Material defect
Material defects are defects in or in materials or materials that either represent optical, aesthetic or functional damage themselves or can lead to consequential damage if the defective material is used further. Correspondingly, material defects can also be differentiated into visible and hidden material defects.
Causes of material defects can be inherent in the material or they can be production-related. A material defect can therefore be based on incorrect actions through further processing , but it can also be attached to the material itself ( inclusion of foreign bodies).
Manufacturing-related material defects can be traced back to production defects.
Examples of immanent material defects are:
In the current DIN ISO 10110 for the creation of technical drawings for optical elements and systems, Supplement 1 u. a. A comparison of the current standard to the earlier DIN 3140 in which tolerances or limit values for the following material defects are dealt with:
- Part 2 stress birefringence
- Part 3 bubbles and inclusions
- Part 4 inhomogeneities and streaks
If properties such as porosity or inclusions in the material are undesirable, these can also be regarded as intrinsic material defects. In addition to streaks in glass, production-related material defects would e.g. Belly
- Weaving defects in textiles
- Kalkspatz in ceramics
To check for material defects, metallurgy , measurement and testing technology offer various test methods and test instruments such as the fluxgate magnetometer , the impact hammer , sonography , ultrasound testing or reflected light microscopy .