Tobias Kolb, Reza Elahi, Jan Seeger, Mathews Soris, Christian Scheitler, Oliver Hentschel, Jan Tremel and Michael Schmidt
The purpose of this paper is to analyse the signal dependency of the camera-based coaxial monitoring system QMMeltpool 3D (Concept Laser GmbH, Lichtenfels, Germany) for laser…
Abstract
Purpose
The purpose of this paper is to analyse the signal dependency of the camera-based coaxial monitoring system QMMeltpool 3D (Concept Laser GmbH, Lichtenfels, Germany) for laser powder bed fusion (LPBF) under the variation of process parameters, position, direction and layer thickness to determine the capability of the system. Because such and similar monitoring systems are designed and presented for quality assurance in series production, it is important to present the dominant signal influences and limitations.
Design/methodology/approach
Hardware of the commercially available coaxial monitoring QMMeltpool 3D is used to investigate the thermal emission of the interaction zone during LPBF. The raw images of the camera are analysed by means of image processing to bypass the software of QMMeltpool 3D and to gain a high level of signal understanding. Laser power, scan speed, laser spot diameter and powder layer thickness were varied for single-melt tracks to determine the influence of a parameter variation on the measured sensory signals. The effects of the scan direction and position were also analysed in detail. The influence of surface roughness on the detected sensory signals was simulated by a machined substrate plate.
Findings
Parameter variations are confirmed to be detectable. Because of strong directional and positional dependencies of the melt-pool monitoring signal a calibration algorithm is necessary. A decreasing signal is detected for increasing layer thickness. Surface roughness is identified as a dominating factor with major influence on the melt-pool monitoring signal exceeding other process flaws.
Research limitations/implications
This work was performed with the hardware of a commercially available QMMeltpool 3D system of an LPBF machine M2 of the company Concept Laser GmbH. The results are relevant for all melt-pool monitoring research activities connected to LPBF, as well as for end users and serial production.
Originality/value
Surface roughness has not yet been revealed as being one of the most important origins for signal deviations in coaxial melt-pool monitoring. To the best of the authors’ knowledge, the direct comparison of influences because of parameters and environment has not been published to this extent. The detection, evaluation and remelting of surface roughness constitute a plausible workflow for closed-loop control in LPBF.
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Previous research has highlighted a contradiction in regard to environmental reporting in South Africa. Managers, who can influence decisions regarding disclosure, express the…
Abstract
Previous research has highlighted a contradiction in regard to environmental reporting in South Africa. Managers, who can influence decisions regarding disclosure, express the view that more environmental reporting is needed, yet very little such reporting is done. A questionnaire was sent to every company listed on the Johannesburg Stock Exchange (JSE) with the request that the financial director should complete it. The questionnaire set out to establish whether managers are still as positive about environmental reporting as reported in previous research findings and, furthermore, to determine the reasons for the dearth of environmental reporting. Managers are still as positive as before about environmental reporting. The reasons for not reporting range from the contention that data is not available, that there are no legal requirements and that there is no demand for the data to the contention that it is not applicable to the particular industry and that costs exceed benefits. Most respondents do not regard the fear of liability to be a very important reason for non‐disclosure. The most important reason for non‐disclosure is that there is no legal requirement in respect of disclosure. This reason, together with the positive attitude of directors towards environmental reporting in general and towards reporting on a compulsory basis in particular, makes a strong case for the introduction of legislation in this regard. The introduction of legislation could be achieved by amending the Fourth Schedule of the Companies’ Act or the introduction by The South African Institute of Chartered Accountants (SAICA) of a statement of Generally Accepted Accounting Practice (GAAP) on environmental disclosure.
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THE luncheon given by the Lord Mayor, Sir Ralph Perring, to more than 700 guests at Guildhall on November 14, officially launched the country on National Productivity Year. Apart…
Abstract
THE luncheon given by the Lord Mayor, Sir Ralph Perring, to more than 700 guests at Guildhall on November 14, officially launched the country on National Productivity Year. Apart from representatives of the 120 local committees these were people from trade and employers' associations, trades unions, professional bodies and research organisations. It was, in effect, a token mobilisation of Britain's industrial might, because behind it stands a large army devoted to the task of increasing the country's output.
