine; B, initial dirt content of the cotton; I, zone of low resistance to cleaning; II, zone of medium resistance to cleaning; III, zone of high resistance to cleaning.