Holding Length: Effect on Digital Fibrograph Span Length

Abstract

Fibers scanned for length by most instruments must be held in position for the scan. The holding length has been determined mathematically as being of the order of 4.06 mm ( 0.16 in.). Since the start of scan begins at 3.81 mm (0.15 in.) from the holding edge, the average start of scan actually begins at a length of 7.87 mm (0.31 in.). A general holding length is shown with a photomicrograph. Applying this concept to data presented in the literature gives acceptable results in all but one case. The holding length appears to be a function of fiber rigidity, which means that it varies.

Characterizing the total within-sample variation in cotton fiber length using the High Volume Instrument fibrogram

“…The portion of the fiber beard going from the edge of the comb to the scanning starting point is 3.81 mm (0.15 inch) long and is the same for all Uster HVIs. [21][22][23] Values are expressed as distances and not lengths because the starting offset distance is not included for analysis in this research. However, this is a constant offset and including it should not change the presented results.…”

“…Before measurement, the beard is brushed to remove loose fibers and trash particles. The beard is then scanned over a light source starting 3.81 mm away from the base of the comb to the end of the fiber sample, 21,22 and a receiver on the opposing side of the beard is used to measure the amount of light attenuated by the beard. The starting point of the scanning of the beard is the maximum point of light attenuation and is used to standardize the measurement to 100%.…”

“…Because many fibers are not measured by the HVI length module, that is, they are either trapped in the comb needles or they do not extend into the portion of the beard used to measure length, these two length parameters represent only the longer fibers in the sample. [21][22][23] After extracting these two length measurements, the fibrogram data are discarded by the instrument. HVI fiber quality parameters, including fiber length measurements, are often used as indicators of potential yarn quality.…”

Development of a new hybrid yarn construction from recycled carbon fibres for high-performance composites: Part IV: Measurement of recycled carbon fibre length

“…In the case of cotton fibres, a clamp holding length of 4.06 mm was reported by Krowicki and Thibodeaux. 32 In addition, for crimped fibres such as cotton or wool, the crimp cannot be eliminated within the fibrograph method, thus additionally shortening the tested fibre length. Hertel added a correction factor of 1.19 to the measured length values of cotton fibres for the calibration of the fibrograph system in Hertel.…”

Investigation of a Multivariate Correction Method for HVI Fibrogram Measurements

“…After removing extraneous matter and loose fibers through brushing (Figure 1C), the fiber beard is scanned over a red-light beam (Figure 1D) while a sensor positioned above the beard measures the amount of light attenuated by the beard [17][18][19][20]. The starting point of the scan is 3.81 mm (0.15 inches) from the edge of the comb [21,22] and determines the total population of fibers to be scanned. The amount of light is maximally attenuated at the starting point, the base of the beard, so the measurement at the start of the scan is normalized to 100%.…”