Method for detection of magnetic substances in non-magnetic products and apparatus for the detection

摘要

Disclosed are a method and apparatus for detection of a magnetic substance (10) erroneously included in a non-magnetic product (1). The non-magnetic product (1) such as a sewn product is passed through a high magnetic field (2) in which a magnetic field is applied to the product. The residual magnetization of a magnetic substance (10) such as a broken needle mingled in the product (1) is detected by a sensing unit (3) and a signal of detection is transmitted to a measuring unit (4) to measure the magnitude of detected residual magnetization. The presence or absence of the magnetic substance (10) in the product (1) is determined by a control unit (5) based on the output from the measuring unit (4). Alternatively, a magnetic field may be preparatorily applied to a magnetic substance (10a) having the possibility of being mingled in the non-magnetic product (1a) thereby causing the magnetic substance (10a) to assume a state of possessing residual magnetization. <IMAGE>