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In the field of nondestructive testing (NDT), the main challenges that inspectors face are accessibility and image resolution. Gaining access to the test site is often a challenge because the access openings for inspection are very small. Furthermore, the twists and turns that need to be navigated and the distance from the opening to the inspection site only compound the problem. Image resolution is also a critical factor for successful inspection. If a hard-to-see blemish, hole or incomplete weld is not detected during the manufacturing or maintenance process, equipment is more likely to fail out in the field-inflicting its toll in downtime, added repair costs and frustration.
The ResultsWith borescopes, LPI and blending scopes, an inspector can discover small problems before they become big ones that lead to downtime, equipment failure and product recall. When a flaw is discovered in the field or during routine maintenance, the inspector can easily correct the problem onsite, thereby saving money, increasing productivity and reducing waste.
With borescopes, LPI and blending scopes, an inspector can discover small problems before they become big ones that lead to downtime, equipment failure and product recall. When a flaw is discovered in the field or during routine maintenance, the inspector can easily correct the problem onsite, thereby saving money, increasing productivity and reducing waste.
In a manufacturing application, the staff needed to inspect a weld on the inside of main drive shaft for a gas turbine engine. They use a borescope that is mounted to a table. They then bring the part over the borescope and rotate the part 360 degrees to inspect the weld. They perform this inspection using both white light, then switch to UV to ensure the weld is complete and meets their strict quality control requirements. The UV makes any imperfection in the weld much easier to see.
Other applications include inspection of pipes to ensure they are cleaned between processes. This is common in many industries where the user conveys material through large pipes for processing, which can apply to medical, food, plastics or any other material. These materials will change from time to time, thus the pipes need to be cleaned and inspected to ensure that no material has been left in the pipes. With this type of application we turn to the larger 1 to 1.5 inch diameter pipe camera that has a 100-foot pushable cable. This allows the inspector to clearly view the inside of the pipes to ensure there is no foreign matter left in the pipes between process changes.
Tech TipsWhen looking for cracks that are running in line with the fastener row, you can rotate the probe 90 degrees and scan in the same way as a fixed sliding probe.
The Dual Frequency Eddy Current testing technique offers the ability to still use sliding probes to scan over countersink rivets and detect cracks, while filtering out noise from the varying rivet conditions caused by the alodine rivets.
NDT technicians armed with an eddy current instrument and a sliding probe will be able to inspect most aluminum skinned aircraft.