In today’s highly demanding steel and aluminum industries, maintaining the integrity and performance of rolls is critical for ensuring consistent product quality and reducing downtime. Automatic inspection systems by LISMAR, an Ascential Technologies brand, are designed to meet these challenges by combining multiple advanced non-destructive testing (NDT) technologies. By integrating Eddy current technology (ET), surface wave technology (SW) and ultrasonic technology (UT), LISMAR provides a comprehensive solution for detecting both surface and subsurface defects with high precision and reliability.
Below, we examine the techniques and benefits of each of the respective NDT technologies and how we can drive further efficiencies by bringing them all together.
Surface Defect Detection: Eddy Current Technology
ET is an electromagnetic technique that operates on the principle of inducing eddy currents into conductive materials and measuring their response to detect irregularities. It’s one of the core methods used in LISMAR systems for surface inspections.
This technology is particularly effective for detecting defects directly on or near the surface of rolls, ensuring that even minute imperfections are identified before they can impact production quality.
Other key advantages of ET include its:
- High sensitivity to small surface defects such as cracks, pores and inclusions
- Fast inspection speeds, making it ideal for automated systems
- Non-contact measurement, reducing wear and maintenance
Surface Crack Detection: Surface Wave Technology
To further enhance surface inspection capabilities, LISMAR systems incorporate SW, a method that uses ultrasonic surface (rayleigh) waves that propagate along the material’s surface. SW is important because it provides an excellent means for detecting closed surface cracks, even those that are difficult to detect by other methods. Additionally, it’s sensitive to shallow defects that may not generate strong signals in conventional ultrasonic testing. Complementary to ET, SW also improves overall detection reliability.
By combining ET and SW, LISMAR ensures robust and redundant inspection of surface conditions, minimizing the risk of undetected defects.
Subsurface Inspection: Ultrasonic Technology
While surface inspection is essential, many critical defects originate below the surface. For this reason, UT is impactful by detecting internal flaws within rolls. UT works by transmitting high-frequency sound waves into the material and analyzing the reflected signals.
This technology ensures that hidden defects, which could lead to catastrophic failures if left undetected, are identified early in the lifecycle of the roll. Specifically, UT excels at:
- Detection of internal cracks, inclusions and voids
- Accurate depth measurement, allowing precise localization of defects
- Reliable inspection of thick materials and large rolls
A Combined Approach for Maximum Reliability
The true strength of LISMAR’s automatic inspection systems lies in the integration of these three technologies. Integrating ET and SW results in a more comprehensive surface inspection while UT delivers reliable subsurface defect detection.
Overall, this multi-technology approach delivers higher detection probability, reduced false calls and improved confidence in inspection results, while setting a benchmark in roll inspection by combining technologies into one powerful platform. This comprehensive solution ensures that both surface and subsurface defects are detected with maximum accuracy, helping manufacturers maintain the highest standards of product quality while reducing operational risks.
To further increase efficiency, LISMAR’s systems are fully automated, enabling:
- Consistent inspection quality independent of operator skill
- High throughput suitable for industrial environments
- Integration into production and maintenance workflows
This automation not only increases efficiency but provides traceability and data logging for quality control and predictive maintenance.
By investing in advanced inspection technologies like LISMAR’s, companies can extend roll lifetime, optimize production processes and ultimately achieve greater reliability in their operations.
