Wiki

Definition: Optical emission spectroscopy (OES) is an analytical method for the quantitative determination of the chemical composition of metallic materials. Through electrical excitation (spark or arc discharge), elements emit characteristic spectral lines that are detected and evaluated. The method is particularly well established for alloy analyses.

Practical relevance: OES enables the rapid analysis of major and trace elements in steels and aluminium, nickel or copper alloys. Detection limits range from the ppm to the weight per cent range, depending on the element and instrument type. The method is used for incoming goods inspection, melt analyses and positive material identification (PMI). Representative sample preparation is decisive for valid results.

Decision-making perspectives:

• Technical decision-makers: Ensuring specification-compliant alloys and avoiding material mix-ups.
• Purchasing/project management: Binding specification of chemical limit values in accordance with material standards.
• Science: Validation of analytical accuracy and comparison with reference methods (e.g. ICP-OES).
• Insurance/law: Documented material verification in cases of damage or liability.

Typical testing or verification methods: Spark OES, calibration with reference samples, comparative analysis, PMI testing.

FAQ:

• What is OES mainly used for?
• For the rapid and quantitative determination of the chemical composition of metallic materials.

Definition: On-site investigations are technical testing and analysis measures carried out directly on installed components or plant equipment. They enable the assessment of condition, integrity and damage mechanisms without complete dismantling. Mobile testing devices and replica techniques are frequently used.

Practical relevance: Typical methods are ultrasonic testing (UT), visual inspection (VT), mobile hardness testing, PMI and metallographic replicas. On-site investigations minimise downtime and support fitness-for-service or RBI assessments. Documentation and traceability are decisive for later assessments.

Decision-making perspectives:

• Technical decision-makers: Rapid condition assessment and a basis for deciding on continued operation or repair.
• Purchasing/project management: Reduction of downtime costs and targeted maintenance planning.
• Science: Comparison of in-situ and laboratory results in terms of significance.
• Insurance/law: Documented evidence of condition during ongoing operation.

Typical testing or verification methods: UT, VT, MT/PT, mobile hardness testing, PMI, replica metallography.

FAQ:

• What advantages do on-site investigations offer?
• They enable a rapid, economical condition assessment without extensive dismantling or transport.

Definition: Optical measurement methods are non-contact measurement techniques for capturing the geometric, topographic or deformation properties of a workpiece. They use light as the carrier of information, e.g. lasers, white light or camera systems. The aim is precise and rapid data acquisition without mechanical contact.

Practical relevance: The methods include 3D laser scanning, fringe projection, white-light interferometry and digital image correlation (DIC). They are suitable for sensitive surfaces, complex free-form geometries and dynamic measurement tasks. Dimensional deviations, surface parameters or strains are evaluated. Influencing factors are surface reflection, calibration and ambient conditions.

Decision-making perspectives:

• Technical decision-makers: Selection of suitable systems for rapid inline or laboratory testing.
• Purchasing/project management: Assessment of investment costs, accuracy and integration capability.
• Science: Analysis of measurement uncertainties and comparison with tactile methods.
• Insurance/law: Documented geometry verification without component damage.

Typical testing or verification methods: 3D scan, fringe projection, white-light interferometry, digital image correlation.

FAQ:

• When are optical measurement methods advantageous?
• With sensitive surfaces, complex geometries or when rapid, non-contact measurement is required.

Definition: Orientation and location testing is the metrological determination of deviations of a geometrical feature with regard to its orientation or position relative to defined datum features. It assesses location tolerances such as parallelism, perpendicularity, angularity or position. The basis is geometrical product specifications according to DIN EN ISO 1101.

Practical relevance: Location deviations affect the assemblability, tightness and functional reliability of components. The assessment is carried out by comparing the measured geometry with defined tolerance zones, referenced to datum surfaces or axes. Measuring instruments are coordinate measuring machines (CMM), optical 3D scanners or special gauges. Measurement uncertainty and the correct selection of datums are decisive.

Decision-making perspectives:

• Technical decision-makers: Ensuring function-critical alignments and minimising wear or vibrations.
• Purchasing/project management: Unambiguous definition of datum and tolerance specifications in drawings.
• Science: Analysis of tolerance chains and the influence of manufacturing variation.
• Insurance/law: Proof of position or alignment errors in the event of complaints.

Typical testing or verification methods: CMM measurement, optical 3D metrology, evaluation according to the GPS framework of standards.

FAQ:

• What is the difference between form tolerance and location tolerance?
• Form tolerances concern the shape of a feature, location tolerances its orientation or position relative to a datum.