Friction is very important to control during melt spinning processes. When yarns are spun at high speeds contact friction with every object in the process can cause so much heat that a yarn breaks. To prevent breakage a spin finish is applied as a lubricant to reduce friction. Too much of the spin finish or a too potent lubricant may cause slippage on godettes.
The friction between yarns is also important to measure when the yarn is used for weaving. It is undesirable that a woven fabric is easily thorn apart because the friction between yarns is too low. The optimal yarn-yarn friction can be determined and tweaked by using the right lubricant in the right amount.