The digitalization of manufacturing fuels the application of sophisticated virtual product models, which are referred to as digital twins, throughout all stages of product realization. Particularly, ...more realistic virtual models of manufactured products are essential to bridge the gap between design and manufacturing and to mirror the real and virtual worlds. In this paper, we propose a comprehensive reference model based on the concept of Skin Model Shapes, which serves as a digital twin of the physical product in design and manufacturing. In this regard, model conceptualization, representation, and implementation as well as applications along the product life-cycle are addressed.
Design for additive manufacturing has gained extensive research attention in recent years, whereas tolerancing issues aiming at controlling geometric variations remain a major bottleneck in achieving ...predictive models and realistic simulations. In this paper, a prescriptive deviation modelling method coupled with machine learning techniques is proposed to address the modelling of shape deviations in additive manufacturing. The in-plane geometric deviations are mapped into an established deviation space and Bayesian inference is used to estimate geometric deviations patterns by statistical learning from multiple shapes data. The effectiveness of the proposed approach is demonstrated and discussed through illustrative case studies.
Variability is unavoidable in the realization of products. While design must specify ideal geometry, it shall also describe limits of variability (tolerances) that must be met in order to maintain ...proper product function. Although tolerancing is a mature field, new manufacturing processes and design methodologies are creating new avenues of research, and modelling standards must also evolve to support these processes. In addition, the study of uncertainty has produced widely-accepted methods of quantifying variability, and modern tolerancing tools should support these methods. The challenges introduced by new processes and design methodologies continue to make tolerancing research a fertile and productive area.
Geometric dimensioning & tolerancing (GD&T) is an important step in product design and manufacturing. A good GD&T design is vital to ensure the quality and manufacturability of a product. So far, a ...datum-based model has been utilized to expedite the GD&T design. Even though the speed has been increased, the quality of the GD&T design is still largely dependent on designer's previous experience, such as the experience in part design, machining, and measuring. Without more detailed guidance, engineering novices are likely to make a variety of common mistakes while they use the datum-based model. To address this issue, the authors collected and analyzed the typical errors from the previous GD&T designs and set up a specification that instructs the GD&T designer what should be and should not be done in each layer of the datum-based model. This rule-based GD&T design specification was piloted in 2021. The result shows that the quality of the GD&T design has been considerably improved. The ruled-based specification introduced in this paper does not only help produce high-quality designs, which are required by front-end research, such as autonomous machining, but also signifies a step forward in achieving the full automation of the GD&T process.
Part representation in additive manufacturing (AM) is dominated by the stereolithography (STL) file format as a universal mode for communicating and transferring part geometry from one system to ...another. However, when the CAD model is converted to the triangle mesh constituting the STL file the topology is no longer explicitly defined hence the design intent is lost together with any tolerancing information. Computer aided tolerancing of actual part geometry is hindered by the sparse information about the nominal geometry directly available in STL data, therefore the feature information is often assumed or recreated through reverse engineering methods. This paper investigates how nominal geometry can be deduced from STL data to support quality control by the identification of geometric elements from a triangle mesh. We further discuss how vectorial tolerancing can extend the scope of feature recognition to tolerancing and quality assessment. A method for automatic extraction and tolerancing of features from STL files is described and an application example is provided. The outlined method enables the automation of tolerancing activities and facilitates the integration of STL files into the digital pipeline of modern manufacturing systems.
A key focus of the CIRP CAT 2020 is the role of standardization in GPS specification, and the constraints and opportunities provided by standards throughout the design lifecycle, including in the ...verification of products. This focus is supported by two Keynote presentations from the chairmen of the ASME and ISO committees that develop standards for the specifications of geometric tolerances. The CIRP CAT conferences provide an opportunity for researchers and practitioners to exchange new ideas and discuss the implications of new and evolving research in the areas of geometrical tolerancing, assembly analysis, modeling of manufacturing processes, and standardization.
Almost all current dimensioning and tolerancing and GPS methods have been created to define the allowable geometric variation of nominally smooth and continuous surfaces. However, there are many ...industrial applications where surfaces are not nominally smooth and continuous. Examples include textured surfaces used in automotive interiors (such as leather, faux leather, and fabric), and theoretical surfaces that are collections of geometric elements, such as mesh and rigidized metal surfaces, which can be visualized as a set of discrete tangent points. This paper will propose tools and methods to identify and define highly-interrupted features and tools and methods to control the allowable variation of highly-interrupted features in a product definition data set.
In tolerancing activities focusing on the allocation of geometrical tolerances, many critical issues originate from the non-optimal assignment of responsibilities among the organization units ...involved. This paper aims to depict relations between different tolerancing activities and relevant specifications, assigning them to the proper actor and, therefore, expanding the ISO 8015:2011 “responsibility principle”. A classification among tolerancing activities, specifications, and media is proposed; a horizontal hierarchical framework among functional, manufacturing, and verification specifications and a vertical hierarchical framework along the supply chain are discussed. Examples of both hierarchical structures are presented.
In high-tech production, companies often deal with the manufacturing of assemblies with quality requirements close to the technological limits. Selective and adaptive production systems are means to ...cope with this challenge. In this context new measurement technologies and IT-systems offer the opportunity to generate and use real-time quality data along the process chain and to control the production system adaptively. In this article, a holistic matching approach to optimize the performance of selective and adaptive assembly systems is presented and its industrial application within an automotive electric drive assembly is demonstrated.
Many activities in design and manufacturing rely on realistic product representations considering geometrical deviations to assess their effects on the product function and quality. Though several ...approaches for tolerance analysis have been developed, they imply several shortcomings, such as the lack of form deviations consideration and the high manual modelling effort. In this paper, a novel shape-agnostic approach supported by generative adversarial networks is developed for the automated generation of part representatives with geometrical deviations. A workflow for generating these variational part representatives is highlighted and tolerance analysis case studies demonstrate the effectiveness of the proposed approach.
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