1. Visual Inspection: Use the human eye to perform an inspection to see if there are any visible scratches on the surface of the part.
2. UV Inspection Lamps: The use of UV inspection lamps can help to detect small scratches on the surface of the parts, as scratches usually have a different reflective effect.
3. Magnifying glass or microscope: Using a magnifying glass or microscope can be used to observe and identify fine scratches.
4. Infrared Thermography: Infrared thermography can be used to determine the presence of scratches by detecting changes in heat on the surface of the part.
5. High Resolution Cameras: Using a high resolution camera you can take pictures of the part surface and use image processing software to analyze and identify scratches.
All of these devices can be used for the detection of cosmetic scratches on parts, and the exact choice depends on the size and detail of the scratch.