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Laboratory Results: Convincing Precision and Reliability
Initial feasibility studies conducted in collaboration with leading electrical steel producers showcased the EMG SOLID® DFT​​​​​​​’s exceptional capabilities. Laboratory tests involved samples coated with various insulating varnishes from ASTM classes C3 to C6. The system demonstrated high sensitivity, accurately detecting varnish thicknesses ranging from 0 to 10 µm. Measurements were performed on standardised sample sheets using the EMG SOLID® LIF system, which ensured optimal calibration and adaptation to different varnish types.

The results were remarkable. The system displayed a clear correlation between LIF intensities and varnish thickness, with minimal deviations. Even the thinnest layers were detected with high precision, and the technology effectively differentiated between coated and uncoated surfaces. Additionally, calibration procedures using reference samples validated the system’s consistency, confirming its reliability for diverse production conditions.

Inline Results: Consistency Under Real Production Conditions
Transitioning from the laboratory to real-world production environments, the EMG SOLID® DFT​​​​​​​​​​​​​​ continued to deliver outstanding results. Inline tests were conducted in various electrical steel production lines, comparing the system’s performance against traditional BBS methods. The findings highlighted the superior sensitivity and accuracy of the EMG SOLID® DFT​​​​​​​.

One of the most important outcomes was the system’s ability to maintain precise measurements across different strip temperatures, ranging from 50 °C to 150 °C. This temperature resilience ensures consistent performance even immediately after the drying furnace. 

The system’s rapid detection capabilities allow for early identification of coating anomalies, significantly reducing material waste and improving overall production efficiency.

Inline tests revealed that the EMG SOLID® DFT​​​​​​​ could detect minute fluctuations in coating thickness, down to 0.1 µm, outperforming both BBS and infrared (IR) methods. A prominent example is shown in the illustration. In principle, the small change in the coating thickness of just under 0.1 µm (left y-axis) could also be identified by means of a statistical evaluation of the IR data (right y-axis). However, the noise in the IR measurements is so high that the importance of the statement is significantly lower.

The data collected during these tests demonstrated a strong correlation with reference measurements, confirming the system’s robustness and accuracy under continuous production conditions.

Technical Key Data at a Glance
The EMG SOLID® DFT​​​​​​​ system is engineered to meet the demanding requirements of modern electrical steel production. Key technical specifications include:

• Measuring Method: Laser-Induced Fluorescence Spectroscopy 
• Number of sensors: 1 per strip side
• Measured Variable: Dry film thickness of varnish in µm
• Measuring Range: 0 to 10 µm
• Measuring Accuracy: ± 10 % of the measuring range end value
• Repeatability: 0.1 µm
• Resolution: 0.9 % of the measuring range end value
• Operating Temperature: +5 °C to +150 °C
• Measurement Frequency: 10 kHz
• Traversing Speed: 0.5 m/s

Benefits of the EMG SOLID® DFT System
The EMG SOLID® DFT​​​​​​​ offers numerous advantages over traditional coating measurement methods:

1. Non-Radioactive Technology: Eliminates the need for hazardous isotopes, enhancing safety and compliance with environmental regulations.
2. High Sensitivity: Detects coating thickness variations as small as 0.1 µm, providing detailed insights into production quality.
3. Temperature Resilience: Maintains accuracy across a wide temperature range, supporting flexible installation points within the production line.
4. Real-Time Monitoring: Enables immediate detection of coating defects, reducing material waste and minimising production downtime.
5. Ease of Integration: Compact sensor design allows for easy installation in existing production lines without significant modifications.
6. One sensor only: Compared to classic beta backscattering solution the EMG SOLID® DFT​​​​​​​​​​​​​​ method is a direct measurement with only one measuring spot and not a comparative measurement with two measuring spots (uncoated and coated).

These features and benefits enable the system to perform reliable, high-precision measurements, making it an ideal choice for inline applications in silicon steel production.

Conclusion
The EMG SOLID® DFT system represents a transformative leap in insulating varnish thickness measurement for electrical steel production. Its combination of cutting-edge LIF technology, exceptional precision, and operational efficiency sets a new standard in the industry. For production engineers, quality managers, and decision-makers seeking to enhance process reliability and product quality, the EMG SOLID® DFT is an indispensable tool.

To learn more about how the EMG SOLID® DFT

can benefit your production processes, contact EMG’s sales team via www.emg.elexis.group/en/, our product manager

Timo Gemmer, or visit our product webpage for detailed information and support.

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