What is Fiber Length?

Fiber length refers to the distance between the two ends measured when the fiber is straightened without the influence of an external force. The fiber length unit of measurement is millimeter(mm).

Fiber length is the basis of determining spinning equipment and spinning process parameters, and it is also an important factor to determine yarn quality, so fiber length is an important index to measure fiber quality. Chemical fiber length can be controlled artificially, natural fiber length is formed naturally, so it is particularly important.

Fiber Length Index

Take cotton fiber as an example, the cotton fiber length is not uniform, generally speaking, the modal length, quartile length, evenness and short fiber content are used to express the length and distribution of cotton fiber. The modal length is the length of the fiber with the highest content in cotton fiber. Quartile length refers to the average length of the fiber that is longer than the modal length, which is used to determine the roller gauge in the spinning process. Short fiber content refers to the weight of the fiber as a percentage of the total fiber that which fiber length less than a certain length limit. Generally, when the short fiber content is more than 15%, the yarn strength and evenness will become significantly worse.

Test Principle

The fiber length is measured by optoelectronic technology. Firstly, grab about 120g from the loose samples randomly, Which is locked with a spiral comb clip and then straightened under a certain tension after treatment, at last, pass the fiber through an optoelectronic instrument. After irradiating the fiber with a certain signal light source, accept the change of the light intensity by the photoelectric receiver, which forms the distribution curve of the fiber length, and then calculates the various indexes of the fiber length.

The Method of Measure the Fiber Length

At present, there are three kinds of fiber length instruments: grouping weighing instruments, automatic instruments and photograph fiber length tester(optoelectronic instruments).

The greatest advantage of grouping weighing instruments is that the principle is clear, but the operation is complicated, the error source is complex and uncontrollable.

In principle, the automatic instrument can not test cotton fiber length in time. The tested sample should be stored in a certain humidity environment for a period of time, otherwise, it is easy to bring static electricity on the fiber when preparing the sample.

Photograph fiber length tester is widely used in many precision measuring instruments because of its high measuring speed, high sensitivity, and precision.

The photograph fiber length testing method has more indexes than the traditional testing method, the testing speed is fast, the result repeatability is good, can provide the upper half average length, the length uniformity ratio, the short fiber content index and other indicators, easy to operate.