Search results

The usage of additive manufacturing (AM) technology in industries has reached up to 50 per cent as prototype or end-product. However, for AM products to be directly used as final products, AM product should be produced through advanced quality control process, which has a capability to be able to prove and reach their desire repeatability, reproducibility, reliability and preciseness. Therefore, there is a need to review quality-related research in terms of AM technology and guide AM industry in the future direction of AM development.

This paper overviews research progress regarding the QC in AM technology. The focus of the study is on manufacturing quality issues and needs that are to be developed and optimized, and further suggests ideas and directions toward the quality improvement for future AM technology. This paper is organized as follows. Section 2 starts by conducting a comprehensive review of the literature studies on progress of quality control, issues and challenges regarding quality improvement in seven different AM techniques. Next, Section 3 provides classification of the research findings, and lastly, Section 4 discusses the challenges and future trends.

This paper presents a review on quality control in seven different techniques in AM technology and provides detailed discussions in each quality process stage. Most of the AM techniques have a trend using in-situ sensors and cameras to acquire process data for real-time monitoring and quality analysis. Procedures such as extrusion-based processes (EBP) have further advanced in data analytics and predictive algorithms-based research regarding mechanical properties and optimal printing parameters. Moreover, compared to others, the material jetting progresses technique has advanced in a system integrated with closed-feedback loop, machine vision and image processing to minimize quality issues during printing process.

This paper is limited to reviewing of only seven techniques of AM technology, which includes photopolymer vat processes, material jetting processes, binder jetting processes, extrusion-based processes, powder bed fusion processes, directed energy deposition processes and sheet lamination processes. This paper would impact on the improvement of quality control in AM industries such as industrial, automotive, medical, aerospace and military production.

Additive manufacturing technology, in terms of quality control has yet to be reviewed.

WEAR is one of the major ways by which a material part ceases to be useful, others are corrosion, obsolescence and breakage. It is the consequence of relative motion and in industrial plant and equipment it has always been accepted as inevitable that it should lead to heavy expenditure for maintenance and replacement. Historically, wear is a well established fact, yet our knowledge of the technology is extremely limited. It has become a way of life that we compensate for wear when it no longer can be tolerated, yet need this be so? This article examines the problem, and primarily from the unlubricated point of view, describes the various types of wear and the way material selection or modification can be used to limit wear.

Business Schools and other executive training providers have come under withering attacks since before the global financial crisis for their standardised, non-integrated executive curricula, rigid methods of instruction and weak participant engagement. The crisis has extended this critique. Further criticisms relate to the inability of providers who are schooled in Western paradigms of instruction to manage increasingly multi-cultural, executive workshops. This chapter proposes a play-based approach to executive training. The chapter argues that a play-based approach re-dresses some of the above imbalances and re-positions the interests of entrepreneurial and executive learners. The chapter evaluates the development of the approach to learning by using play-based and experiential-learning simulator called Synergy. Initial arguments are presented with indications and results on why play-based designs can offer a productive response to some of the current criticisms that are levelled at executive and entrepreneurial training provision.

Limited geometric accuracy is one of the major challenges that hinder the wider application of additive manufacturing (AM). This paper aims to predict in-plane shape deviation for online inspection and compensation to prevent error accumulation and improve shape fidelity in AM.

A sequence-to-sequence model with an attention mechanism (Seq2Seq+Attention) is proposed and implemented to predict subsequent layers or the occluded toolpath deviations after the multiresolution alignment. A shape compensation plan can be performed for the large deviation predicted.

The proposed Seq2Seq+Attention model is able to provide consistent prediction accuracy. The compensation plan proposed based on the predicted deviation can significantly improve the printing fidelity for those layers detected with large deviations.

Based on the experiments conducted on the knee joint samples, the proposed method outperforms the other three machine learning methods for both subsequent layer and occluded toolpath deviation prediction.

This work fills a research gap for predicting in-plane deviation not only for subsequent layers but also for occluded paths due to the missing scanning measurements. It is also combined with the multiresolution alignment and change point detection to determine the necessity of a compensation plan with updated G-code.

