Criterion NDT’s eddy current test systems provide a fast, clean way to verify proper thread and feature manufacturing. Eddy current thread and feature test systems are used to find:

. The rotor iron circuit is perfectly laminated so that eddy currents are negligible. The rotor slots have radial sides as shown in Fig.1. The current density has only one component along z-axis. The stator windings are fed with sinusoidal current of angular frequency ωs. Eddy current testing uses the principle of electromagnetic induction to detect flaws in conductive materials. An excitation coil carrying current is placed in proximity to the component to be inspected. The coil generates a changing magnetic field using an alternating current, which interacts with the component generating eddy currents. Equivalent current sheet model of one coil in slots. (a) Cross sectional area of SPMSM. (b) Stator current assumed to be on the slot opening as a current sheet. (c) Magnitude of stator current distribution. Eddy Current Loss and Temperature of the Magnets 1289.

• • Partial and damaged threads
  • Oversized and undersized threads
  • Broken taps
  • Missing holes
  • Incorrect threads
  • Missing or malformed features (such as keeper grooves, key ways, splines, etc.)

Similar to structure testing, this type of eddy current test compares a known good part with a thread or feature under test. If the two are different, the eddy current instrument signals an alarm condition and the suspect part can be sorted out.

Eddy current thread and feature testing offers many advantages over other inspection methods. Thread gauges are time and labor intensive; vision systems require parts to be cleaned and spun, and are reliant upon the installation of good lighting systems.

By comparison, eddy current testing is fast—often completed in less than a second for inspection of all threaded holes on a part. The inspection method is also comprehensive, allowing for in-line testing of 100% of parts in production.

In addition to offering the CR-11, ST-11, and InSite eddy current test instrumentation for thread and feature verification, Criterion NDT manufactures a variety of standard and custom thread probes, reinforced with stainless steel housings to prevent wear and purpose-built for thread and feature testing. Visit our Probespage for more details on the quality and purposes of our eddy current probe offerings.

Eddy Current Loss Pdf

Whether using single thread probes positioned with a robot arm, or using a conventional in-line material handling system with multi-probe test fixtures, the instrument’s industrial I/O can interface to PLCs used to control production line feeders to further automate the inspection process. See our material handling section for more information.