Evaluation of the pinpoint effect on carpet appearance.

In this article, a novel method for evaluating the pinpoint effect of pile yarns of carpet is introduced. The method was initially accomplished by presenting a standard method for bundle preparation. Afterward the changes in free spaces between yarns in bundle cross section introduced as an index for evaluation of the degree of pinpoint effect of heat-set yarns on carpet appearance. To achieve the objectives of this research, yarns of different twist were heat set at various times and temperatures. The ratio of free space between yarns to the total area of the bundle was obtained using image processing technique and defined as the index of pinpoint effect. Taguchi method of experiments design was applied to investigate the effect of the mentioned controllable factors of heat-setting process on pinpoint effect of pile yarns of carpet. The results established that increasing the twist, time, and temperature positively contributes on pinpoint effect. Higher twists, times, and temperatures create a jam structure resulting in higher packing density of the yarn and better pinpoint effect. The results of objective method are in good agreement with those of subjective method. Consequently, the objective method of calculating the pinpoint effect can be used as a reliable method to evaluate the pinpoint effect of pile yarns on carpet appearance. [ABSTRACT FROM PUBLISHER]