Quality 4.0 is an emerging research topic concerned with rethinking how quality management needs to be adopted in the digital era. The purpose of this research is to conduct a systematic review on the state of the research in the field of Industry 4.0 impact on improving quality management aspects and how technology can be leveraged to enhance its practices.

A systematic review of the literature published in the last 5 years is conducted. 52 papers were selected, mapped based on the technology they focused on and categorized based on the addressed quality aspects.

The review revealed various areas where quality management can benefit from Industry 4.0 technologies, identified several research gaps and suggested new directions for future research. Firstly, the literature provided some insights about industry 4.0 potential contributions but lacks further detail on the exact applications and solutions through use cases and case studies. Secondly, there has been a focus on the potential benefits provided for quality control while there is a clear scarcity in terms of the other quality management tools and methodologies. Thirdly, there is a lack of studies on economic analysis or detailed impacts on quality costs that justifies the substantial investments needed. Finally, there is a need for including more studies about the mapping and integration of ISO 9001 requirements and Industry 4.0 features.

This is the first attempt to conduct a comprehensive review on the ways industry 4.0 technologies can be leveraged for the field of quality management. Based on this review, several directions for further research in this area are identified.

This paper aims to investigate the complex relationship between emotions, coping approaches and learning in error situations in the workplace. The study also examines the influence of individual error orientation, as well as psychological safety, and team learning behaviour as contextual factors.

To measure emotions, coping and learning from errors in situ, a semi-standardised error diary was administered. Individual and contextual factors were measured by standard questionnaires. Totally, 22 young employees participated in the study and recorded n = 99 error situations in a three-week diary period.

Errors typically provoked negative emotions, particularly in cases of “public” errors. Negative emotions provoked emotion-focused coping. However, there was no direct effect of emotions on learning. Learning seems to depend primarily on the in-depth analysis of the error, no matter whether the original coping intention is aimed at problem-solving, self-protection or emotion regulation. A quick error correction does not necessarily result in learning. Furthermore, plausible influences of individual and contextual factors were found, but must be interpreted cautiously.

The small sample size, particularly in person-level analyses, is a major shortcoming of the study.

To overcome shortcomings of common retrospective self-reports such as interviews or questionnaires, this study uses the diary method as an innovative approach to investigate processes in situ.

The importance of Carbon dioxide (CO₂) gas detection as a greenhouse and exhale breathe gas is an undeniable issue. This study aims to propose a new miniaturized, low cost and portable no dispersive infrared (NDIR) system for detecting CO₂ gas.

Poly(methyl methacrylate) (PMMA)-based channels with Au coating because of its high reflection properties in IR region were used in this work. The optical windows were fabricated using PDMS polymer which is cost effective and novel in comparison to other conventional methods. The effects of channel dimensions, lengths and entrance angle of light on optical path length and losses were analyzed with four types of channel using both simulation and experimental tests.

The simulation results indicate that the 0 degree light entrance angle is the most efficient angle among different investigated conditions. The experimental data are in agreement with the simulation results regarding the loss and optical path length in different types of channel. The experimental tests were performed for the 0.5% up to 20% of CO₂ concentration under constant temperature and humidity condition. The results show that the device with 5  and 2 cm channels length were saturated in 4% and 8% concentration of CO₂ gas, respectively. Response and recovery times were depending on gas concentration and channels specifications that in average found to be 10 S and 14 S, respectively, for the largest size channel. Moreover, the environment humidity effect on detection system performance was investigated which had no considerable influence. Also, the saturation fraction absorbance value for devices with various dimensions were 0.62 and 0.8, respectively.

According to the performed curve fitting for practical situation and selected CO₂ concentration range for experimental tests, the device is useful for medical and environmental applications.

PMMA with Au deposition layer was used as a basic material for this NDIR system. Besides, a novel PDMS optical window helps to have a low cost device. The effects of channel dimensions, lengths and entrance angle of light on optical path length and losses were analyzed using both simulation and experimental tests. Using narrowband optical filter (100 nm bandwidth) helps to have a system with good CO₂ selectivity. In addition, experimental tests with different channel dimensions and lengths covered a considerable range of CO₂ concentration useful for medical and environmental applications. Finally, curve fitting was adopted for a modified Beer–Lambert law as a practical situation.

