What is the minimum viewing angle requirement for visual inspection?

What is the minimum viewing angle requirement for visual inspection?

• A. 20°
• B. 40°
• C. 30°
• D. 50°

Answer: (C)

To see surface defects clearly in visual inspection, you want to view the surface obliquely so lighting can highlight irregularities. A viewing angle from the surface of about 30 degrees provides enough oblique lighting and shadowing to reveal pits, corrosion, or cracks. Angles smaller than this tend to produce glare and mask defects, while much larger angles reduce lighting effectiveness for detecting surface irregularities. So, 30 degrees is the minimum that reliably enhances defect visibility under typical inspection lighting.

To see surface defects clearly in visual inspection, you want to view the surface obliquely so lighting can highlight irregularities. A viewing angle from the surface of about 30 degrees provides enough oblique lighting and shadowing to reveal pits, corrosion, or cracks. Angles smaller than this tend to produce glare and mask defects, while much larger angles reduce lighting effectiveness for detecting surface irregularities. So, 30 degrees is the minimum that reliably enhances defect visibility under typical inspection lighting.