The job is clamped between two copper contact pads by operating pneumatic lever as well as mechanical. Magnetic fluid is flowed over the job using lever operated hand hose and while the fluid is still flowing a high current shot of desired strength is passed by pressing a foot switch. Duration of current flow which is controlled by electronic timer is generally 1/2 to 1 sec. The job is then inspected for longitudinal cracks using black light lamp. The cracks are seen as brilliant yellowish green lines. |