Increased process safety and efficiently through Automated Defect Recognition (ADR) in X-ray inspection

Especially automotive manufacturers with a very high production volume demand interaction free in-line systems with Automated Defect Recognition (ADR). This reduces personnel costs and lowers the chance of human errors during the inspection process. Automated inspection systems have to comply to international quality standards like ASTM, VDI, EN etc. and the demanding company standards of VW, BMW, Porsche etc. As the production process of such parts is already completely automated systems have to be designed for 24/7 operation without human interaction, while offline stations are used to train the inspection sequences or review the results. This leads to a completely decoupled procedure for 100% system uptime.
Typical ADR applications are the detection of porosities, inclusions or cracks in casting parts. It is possible to define certain ROIs and check defect metrics like defect density, defect distance, defect size, defects per area and many more. Thresholds can be defined dynamically. Training of the system does not require any programming skills and can be done through local supervisors. This drives down production costs and reduces the inspection bottleneck, while increasing the reliability and process safety. An integration to Industry 4.0 factory solution allows full traceability of the inspection process on a part level.
More demanding tasks like automated measurement, completeness or density checks can be performed through the unique VAIP (VisiConsult Automated Image Processing) module. Complex test sequences can be performed on static images or in real time. Example applications: The behavior of heat pumps under different temperatures and completeness checks of valves.

Small Controlled Area Radiography – Fundamentals and Technology Advancements

Radiographic testing (RT) is one of the most efficient and economic NDT methods for volumetric inspection; ensuring safe, reliable construction and ongoing use of critical infrastructure around the world. The penetrating radiation from isotope based gamma ray and accelerator based x-ray sources provide a unique mechanism for creating an image based on the differential absorption of photons in a sample. Unfortunately, the mechanisms of photon radiation interactions with matter that allow for weld quality inspection, measurement of corrosion/erosion in pipe wall, etc. create negative externalities in many environments where RT is often performed.
• Gamma radiation interferes with critical safety and process control systems. Examples include visual flame detectors (VFDs) and nuclear level gauges, switches, density gauges, etc. These systems cannot differentiate the gamma rays from a radiography source and the UV/IR photons from a fire or gamma rays from 137Cs sources used in many nuclear gauges.
• ALARA – The ever-increasing emphasis on reducing occupational exposure and exposure to members of the general public often requires RT to be performed in shooting windows or during off-shifts reducing overall inspection efficiency.
SCAR or Small Controlled Area Radiography is the concept of controlling the radiation utilized for RT allowing for radiographic inspection without restrictive shooting windows (24/7 radiography concept), in close proximity to other trades, and without impacting critical sensor systems. This paper describes the fundamental principles for achieving Small Controlled Area Radiography with an emphasis on the use of 75Se and innovations in SCAR equipment enabling advanced SCAR techniques. Practical SCAR applications covered include:
• Near nuclear gauges and visual flame detectors – typically <5 uSv/hr
• Close proximity to members of the general public – <2.5 uSv/hr exclusion zone at 2 meters
• Flash dose
• Rope access

Safety Performance of Se-75 Radiography Sources

Se-75 is a versatile gamma radiography nuclide. Its energy is optimum for the range of materials and thicknesses of common interest to gamma radiographers and it is an excellent choice for Small Controlled Area Radiography (SCAR). Its use is continuing to grow with the introduction of new Se-75 exposure devices, enabling the SCAR technique to be implemented simply, safely and effectively. SENTINEL has developed an optimized, third-generation Se-75 source using metal-alloy selenium for use with both SCAR and conventional exposure devices. This source has improved near-spherical focal geometry and is available in higher activities up to 120Ci. Its focal dimension of 3.5mm is the smallest on the market at this activity level.
• Highest specific activity and smallest focal dimension: better images
• Inherent safety with source tested to 1250C – intrinsically safer
A radiological incident in Europe in 2016 resulted in the rupture and leakage of 75Se from a commercial source that had been made using elemental selenium. Due to the ensuing high financial and commercial costs associated with such an incident, it prompted SENTINEL to carry out a new series of high temperature integrity tests to verify the superior performance of SENTINEL’s proprietary metal-alloy source technology and to compare the results with sources made using elemental selenium. This paper describes the thermal test program and discusses the implications for the safety and performance of gamma radiography using Se-75.

