Visual Testing/Visual Inspection is one of the most extensively used test among the Non Destructive Tests. It is very simple test, can be carried out easily. It is also very economical. Even if the components are to be examined using other NDT methods, an effective visual testing/visual inspection must be carried out first. The visual test helps in revealing the surface defects and lead towards an instant rejection of the component, ensuring both time and money saving.
It has become essential to examine the existence of finer defects. And therefore, the visual methods are developed to a very high degree of precision. With the arrival of computers and microprocessor, the visual examination can be performed very effectively at the lower costs. Automatic accept/reject choices and image processing patterns recognition are utilized when many components are to be examined.
The main procedure used in visual NDT includes the illumination of the test sample with light, generally in visible place. The sample is inspected either through the eyes or using light sensitive equipment. The equipment needed for inspeciton is simple, but there must be adequate light, which is essential. Moreover, the surface of the sample must be cleaned before being assessed.