Trait 1: The outer diameter of steel wire thread insert at free state, compared with the diameter of thread aperture, is longer .While, the former will be inserted the latter .When assembled , the outer diameter getting smaller through the wrench strength , it is circumvolved into the thread aperture and will be firmly fixed there , never move to the bolt¡¯s move. A high precision inner thread in accordance with the corresponding standards forms , superior to that by wire wimble.
