Knitted yarns durability tester with vibration unit

A tester for measuring a durability of a knitted yarn portion in which at least two sets of yarns, including a set of first yarns and a set of second yarns, are intersected, said tester comprising:

• a first holding unit holding ends of said at least two sets of yarns at first positions relative to the knitted yarn portion;
• a second holding unit holding opposite ends of said at least two sets of yarns at second positions relative to the knitted yarn portion;
• and
• a position adjusting unit, connected to said first holding unit and said second holding unit, allowing at least one of said first positions and said second positions, relative to the knitted yarn portion, to be moved other positions, thus varying an intersecting angle of yarns of the knitted yarn portion;
• and
• a vibration unit having a fixed pin and a movable pressure pin, said movable pressure pin being vertically vibrated and subjecting the knitted yarn portion to the vibrations.