Analysis and development of inspection procedures based on Computed Tomography and Digital Radiography on Aerospace Additive Manufactured Parts

The aerospace industry is increasingly demanding complex geometries to obtain low weight structures. At the same time, Additive Manufacturing (AM) is a powerful technology which allows a high degree of geometrical optimization. However, requirements on the inspection of the entire volume, including inner surfaces, restrict very often the design process. In this context, X-Ray computed Tomography (XCT) is capable to measure both inner (lack of fusion, voids, cracks, etc) and outer indication (cracks and also geometrical deviations). On the other hand, although Digital Radiography (DR) presents reduced information if compared with XCT, this technique can reduce both lead time and costs.
This work presents a detectability analysis by XCT and DR of typical AM defects. The detectability of voids and cracks is investigated on AM samples, including an analysis of the influence of part thickness on the inspection contrast. At the same time, standards for RD inspection have been developed including induced indications fabricated directly by the variation of AM processing parameters (voids) and through design (cracks), which have been contrasted with XCT. Finally, dimensional analyses of complex geometries are presented as well.

Cold Cathode Microfocus X-Ray tubes Based on Nanostructured ZnO

X-rays find applications in medical diagnostics, airport security inspection, and nondestructive testing in industry. However, the technology for generating X-rays has essentially been the same since the birth of the Coolidge tube for about 100 years ago, and the same physics for generating X-rays is still broadly in use today.
In the past two decades or so, the emergence of new classes of nano-materials has boosted advancement in fundamental research and applications of field emission cathodes in X-ray generation. Most of the X-ray tubes based on CNT cathode disclosed or published in literature seems to have too low emission current to replace the hot cathode tubes in applications. This can in principle be remedied by increasing the area of the cathode. However, larger cathode area will naturally lead to larger focal spot size and poorer spatial resolution of the image, an unwanted consequence. It is well known that the smaller the focal spot size, the higher the spatial resolution of the image. Likewise, for the hot cathode X-ray tubes, in order to decrease the focal spot size to the so called micro focus range, strong electromagnetic lenses are used to focus the electron beam traversing in the space between the cathode and the anode. Consequently, the region of the anode under the focal spot may be subjected to too high thermal load to maintain being solid.
In this paper, we report our work on the development of micro focus tubes by introducing a different microfocus solution combining with nanostructured ZnO cold cathode and/or hot cathode. These tubes are glass sealed and backward compatible. The key performance parameters are presented and evaluated, such as focal spot size, power output and anode power density. Comparison is made between these tubes and some of the microfocus tubes in the market.

X-ray detector for maximum efficiency in the energy range above 400keV – are 101dB worth the additional effort?

Digital X-ray technology represents a reliable, non-destructive quality control procedure for mainly safety-related intermediate and final products.

The main advantage of line detector arrays (LDAs) for higher X-ray energies is a reduction of the unwanted scatter radiation that is superimposed onto the useful information of the X-ray image. Due to combined beam hardening and scatter correction by software, digital detector array (DDA) images have come closer to traditional LDA images in the energy range above 400keV. For energies above 1MeV LDAs are still the first choice for most applications.
On the other hand, LDAs also stand to gain in quality from improved geometry, more efficient scintillators, low-noise electronics and improved calibration procedures. For larger objects the dynamic range is the most important factor and here LDAs can gain from the much higher efficiency of the scintillator and well-adapted electronics with more than 100dB dynamic range.

The presentation will show the results of a five years technology study at YXLON. Emissions from the X-ray source and the deposition of energy in the scintillator are studied using Monte Carlo simulations. In a second step the efficiency of the photodiodes and the noise of the electronics are considered, in order to evaluate the maximum possible dynamic range. Side effects like detector internal scatter radiation will be considered and physical reduction methods presented. Finally, images acquired with an LDA designed with use of the simulation know-how and all collected experiences will be shown and compared with DDA images, proving that with the new technology, there is yet again a large number of applications where LDAs are the first choice of detector for X-ray energies above 400keV.

Feasibility study of a new X-ray based measurement method using aluminium cast parts.

