Design And Fabrication Of Yarn Shrinkage Checking Machine

American Society Testing for Materials is an international standards organization. This standard must be followed by the entire manufacturer who manufactures the nylon and yarns. This testing shows the actual shrinkage level of yarn under some thermal conditions. During the ASTM D4974 testing procedure, a hot air thermal shrinkage oven is used to subject the specimen of yarn or cord to dry heat for a specified period of time while under a specified tension. Shrinkage is the process in which the yarn becomes smaller than the original size. The percent shrinkage is read directly from a scale or display on the instrument while the specimen is still under tension and exposed to heat. The standard ASTM D4974 testing method is to heat the sample to 177 Degree Celsius for 4 minutes with a pretension load of 0.05 grams per denier. A lower pretension value of 0.01 gpd is also mentioned in the standard for yarns with lower shrinkage values in order to give a more accurate reading.