In the novel, The Member of the Wedding, Carson McCullers probes the American malaise through the longings of a young adolescent girl. Twelve‐year‐old Frankie no longer sees the…
Abstract
In the novel, The Member of the Wedding, Carson McCullers probes the American malaise through the longings of a young adolescent girl. Twelve‐year‐old Frankie no longer sees the world as round and inviting as a school globe. No, the world is huge and cracked and turning a thousand miles an hour. Indeed, the world seems separate from herself. In the midst of chaos, Frankie sees her brother's upcoming wedding as a chance to feel connected, to feel that she matters. The story focuses on Frankie's efforts to be a “member of the wedding,” as she recognizes, “they are the we of me.”
Bruce J. Eberhardt, Abdullah Pooyan and Steven B. Moser
This study investigated possible moderating effects on the relationship between job satisfaction and nurses' intention to quit. Using data collected from 327 registered nurses in…
Abstract
This study investigated possible moderating effects on the relationship between job satisfaction and nurses' intention to quit. Using data collected from 327 registered nurses in three large private hospitals, moderator regression analysis revealed significant main and moderating effects for employee age. When the effects of education, employment status, and marital status were controlled, the main and moderating effects of age on the relationship between job satisfaction and nurses' intention to quit remained significant. Alternative explanations of the results are discussed, along with implications of the findings for nursing turnover research.
Few librarians think of U.S. documents as a source for professional reading, growth, and information, yet several agencies of the government are involved with library programs…
Abstract
Few librarians think of U.S. documents as a source for professional reading, growth, and information, yet several agencies of the government are involved with library programs, services, and research. This bibliography is a compilation of some of the most recent documents about libraries published by these agencies. It is an eclectic group, ranging from scholarly research studies to descriptions of model programs. Most of these studies are known only to a small segment of the library profession and have not received wide distribution in the field. The quality of the documents is quite good, particularly the research reports being done out of the Department of Education's Office of Educational Research and Improvement (OERI) Library Programs Office. Much of the information contained in the surveys and research reports is not available in any other form.
‘WORK STUDY specialists of Europe—from both the Six and the Seven— are getting together in London this year regardless of what happens to other meetings,’ said Mr. R. M. Currie…
Abstract
‘WORK STUDY specialists of Europe—from both the Six and the Seven— are getting together in London this year regardless of what happens to other meetings,’ said Mr. R. M. Currie, C.B.E., President of the European Work Study Federation, in a statement on the forthcoming Congress of the Federation which is to take place at Church House, Westminster, from May 20 to 23.
Looks at the 2000 Employment Research Unit Annual Conference held at the University of Cardiff in Wales on 6/7 September 2000. Spotlights the 76 or so presentations within and…
Abstract
Looks at the 2000 Employment Research Unit Annual Conference held at the University of Cardiff in Wales on 6/7 September 2000. Spotlights the 76 or so presentations within and shows that these are in many, differing, areas across management research from: retail finance; precarious jobs and decisions; methodological lessons from feminism; call centre experience and disability discrimination. These and all points east and west are covered and laid out in a simple, abstract style, including, where applicable, references, endnotes and bibliography in an easy‐to‐follow manner. Summarizes each paper and also gives conclusions where needed, in a comfortable modern format.
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Before we start looking for information on a specific company, it would be logical to first find our what type of company it is. Broadly speaking, companies fall into two major…
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Before we start looking for information on a specific company, it would be logical to first find our what type of company it is. Broadly speaking, companies fall into two major categories, namely, private and public. A private company could in turn be a sole proprietorship, a partnership or an incorporated enterprise. A public company, on the other hand could be a parent company or a subsidiary, affiliate or a division of the parent. In addition, it is possible for either type of company to be a franchise or be of foreign origin. For our purposes, we may define a public company to be a company whose stock is listed on a national or a regional stock exchange and any company that is not public is a private company. Although the process of business formation is beyond the scope of this review, it would facilitate one's research if one is familiar with sources that provide information in this area. Besides, there is a constant demand in business libraries for information on how to set up businesses.
THE ordinary work study practitioner will naturally ask what difference a European Work Study Federation will make to him. If it is to have his whole‐hearted support he will need…
Abstract
THE ordinary work study practitioner will naturally ask what difference a European Work Study Federation will make to him. If it is to have his whole‐hearted support he will need to be satisfied that it will bring him advantages he would not obtain otherwise. It is too early to give precise answers to such questions. There are, however, some reasonable deductions that can be made.