Path planning is an important part of three-dimensional (3D) printing data processing technology. This study aims to propose a new path planning method based on a discontinuous grid partition algorithm of point cloud for in situ printing.

Three types of parameters (i.e. structural, process and path interruption parameters) were designed to establish the algorithm model with the path error and the computation amount as the dependent variables. The path error (i.e. boundary error and internal error) was further studied and the influence of each parameter on the path point density was analyzed quantitatively. The feasibility of this method was verified by skin in situ printing experiments.

Path point density was positively correlated with Grid_size and negatively related to other parameters. Point_space, Sparsity and Line_space had greater influence on path point density than Indentation and Grid_size. In skin in situ printing experiment, two layers of orthogonal printing path were generated, and the material was printed accurately in the defect, which proved the feasibility of this method.

This study proposed a new path planning method that converted 3D point cloud data to a printing path directly, providing a new path planning solution for in situ printing. The discontinuous grid partition algorithm achieved controllability of the path planning accuracy and computation amount that could be applied to different processes.

The analysis of ancient buildings presents professionals with important challenges, so it is necessary to have a rational methodology of analysis of these constructions. From the point of view of the technology of structures it is imperative to know the mechanical characteristics of the structural elements involved, as well as the existing stress levels. Currently the tendency is to obtain such knowledge in a non‐destructive way, producing minimal damage. The purpose of this paper is to provide a vision of some of the minor‐destructive techniques (MDT) applied to the diagnosis of historical rubble stone masonry structures.

The paper focuses attention on the employment of techniques based on mechanical stress aspects: flat jack, hole‐drilling and dilatometer, conducted on rubble stone masonry structures. Several computational models were made of parts of the building. These models were used to obtain experimental data (modulus of elasticity and Poisson's ratio). The accuracy of the models was contrasted through the comparison with compression stress levels obtained experimentally.

The paper provides a brief description of these MDT, and exposes the flat jack tests results obtained on several historical masonry walls in the Major Seminary of Comillas (Spain): Compression stress levels, modulus of elasticity and Poisson's ratio of several masonries of this building.

These techniques improve the computational models of constructions, because they can obtain a better knowledge of their mechanical properties, from experimental ways, and the calibration of models through experimental data.

This paper describes one of the first applications of these techniques in Spain.

This paper is a continuation of “No‐fines concrete in the UK social housing stock: 50 years on” published in Issue 4 of Volume 29 of this journal. It identifies the thermal performance of existing, un‐refurbished no‐fines concrete (NFC) walls; as about 33,000 NFC homes exist in Scotland. A majority of these properties are owned by social housing providers (SHPs) and are being upgraded to current building standards. Literature identifies the thermal performance (U‐value) of NFC walls ranging from 1.1 W/m²K to 2.0 W/m²K depending on the build‐up of the structure. The homes are classified as “hard to treat” and, as a result, the occupants experience “fuel poverty”. SHPs currently adopt a range of measures to refurbish NFC properties and adopt a broad brush approach, refurbishing a range of non‐traditional (NT) constructed dwellings under similar refurbishment packages. The purpose of this paper is to call for a re‐think in terms of such refurbishment approaches when seeking to improve the thermal performance of NFC properties.

Various cores were extracted from NFC homes in the West of Scotland to explore the heterogeneity of NFC construction. To measure the thermal performance of existing NFC homes, in situ u‐value calculations were undertaken through case studies and fieldwork.

The findings of this research highlight the heterogeneity of NFC construction. The paper discusses the different approaches adopted by SHPs and identifies the variations between individual NFC elements resulting from workmanship and build issues.

The findings expose the heterogeneity of individual NFC elements and further suggest that any decision to adopt a refurbishment approach must be based on a detailed consideration of the existing characteristics of the property including location and orientation of the property.

This paper is the first to discuss the in situ u‐values of NFC properties in the last 20 years. It will be of interest to SHPs planning to refurbish such properties.