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What was the challenge or problem to be solved?
In-line metal detection in production is a critical component of any quality assurance system. Its function is to prevent unwanted metallic particles or components from reaching the final product, minimizing technical, regulatory, and reputational risks.
In this case, the client identified an anomalous situation: certain metal needles used in the process were not detected by the installed systems, while others that appeared equivalent were correctly identified. This inconsistency created a vulnerability in the control system and required a rigorous technical investigation.
Failures in metal detection systems in industrial environments
Failures in metal detection systems are not always caused by equipment malfunction. In many cases, the system operates within its design limits, but the inspected material presents characteristics that reduce the signal generated by the sensors. In this project, the starting point was to confirm that the equipment was properly calibrated and functioning correctly.
The coexistence of detected and undetected needles revealed real technical variability. This variability could be linked to metallurgical, microstructural, or compositional differences affecting behavior under magnetic fields or X-ray radiation. Without a structured analysis, any corrective decision would involve costs without a solid technical basis.
Detection failures are not always caused by equipment, but by the material itself.
The client needed to determine whether the issue was related to the supply, the intrinsic nature of the material, or a deviation from the original specifications. Only with this information could objective decisions be made.
In-line metal detection as a critical quality requirement
In-line metal detection is part of the product quality system design. It acts as a preventive barrier against foreign bodies and is a key element in audits and certifications.
The objective of the project was to ensure that all needles used were detectable under real operating conditions. This required translating in-line behavior into measurable laboratory parameters.
Defining detectability limits prevents recurring production issues.
From a strategic perspective, the client sought to strengthen process robustness without modifying the existing infrastructure. Clear limits had to be defined to validate future supplies before integration into production, thereby preventing recurrence of the issue.
Technical complexity of metal needle analysis
Metal needle analysis required selecting techniques directly related to the physical principles of the installed detection systems. A generic characterization test was not sufficient; properties with direct impact on detector signal had to be evaluated.
The difficulty lies in the fact that small variations in composition or magnetic phase content can produce significant differences in detectability. These variations are not always evident at a visual or dimensional level.
Drawing on its expertise in forensic engineering, INFINITIA designed a comparative study between OK and NOK samples focused on quantifiable parameters. The challenge was to identify technically relevant differences and translate them into criteria applicable to supply control, without oversimplifying the metallurgical complexity of the material.
How was it addressed or what was the solution?
The project was structured around a comparative materials analysis approach aimed at objectively identifying the properties responsible for the differential in-line behavior.
Representative samples were evaluated using techniques aligned with the physical principles governing industrial detection systems.
Structured approach through comparative materials analysis
Comparative materials analysis enabled the simultaneous evaluation of a correctly detected needle and a non-detected one under controlled conditions. This approach eliminated external variables and focused the study on intrinsic material differences.
Comparing OK vs NOK samples reveals real critical differences.
Direct comparison facilitated the identification of critical properties while avoiding irrelevant analyses. A technical strategy was defined exclusively around parameters with direct influence on industrial sensor response.
This approach transformed an operational issue into a technical evaluation based on measurable data, reducing uncertainty and supporting informed decision-making.
Characterization through magnetic behavior evaluation
Since one of the inspection systems operated on magnetic principles, magnetic behavior evaluation was a key stage of the study.
The results showed quantifiable differences between the analyzed needles. These variations directly affected the intensity of the signal generated by the sensor.
The correlation between laboratory measurements and observed production behavior established a direct link to detectability. This analysis provided a clear technical explanation for the phenomenon identified in-line.
Identification of variations through EDX elemental analysis
In parallel, a semi-quantitative surface EDX elemental analysis was carried out to study the chemical composition of the needles. This technique enabled the identification of differences in alloying elements present in each sample.
Small variations in certain elements can modify both magnetic properties and X-ray interaction. Since the sensors were calibrated for a specific range of steels, deviations from that compositional profile directly affected the generated signal.
The study confirmed the presence of relevant differences between detected and undetected needles, explaining the variability observed in production. The combination of magnetic and compositional data provided a coherent technical basis to justify the differential behavior.
