The Lea strength of yarn is one of the major properties on which the suitability of yarn for its ultimate end use depends. It is the standard method of measuring the strength of the yarn. The frictional forces rendered to the yarn in the lea test reduce the sensitivity of the test to detect weak places in the yarn. A weak yarn can also produce a low strength, but presence of an abnormally weak place in one of the treads may not be detected.
Instruments:
- Uster auto sorter 4
- Wrapping reel
- Weighing machine
- Lea strength tester
Specimen Preparation:
To determine the CLSP first we have to make a lea of 120 yards .we make it by using wrapping reel lea maker, it’s an electronic machine having a circular wheel with a diameter of 1.5 yards. To make 120 yards we fix the machine to 80 revolutions, a lea is formed when it complete 80 turns .This lea is then weighted on a weighing machine.
Machine Adjustment:
The machine adjustment includes the setting of lea strength tester that it should be on 0 moreover the Auto sorter should also be checked before measuring the count.
Procedure:
- First we have to make a lea of 120 yards.
- After the preparation of the lea it is weighted on weighing scale, and the count of the yarn is calculated through a formula. Count of the yarn = (length in yds/840)*(453.6/wt of yarn)
- The other way to calculate the count is through the auto sorter in which are all the weighted samples are placed separately and the count of the yarn is obtained automatically.
- To determine the strength of the yarn lea strength tester is used, it’s a vertical machine having two jaws one is fixated and the other is movable, there is a meter as well which give us the amount of force applied to the lea.
- This meter has two pointers both move simultaneously and when any yarn break’s the one point return to zero and the other remains at that breaking point giving the reading of yarn strength.
- We fix our lea in both the jaws and start the machine, movable jaws applied the force on the lea and breaks it of .The value is taken down and is multiplied by the count on order to get CLSP.
Features of Lea strength tester
Tensile Testing Machine consists of lower stationary base plate, a fixed cross tie on two supporting columns and a movable crosshead using a lead screw and nut mechanism. The Tensile Testing Machine has been designed in such way that one testing space is suitable for extra-long test sample, having long elongation.
- The facility of controlling the test via Microcontroller with Max-force, Tenacity & elongation.
- Data safety facility is also available.
- Max hold test can be carried very effectively.
- Extremely powerful internal software makes the machine versatile.
Technical Specification:
- For Checking Tensile Strength of Fabric / Yarn Lea
- Digital Tensile Testing Machine – 500Kgf with S Type Load Cell
- Least Count - 0.1Kgf
- Traverse Speed - 300 & 100mm /min.
- Max. Grip Separation –1000mm
- Min. Grip Separation – 100mm
- Power - 220V AC 50Hz.
- Drive – 1H.P. Geared Motor
- Safety Device – With Limit Switch to protect from Over Traverse
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