Differences in Resistivity values provide practical means for NDT inspection and process control. Rapid and accurate measurements of electrical resistivity can be obtained with PAC products yielding either bulk or surface characteristics of the component or material being tested.


Resistivity Instrument M-100Applications

  • Thickness Measurement

  • Alloy Sorting

  • Spot Weld Control

  • Flaw Detection

  • Weld Integrity Assessment

  • Stress Corrosion Cracking

  • Crack Depth Measurement

  • Case Hardening


The M100A Metal Inspector

Simple and Effective Nondestructive Testing for Q.C. and Manufacturing of Metals


Materials Characterization

M100A demonstrated testing for metal thickness and the sizing of cracksBecause resistivity values for most metals are already well established, you can use the NDT Automation M100A Metal Inspector to rapidly identify a metal through its resistivity “value”. Surface Conditions, such as oxides or paint, usually do not affect the accuracy of the test because the system acclimates itself to the base material. Technically skilled people or intermediate calculations are not needed. You receive an accurate readout in <1 second.


Fault Detection

M100A demonstrated during a laser weld quality inspectionThe M100A Metal Inspector can also detect cracks or pockets in metals by the increase they cause in the measured voltage. This increase is due to the lengthening of the apparent current path. If the probes are applied on the side of the fault, the increase is very dramatic. But the M100A is so sensitive and accurate that faults on the inside of closed areas, such as pipes, can often be detected and measured by the probes on the outside surface.


Case Hardening

The M100A Metal Inspector makes it possible for the first time to quickly measure the state of transformation of material undergoing case hardening. In the martensitic transformation, for example, the case hardened surface has a large resistivity compared to the soft core or the original material. For typical steels, studies have shown that there is a direct proportional relationship of the hardened material.



The M100A Metal Inspector can give you a good indication of the strength of a spot or laser weld. NDT Automation has correlated weld strength with the voltage reduction measured across resistance spot and various other welds. The underlying principle: the larger the weld nugget and the cross-sectional area of the weld, the lower the voltage measured, indicating greater weld penetration.


The M100A Metal Inspector at Work


M100A shown during a spot weld QC inspectionEasy To Operate

The M100A Metal Inspector is designed for easy use. Simply select the mode of operation (sheet or block), set the dial for thickness or relative percentage value, set your threshold (optional), place the probe on the material and push the button. Readouts are in micro-ohms centimeters, and require minimal operator interpretation. Thickness readouts are in millimetres or inches. The entire setup process can be learned quickly, and is normally performed in less than a minute. Subsequent readings take less than a second.


Applications: Alloy Sorting, Laser/Spot Weld Quality Control, Thickness Measurement, Case Hardening.


The M100A using resistivity to quickly and accurately help you measure brazing quality in pipe joints and fittings. The nondestructive resistivity testing technique can be used to determine the uniformity of filler materials and helps detect areas where voids may exist.

The M100A using resistivity to quickly and accurately measure the thickness of conductive coatings sprayed on metal to metal and metal to non-metal surfaces. This nondestructive testing technique also helps you locate and “size-up” areas where hidden voids, inclusions, or poor adhesion conditions may exists.

The M100A using resistivity to help determine the case depth and hardness of metal. It pulses a rapidly reversing direct current into metal through a 4- point probe, and measures the metal’s resistance to the current flow. Greater Case Depth = Higher Readings.