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3D inspection process is getting more and more interest for manufacturing industries as it helps to carefully check the expected quality of the released products. Much more attention is oriented to optical devices able to quickly capture the whole shape of the product providing many useful information on the process variability and the deliverability of the key characteristics linked to the quality of the product/process. Although the optical control of 3D scanners is mature enough, many factors may influence the quality of the scanned data. These factors may be strictly related to internal elements to the acquisition device, such as scanner resolution and accuracy, and external to it, such as proper selection of scanning parameters, ambient lighting and characteristics of the object surface being scanned (e.g. surface colour, glossiness, roughness, shape), as well as the sensor-to-surface relative position. For the 3D laser-based scanners, the most common on the market, it would be of great industrial interest to study some scanning factors mainly affecting the quality of the 3D surface acquisitions and provide users with guidelines in order to correctly set them so to increase the massive usage of these systems in the product inspection activities. In this context, by using a commercial triangulation 3D laser scanner, the effects of some scanning factors that may affect the measurement process were analysed in the present paper. Working on a sheet metal test part, more complex than the ones commonly used in laboratory and documented in the literature, the scanner-to-object relative orientation and the ambient lighting, as well as an internal scanner parameter, were tested. Through a Design of Experiments (DoE) approach, and setting root mean square error (RMSE) as response function, the outcomes of the tests mainly pointed out that the scanner-to-object relative orientation as well as its position within the field of view of the measurement device are the key factors mostly influencing the accuracy of the measurement process

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In this paper, a general methodology to do tolerance analysis of rigid assemblies is proposed. Firstly, tolerance specification sets, according to GD&T or ISO specifications, are translated into variational features by using 4×4 homogenous transformation matrices. In particular, planar and cylindrical features are considered. Then, once all variational features are modeled, assembly constraints among parts are introduced. To solve assembly constraints, an assembly transformation matrix is evaluated. By using point, line, and plane entities and their combinations, kinematic joints are modeled. A numerical procedure is proposed to solve fully and over-constrained assemblies. The best-fit alignment among variational mating features is performed by using optimization algorithms. The proposed method for tolerance analysis of rigid part assemblies allows to simulate different assembly sequences. Finally, in order to show the effectiveness of the proposed methodology, three case studies are described and analyzed

The optimization of production processes has always been one of the cornerstones for manufacturing companies, aimed to increase their productivity, minimizing the related costs. In the Industry 4.0 era, some innovative technologies, perceived as far away until a few years ago, have become reachable by everyone. The massive introduction of these technologies directly in the factories allows interconnecting the resources (machines and humans) and the entire production chain to be kept under control, thanks to the collection and the analyses of real production data, supporting the decision making process. This article aims to propose a methodological framework that, thanks to the use of Industrial Internet of Things-IoT devices, in particular the wearable sensors, and simulation tools, supports the analyses of production line performance parameters, by considering both experimental and numerical data, allowing a continuous monitoring of the line balancing and performance at varying of the production demand. A case study, regarding a manual task of a real manufacturing production line, is presented to demonstrate the applicability and the effectiveness of the proposed procedure.

Within the era of smart factories, concerning the ergonomics related to production processes, the Digital Twin (DT) is the key to set up novel models for monitoring the performance of manual work activities, which are able to provide results in near real time and to support the decision-making process for improving the working conditions. This paper aims to propose a methodological framework that, by implementing a human DT, and supports the monitoring and the decision making regarding the ergonomics performances of manual production lines. A case study, carried out in a laboratory, is presented for demonstrating the applicability and the effectiveness of the proposed framework. The results show how it is possible to identify the operational issues of a manual workstation and how it is possible to propose and test improving solutions.

T he stereolithography process is a rapid prototyping method that produces physical models by selectively solidifying an ultravioletsensitive liquid resin using a laser beam. 1-5 It represents a relatively new technology in the diagnostic area. The status of this new methodology in clinical and surgical medicine is still at the prototype stage. It can be used for surgical simulation to assure predictable results and to diminish operation time. [1][2][3][4][5][6][7] In oral implantology, this technology allows for a precise evaluation of anatomic points such as the size of the maxillary sinus in the upper jaw and the location of the alveolar nerve in the lower jaw, 1-8 and it can be applied to provide information about size, direction, and bone location for accurate positioning of implants. [1][2][3][4][5][6][7][8][9] This study evaluated the possible benefits in planning implant surgery from stereolithographic models and surgical guides relating to clinical guidance methodology. [1][2][3][4][5] The aim of this report is to consider the use of stereolithography in oral implantology and its role in reducing complications in implant dentistry. CASE REPORTA 70-year-old woman with severe mandibular bone atrophy had been presented to our department (Fig. 1). She indicated that her removable complete denture was unstable and caused considerable interference with mastication and speech despite the fact that the restoration had been reworked several times. It was decided to implant 2 fixtures that could assure better stability for a lower prosthesis, so she agreed to implant surgery. To avoid dislocation of the denture, 2 Branemark implants (Nobel Biocare USA, Yorba Linda, CA) 3.75 mm in diameter and 10 mm in length, were used. The implants were located evaluating bone quantity and density by computed tomographic (CT) analysis and its elaboration by SurgiCase software 10 -12 (Fig. 2). Preoperative x-ray showed the real bone jaw atrophy that was identified as a V-VI CawoodHowell Class. To determine the fixation points of the fixtures, a mandibular model and tomographic analysis were used. By means of these examinations, an initial surgical guide was fabricated in which each implant was to be located considering mandibular dimensions and clinical evaluations (gnathologic aspects, relations, and ideal aesthetic teeth positions) (Fig. 3).This article presents the use of stereolithography in oral implantology. Stereolithography is a new technology that can produce physical models by selectively solidifying an ultraviolet-sensitive liquid resin using a laser beam, reproducing the true maxillary and mandibular anatomic dimensions. With these models, it is possible to fabricate surgical guides that can place the implants in vivo in the same places and same directions as those in the planned computer simulation. A 70-year-old woman, in good health, with severe mandibular bone atrophy was rehabilitated with an overdenture supported by 2 Branemark implants. Two different surgical planning methods were considered: 1) the construction...