TAZ GmbH successfully completed a large-scale project for a renowned automotive supplier in the areas of mix-up testing, material sorting, and Positive Material Identification (PMI) testing. A significant number of assembly parts made from materials C15 and C45 needed to be differentiated. For this, mix-up testing and material sorting through mobile spark spectrometry analysis were used.

Due to the high volume of parts requiring sorting, we operated in a two-shift system, utilizing two mobile spark spectrometers in parallel. Accurate differentiation between the materials, based on carbon concentrations of 0.15% and 0.45%, required spark spectrometers with high repeatability and precision. Our inspectors are highly trained and qualified. Each sample surface was lightly polished and then precisely analyzed. Certified reference samples for C15 and C45 grades were used to continuously verify analysis results. If carbon concentration discrepancies exceeded 0.04% from the target values, the spectrometers were recalibrated and then rechecked.

Both spectrometers were equipped with calibration certificates from TAZ Service Technology.

The challenge in this mix-up testing and material sorting project was the large number of parts to inspect within two weeks. With a team of four inspectors working in two shifts across two spectrometers, the PMI testing was completed successfully and on schedule.

General Information on Mix-Up Testing / Material Sorting / PMI Testing In general, mix-up testing and material sorting for metallic materials can be performed using two different methods:

Mobile Optical Emission Spectroscopy (OES) in spark or arc mode
Mobile X-Ray Fluorescence (XRF) analysis

Advantages of Mobile Spark Spectrometry:

Capable of analyzing all essential elements, including carbon
Relatively low detection limits, reaching down to the ppm range
Simple operation
Material sorting results can be indicated with a green-red light system
No state-issued qualification required for the operator

Disadvantages of Mobile Spark Spectrometry:

Surfaces must be ground for carbon analysis in spark mode. Carbon analysis is not possible in arc mode
Leaves a spark mark on the surface
Duration is approximately 30 seconds per test

Advantages of Mobile X-Ray Fluorescence (XRF) Analysis:

Completely non-destructive testing
Short analysis times (sometimes only 1-2 seconds)
Material sorting results can also be displayed with a green-red light system

Disadvantages of Mobile X-Ray Fluorescence (XRF) Analysis:

Carbon analysis is not possible
Limited capability for analyzing light elements like phosphorus and sulfur
A formal qualification is required for the operator
Lower detection limits
Improper use can result in X-ray radiation leakage