Visual inspection is the oldest method of non-destructive testing there is. This is hardly a surprise since our forbearers did not have the instrumentation that we currently possess. They could not have conceived of machines such as an ultrasonic bubbler system or an ultrasonic gantry system. They made do with what they could. However, eventually, they realized that this method of non-destructive testing is not thorough. So the question remains – is there still a place for visual inspection when examining machine components and systems? Here are some of the pluses and minuses of visual inspection.
Pluses of Visual Inspection
- Cost: Obviously, no costs are involved in looking over a part or system for defects. The only equipment that is need is a good set of eyes and someone who is skilled enough to know what he/she is looking for.
- Immediate results: With visual inspection, there is no need to wait for a machine or computer readout. The results are instantaneous when errors are found by inspectors.
- Minimum part preparation: Parts do not need to be readied in order for someone to go over them visually. An inspector can simply assess the part and move on. All that is needed is for the person inspecting the part to have access to it.
- Minimum special skills needed: Visual inspection does not require special training on any kind of equipment. The brain and eyes are the sophisticated tools that an inspector uses.
Minuses of Visual Inspection
- Only the surface of an object can be viewed: Sometimes problems with a part, piece of metal or system is right beneath the surface. Ultrasonic devices can penetrate deep into parts and systems to get a complete view of objects.
- Can only detect larger defects: Flaws that are minute cannot be detected visually. Flaws small enough to miss visual detection can end up compromising the integrity of the entire part or system.
- Cracks and scratches and be misinterpreted: Small flaws that are of no consequence when it come to the functioning of certain parts and systems may be misinterpreted by a visual inspection. A machine can help testers put such benign flaws into perspective.
As you can see, the minuses of visual inspection far outweigh the pluses. And while there still is a limited place for visual inspection, ultrasonic inspection equipment is far more accurate. It may cost more but certainly much is at stake when it comes to the safety of aircraft and the public.