Fleece Sampling Terminology

Micron (µ) or Micrometre (µm)	One µm equals one-millionth of a metre (m), or one-thousandth of a millimetre (mm). A human hair is approximately 75-100µm in width. NOTE: micron and micrometre are the same unit. “Micron” is the old name, and has been superseded by the name “micrometre”, as defined by the International System of Units (Système International (SI) d'Unités)
Mean Micron	The average µm of a sample. The sum of individual fibre widths (in µm) divided by the total number of fibres. For example, 5 fibres of width 18µm, 19µm, 20µm, 20µm and 21µm have an average, or mean diameter of [18µm+19µm+20µm+20µm+21µm]/5 = 19.6µm
MFD Micron	Actual Mean Fibre Diameter - made up of along and between fibre measurements
MFD Var	The variation of Mean Fibre Diameter from the overall average of all samples tested
SD	Standard Deviation is a measure in µm either side of the MFD in which 68% of fibres lie and is +/-. For example, a fleece of average 20µm with a SD of 5 is written 20±5µm and means 68% of fibres lie within the range 15µm-25µm
CV_D%	Coefficient of Variation of Diameter. Also known as Covariance or CV. Expressed as a percentage of Standard Deviation and Mean Fibre Diameter. CV = SD/MDF×100/1
CF	Comfort Factor. An indication of how many fibres are less than 30µm. 0% of fibres above 30µm = 100% CF 3% of fibres above 30µm = 97% CF
%>30	The percentage of fibres greater than 30µm. The opposite of Comfort Factor
SF	A decisive figure for Processors. Spinning Fineness is a calculation of MFD and CV into a single measure of fineness expressed in µm. NOTE: a CV of 24% has a zero effect on Spinning Fineness. [ More... ] SF = 0.881MFD√[1+5(CV/100)²]
Curve	is the Mean Fibre Curvature measured in degrees per millimetre (deg/mm) of fibre length. The LOWER the angle, the LOWER the Staple Crimp Frequency
Curve SD	Measurement of the spread of Curvature. The higher the Standard Deviation (SD) the greater the distribution of curvature. - The lower the SD the more uniform the fibres are - Research is on-going
FEM©	Fine Edge Micron© is the number of µm LOWER than the MEAN where the finest 5% of fibres BEGIN
CEM	Coarse Edge Micron is the number of µm GREATER than the MEAN where the broadest 5% of fibres BEGIN

NOTE: Generally, the lower each of the SD, CV_D, SF, CURVE[SD], FEM and CEM values are, the better the fleece within each micron category.

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