In many industries it is extremely difficult to manufacture products that will be totally immune to cracking and breaking in service, making testing at the point of manufacture, and during use, essential. Cracks can occur in a number of materials such as metals, composites, plastics and minerals, and may indicate manufacturing failure in industries including automotive, aerospace, building, engineering and manufacturing. Non-destructive crack evaluation is essential for quality control and ultimate failure analysis.
Cracks can be identified, and their nature analyzed, through a host of different microscopic techniques including inverted microscopy, stereomicroscopy, metallurgic analysis, digital microscopy and, in some indications, traditional measuring microscopy or an X-ray/CT system.
Timely assessments are needed during production and throughout service to establish whether damage has occurred, If so, the investigator will then need to know where the initiation came through why the fault is there (e.g. a visible casting error or contamination), the size of the crack and the distance from point to point.
More commonly, cracks and structural damage are identified via non-microscopic methods such as resonant frequency, piezoelectric paint sensors and ultrasound. Microscopic techniques can then be employed to provide further clarity and analysis to the damage.
Inverted microscopes are powerful tools in this area as they provide a high level of precision and are strong and durable enough to withstand the weight of an entire engine shaft or gear box, allowing cracks to be identified in situ. Alternatively, damaged parts can be cut out for remote examination then mounted and analyzed under high resolution magnification using digital microscopy and the software associated with this mode of analysis.
X-ray and CT is the most advanced system and is often used in complex carbon-fibre material for innovative aerospace applicatons. WIth this system you can gain full insight into the inside of materials and structures.
Key terms and techniques include: stereomicroscopy, inverted microscopy, digital microscopy, software, metallurgy