Crimp Rigitidy Test

The ability of stretch and bulk yarns to collapse longitudinally is importance because the degree of crimp rigidity influence the properties of the fabrics product from this yarns.Crimp rigidity is a measure of the ability of a textured yarn to recover from stretch,and is related to the bulking potential of the yarn.In the tester developed by the Hosiery and Allied Trades Research Association, a load equivalent to 0.1g per denier is suspended from a skein of yarn which is then impressed in water at room temperature.After two min its Length, 'L' is measured.The load is then reduced to 0.002g per denier and after a further 2 min the reduced length,L2,is measured.The crimp rigidity is give by formula:

The apparatus for the test,supplied by Shirly Development Ltd is shown .The gate tensioner is adjusted so that the crimp in the yarn is just removed when the skein is being wound.A range of weight is required to accommodated the various denier encountered.Thus if the nominal denier were 20 then a skein of 50 strands would be wound and the heavy weight used would 100 g to give the required 0,1g per denier initial loading.The appropriate light weight would be 2g.For a 200 strand skein is used, the heavy weight 400g and the light weight 8g.A table gives the recommended skein strands and weight value.

The time taken to carry out a test is about five min.For firms who need to carry out large numbers of test .