Increase of the Screening Efficiency by Enlarging Oblong Holes

On the basis of former studies, the method of screening with enlarged oblong holes was presented to improve screening performance in cleaning and grading farm products or their seeds. The results of analysis and experiments showed that the method is practicable on the condition that the required precision of screening is not extremely high. The effective coefficient of screening was used as a new index to comprehensively appraise screening performance.