The strength of a yarn and other properties of fabrics depend to an extent on the amount of twist given to it. Thus accurate determination of this factor is of prime importance is assessing the quality of any yarn. The amount of twist given to a yarn is usually determined by unwisting a known length of yarn and finding the number of rotations of one of its ends relative to the other which remove the twist completely. The equipment used for determination of twists of a yarn is known as twist tester.
The FEC Twist tester for yarns consists of a set of clamps, one of which is rotating and the other fixed .The rotating clamp is driven by hand through a speed increasing arrangement and a five digit re-settable revolution counter of twist the fixed clamp is pivoted on jewel bearing and carries of a pendulum arm having a sliding weight to give the desired tension to the yarn. The fixed clamp assembly can be moved over a guide bar for setting the required testing length of yarn which is which is indicated on a strip scale fixed to the base against a pointer attached to the moving assembly . A viewing plate and a magnifying glass are provided for accurate determination of the end point. A dissecting needle for ascertaining complete removal of twist is supplied as standard accessory with the equipment. The various components are fixed on a rigid cast iron base for strength and durability. The base is finished in off white synthetic stoving enamel paint and all parts bright chrome plated to give a corrosion resistant finish and highly aesthetic appearance. The motorized version of the tester is also available using a universal motor and a direction changing mechanism for selecting proper untwisting direction check.
Test length : 25 mm to 250 mm (25 mm to 500 mm for motorized version)
Load of test specimen : 0 to 100 gms
Counter : Five digit revolution counter to give S twist directly and Z twist by subtracting 10,000
Related Standard :
IS 832 – 1985 : Method of determination twist in yarn
BS 2085 – 1973 : Determination of twist yarn by direct counting method.
ASTM D 1423 : Determination of twist yarn by the direct counting Method