Applications of industrial computed tomography (CT) to the field of dimensional measurements have been evolving rapidly during the last decade. In multiple fields of industry, along with the detection of defects and flaws in workpieces, dimensional quality control is nowadays in high demand. In many cases, quick decisions based on measurement data should be made about the acceptance or rejection of parts. Thus, one current issue is speeding up CT scanning while maintaining the required measurement data quality. Although rapid CT acquisition and reconstruction modes already exist, the accuracy of these quick measurements is very often compromised by such a speed-up and could be insufficient. To overcome this issue, we propose a novel projection-based measurement strategy based on a typical industrial CT setup. In our method fewer radiographic views are acquired compared to typical CT scans leading to a reduction of acquisition time. To ensure the desired accuracy of the measurement, features of interest and favourable projections are selected prior to the actual CT acquisition. Besides the improvement in scanning time a further benefit of the projection-based approach is that reconstruction artefacts and their influence on the measurements could be reduced. The paper shows the feasibility of such an approach and discusses its possible advantages and disadvantages. First results acquired at aluminium cast parts using a real CT setup and respective simulations made with BAM software aRTist will be presented.

Current Developments in Digital Radiography and Computed Tomography from nm to macro scale

Digital Detector Arrays enable an extraordinary increase of contrast sensitivity in comparison to film radiography. Computed radiography with phosphor imaging plates substitutes film applications. The increased sensitivity of digital detectors enables the efficient usage for dimensional measurements and functionality tests substituting manual maintenance. The digital measurement of wall thickness and corrosion status is state of the art in petrochemical industry. X-ray back scatter techniques have been applied in safety and security relevant applications with single sided access of source and detector. First inspections of CFRP in aerospace industry were successfully conducted. Computed tomography (CT) applications cover the range from nm to m scale. Small structures of integrated circuits are visualized and measured with lens based CT-systems or at synchrotrons. Phase contrast imaging provides enhanced structure contrast in micro radiography and micro CT. The scope of typical CT applications changes from flaw detection to dimensional measurement in industry substituting coordinate measurement machines. Mobile computed tomography is applied for in-service radiographic crack detection and sizing of welded pipes in nuclear power plants and for NDT of large CFRP structures in aerospace applications. New specialized high energy CT devices have been laid out for inspection of complete cars before and after crash tests. High speed applications with flash tubes permit the 3D measurement of fast process dynamics including car crash visualization. Digital radiography techniques, computed tomography and computed laminography designs are nowadays developed by numerical simulation before hardware construction. New X-ray source concepts based on laser wake field acceleration permit further reduction of spot sizes and minifocus high energy applications.

New approach for X-ray weld inspection of pipeline segments

As pipeline segments are safety-relevant parts with demanding international quality standards it is required to perform a comprehensive X-ray inspection of the welding lines after production. This paper will present leading quality standards like ISO-17636-2 and API 5L and will highlight their practical relevance.

A main focus will be the different quality metrics like spatial resolution (SRb), Signal-to-Noise Ratio (SNR), Contrast Sensitivity (CS) and long-term stability evaluation of Digital Detector Arrays (DDA). Furthermore, it will introduce different set-ups to inspect the welding lines created by different techniques (spiral, longitudinal and circumferential). An outlook will present automation techniques to increase throughput, while ensuring highest process safety. It will provide responsible NDT managers with comprehensive tools to calculate Return on Investment (ROI) of finances aspects in Digital Radiography (DR) and to ensure a smooth transition from traditional film techniques.

Comprehensive Monte-Carlo Simulator for Industrial Gamma Ray Radiography in Non-destructive Testing

In the present paper, a monte-carlo simulator for conventional industrial radiography has been introduced. Acquiring the acceptable precise simulated radiographic image respecting of the object geometrical shape, atomic number, density etc. was the main purpose of this study. Although there are some commercial softwares available for this purpose, all of these softwares have been using analytical or finite element methods for simulating the radiographic images. They don’t influence the complicated random behavior of Gamma ray photons due to not affecting the photons’ cross-sections with different matters in different energies. Co-60, Se-70, Cs-137 and Ir-192 are the most usable radioisotopes which simulated in our simulator. We have utilized a monte-carlo code MCNPX2.7e for transporting Gamma ray photons. Our comprehensive monte-carlo simulator can get radioisotopes’ energy distribution and then pass photons through geometrical shapes. Results showed our technique for simulating radiographic testing can strongly be accurate even for exact simulations. Unlike the other models, our monte-carlo modeling observations showed it is able to measure and able to map the scattered photons as well as primary ones. It is very crucial if we want to investigate the effective parameters on our radiographic testing in order to optimize them before implementing experimental set-up.