Visual Inspection

A basic distinction is made between direct and indirect visual inspection.

The direct visual inspection is an inspection in which the beam path between the inspection surface and the eye of the inspector is not interrupted. In addition, direct visual inspection is subdivided into

• testing without aids (also known as "unarmed eye"), where the naked eye is used exclusively for testing

• inspection with aids, in which, for example, a magnifying glass, mirror, microscope or flashlight is used.

In contrast to direct visual inspection, in indirect visual inspection the beam path is interrupted between the test surface and the inspector's eye. This is the case, for example, when testing with the aid of a camera.

A major advantage of visual inspection is that the implementation hurdles are comparatively low. A simple visual inspection with the naked eye already enables a high error detection rate.

Another advantage is that you need very little equipment. In principle, the inspector's eye is sufficient for many scenarios. This low hurdle makes visual inspection ideal for spot checks.

Visual inspections are also part of numerous standards. If you use them, this automatically results in at least partial conformity with standards.

Another major advantage is that you proceed non-destructively. You do not have to interfere with the product. You check what you can see.

If you use advanced technologies such as cameras and digital analysis tools, you also have the option of automatically documenting defects, creating precise defect assessments and using recorded data for subsequent analysis and optimization.

Where there is light, there is also shadow and this can actually distort the result of a visual inspection. In general, it has the major disadvantage that it is dependent on many "environmental conditions". Not every tester delivers the same results; changing light conditions, fluctuations in concentration and fatigue can affect the results. In the worst case, this can lead to errors.

If you opt for a technically supported visual inspection, you will initially have to reckon with higher costs for cameras and analysis software.

A visual inspection can reveal any defects that are visible to the eye. These can include

• scratches

• cracks

• dirt

• assembly errors

• burr formation

• Color changes

• Roughness

However, you cannot see inside the components; in a sense, you remain on the surface.

In addition to inspection with the naked eye, other methods have been established with which advanced visual inspections can be carried out. These include

Camera systems are used to detect faults or defects quickly and reliably.

This is a method for determining the exact 3D position or geometry of an object by measuring light beam angles.

This method involves capturing and evaluating measurement data by analyzing photos or image sequences in order to create 3D models.

This measuring method uses the time delay of light phases to analyze distances or surface structures.

This is a high-precision technique that uses the superposition of light waves to measure surface changes or deformations.

The aim of a visual inspection is to detect safety-relevant damage at an early stage. This is intended to reduce the scope of downstream inspections - e.g. using measurement technology.