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Inspecting Areas Close To Edges


Several techniques can be used to eliminate or reduce the edge effect that affects or even prevents the inspection on areas close to edges, fastener heads, etc.

1. Shielding

Shielding is the most often used technique to avoid edge effect. Ferrite is the best material used and reduces the sensitive area to the
internal diameter of the shield. At lower frequencies the eddy currents will propagate slightly beyond the shield diameter.

2. Differential Coils

The use of differential coils can be helpful to avoid external interference such as edge effect. With the coils aligned to keep the same distance to the edge, it is possible to inspect sometimes even with an overlap.

3. Maintaining a Constant Distance

By using a guide it is possible to keep a constant distance to an edge or another object such as a fastener head (see Figure 1 and 2).

Figure 1

Figure 2



Figure 3

4. Using Directional Probes

Directional probes can be useful as their sensitivity at 90° is very low. The reflection sliding probes with transparent lenses are the best examples of this (see Figure 3). Because of low sensitivity at 90° they ignore edges and joints between two plates or skins. A straight edge can be useful as a guide (see Figure 4).



Figure 4

5. Using Directional Probes Across the Edge or Joint

The signal produced by the joint or edge can often be differentiated from the defect (see Figure 5).

Figure 5

6. Adding Another Piece of Similar Type Metal to Probe

By adding a piece of similar type metal to the probe, it is possible to establish a path for the eddy currents and sometimes use it as a guide as well (see Figure 6).

Figure 6

Olympus IMS

Products used for this application


Pencil Surface Probe

Pencil surface probes are general purpose plastic-tip probes used for surface or near-surface crack detection. They are available with various coil configuration and connector options. Pencil surface probes feature an adjustable collar for greater stability.

Bent Shaft Surface Probes

Bent shaft surface probes are general purpose stainless-steel probes used for surface or near-surface crack detection. They are available in a variety of sizes, and with various coil configurations and connector options.

Flexible Shaft Surface Probes

Flexible copper shaft of these probes can be bent to various shapes. Designed for general surface crack detection, flexible surface probes are available in a variety of lengths, and with various coil configurations, drops, and connector options.

All Other Surface Probes

A specialized probe series including the Pencil 3551l probe, Blade probe, Plastic-Tip probe, Finger probe, and Spring Loaded probe.

Rotating Stainless Steel Scanner Probes

The rotating stainless steel scanner probes section includes a range of all-stainless-steel probes, including the standard series and the SEU series.

Ring/Donut Probes

Ring/Donut probes are made to fit various fastener head diameters. Their principal use is for subsurface crack detection with the fastener in place. They are available in both bridge and reflection configurations.

All Other Scanner Probes

The other rotating scanner probes section includes a variety of specialized scanner probes, such as the Adjustable X type series, the Adjustable Y type series, the Countersink series, and the Countersink Stainless Steel series.

Angle Shaft Surface Probe

30° or 45° tip, stainless-steel shaft. Designed for general surface-crack detection, these probes are available in a variety of lengths, and with various coil configurations, drops, and connector options.

Straight Shaft Surface Probes

Straight stainless-steel shaft. Designed for general surface crack detection, these probes are available in a variety of lengths, and with various coil configurations and connector options.

Manual Bolt Hole Probes

Manual bolt hole probe coils are positioned at right angles to the shaft direction. These probes are rotated by hand to inspect holes with the fasteners removed. Standard (fractional and metric) and custom diameters are available with either absolute or differential coils.

Rotating Plastic Scanner Probes

The rotating plastic scanner probes section features a variety of expandable plastic-tip probes and stainless-steel backshell probes, including the SUB series, SPO-5965 series, SPO-3564 series, and standard series.

Eddy Current Probes

Eddy current probes consist of the acquired brands of Nortec and NDT Engineering. We offer more than 10,000 standard and custom designed eddy current probes, standard references, and accessories.

Spot Probes

Spot probes are used for discovering flaws both on and below surfaces. Their large coil diameter and low frequency operation are advantageous for scanning larger areas, and providing an increased detectable flaw size; typically equal to one-half of the probe diameter.

Weld Probes

Weld probes are designed to inspect ferrous welds. They provide a cost-effective alternative to magnetic particle inspection, which requires the part to be prepared (cleaned) prior to inspection.

Right Angle Surface Probes

90° tip, stainless-steel shaft. Designed for general surface crack detection, these probes are available in a variety of lengths, and with various coil configurations, drops, and connector options.

Conductivity Probes and Standards

Conductivity probes are designed for sorting non-ferrous metals and determining heat treatment condition or damage.

Sliding Probes

Sliding probes are specifically designed to inspect rows of fasteners. They operate in reflection mode and are used to find surface and near-surface flaws. They come in adjustable types, which are able to accommodate different fastener sizes, and fixed types, which are usually procedure specific.

NORTEC 600NEW

The new NORTEC 600 incorporates the latest advancements in high-performance eddy current flaw detection into a compact, durable unit. With its vibrant 5.7 inch VGA color display and true full-screen mode, the NORTEC 600 produces user-selectable, highly contrast eddy current signals.

OmniScan MX ECA/ECT

Performs eddy current array testing inspections. The test configuration supports 32 sensor coils (up to 64 with an external multiplexer) working in bridge or transmit-receive mode. The operating frequency ranges from 20 Hz to 6 MHz with the option of using multiple frequencies in the same acquisition.
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