STL File Generation with Data Reduction by the Delaunay Triangulation Method in Reverse Engineering

For the current generation of rapid-prototyping models, laser scanners are currently being used more frequently due to rapid first measuring speed and high precision. Direct generation of an STL file from the digitised points has a great of advantage in that it can reduce time and error during the modelling process. A reduction in the number of point data is important while generating the STL file directly from the measured point data and maintaining precision. A new approach is developed in this paper to generate an STL file directly from point clouds by indicating a tolerance e to maintain precision. The STL file can be generated directly from scattered points using a new algorithm that reduces and triangulates digitised point data based on triangulation of 3D parametric surfaces. Two experimental examples are presented to demonstrate the effectiveness and efficiency of the proposed algorithm.

Rapid prototyping processes produce parts layer by layer directly from CAD models. An efficient method is required to slice the geometric model of a part into layers. Several slicing methods are introduced in this paper: slicing from STL files; tolerate-errors slicing; adaptive slicing; direct slicing; adaptive and direct slicing. PowerSHAPE is a powerful package for building models, and it provided macro language and picture files for its secondary development work. To meet rapid prototyping slicing demands, the author proposes a direct slicing approach based on PowerSHAPE models. In this method, lines, arcs and Bezier curves are used to describe the section contours. This approach can be used in stereolithography, selective laser sintering, fused deposition modelling, and other rapid prototyping processes, e.g. laminated object manufacturing. It may be the future solution to existing slicing problems.

A model for interfacing geometric modeling data with rapid prototyping systems

The integration of reverse engineering (RE) and 3D scanning technologies has enhanced efforts to digitally preserve cultural heritage artifacts. However, ensuring dimensional accuracy during data processing, particularly in STL file generation, remains a critical challenge. This study investigates the digital reproduction of the Sundang Raja Muhamad, a 500-year-old Melaka weapon of significant historical value, by comparing the dimensional accuracy of two 3D scanning systems (Rexscan CS2+ and T-Track/T-Scan) and two STL workflows (Direct and Indirect). Direct STL files were produced with minimal manipulation, whereas Indirect STL files underwent additional refinement through surface reconstruction and mesh editing. Dimensional fidelity was evaluated using CAD-to-CAD and CAD-to-Part analyses at five key diameter points on the hilt. Results show that Direct STL files consistently preserved higher geometric accuracy, while Indirect STL files exhibited larger deviations due to extended mesh reconstruction, particularly in regions with limited scan accessibility. The most notable error occurred at Point E, where deviation exceeded the study’s ±0.30 mm tolerance threshold. In terms of scanning performance, Rexscan CS2 + achieved slightly superior overall dimensional accuracy (85.74%) compared to T-Track/T-Scan (84.84%), especially in areas with fine surface details. However, both systems demonstrated limitations when scanning recessed or obstructed features. The findings highlight the importance of selecting appropriate scanning technology and STL processing methods for heritage preservation. Direct STL workflows and tructured-light scanning provide more reliable geometric fidelity, whereas Indirect workflows are better suited for visual enhancement rather than precision applications.

The Delaunay triangulation (DT) method for multivariate calibration is a topological multivariate calibration method. In this paper, we present methods for the definition of the calibration domain. Outliers in the calibration set must be found and deleted and clusters detected. When clusters are found, it may be advantageous to make separate local models. Two methods are proposed. The first, called the DT calibration domain algorithm, is based on finding a kernel of samples that is then extended according to local rules. An alternative is to first eliminate gross outliers and then divide the data set in clusters, if such clusters exist, with Dbscan, a density‐based clustering method. The cluster(s) is (are) then used as kernels(s) and extended with the same rules as the DT calibration domain algorithm to develop DT models for each cluster. The two methods and some of the difficulties that can be encountered with them are demonstrated with three simulated data sets and tested with three real NIR d...

During the last four decades laser beam machining has been used as a powerful tool in rapid prototyping. Nd:YAG lasers are most widely used in machining of engineering materials, especially silicon for Micro-Electro-Mechanical-Systems (MEMS). Apart from laser micro-welding or laser micro-drilling, laser micro-cutting is one of the most important processes in rapid prototyping. In recent years the researchers have focused on the parameters of the laser beam, such as the pulse duration, the wavelength, the laser power, and the repetition rate. All these parameters depend on the laser system and can be varied in a wide range. The basic parameters - the focus position, the pulse overlap, the track overlap, the number of tracks, and the influence of wobbling - were mostly neglected, although their effect on laser micro-cutting is essential and independent of the above mentioned parameters of the laser system. This research work investigated laser micro-cutting holes in silicon wafers with a nanosecond Nd:YAG UV laser and determines for each parameter the number of scans, the required manufacturing time, the diameter on the laser beam output side as well as on the input side, and the corresponding flank angle.

In the dynamic and customer-centric business landscape of the 21st century, organizations are increasingly turning to innovative methodologies to drive meaningful and effective solutions to complex problems. This paper explores the integration of LEGO® SERIOUS PLAY® into design thinking sessions as a method for rapid prototyping with a focus on customer-centricity. By combining the principles of design thinking, rapid prototyping, and LEGO® SERIOUS PLAY® methodology, this study aims to investigate how the construction of these scenes, coupled with storytelling and pitch development, can facilitate the exploration of customer pain points and gains to inform solution ideation and iteration. A detailed case study is presented to illustrate the application of this approach, highlighting the process from problem identification to prototype creation and feedback gathering. Through analysis and reflection, this paper identifies key insights into the effectiveness of using LEGO® SERIOUS PLAY® for rapid prototyping within design thinking sessions, as well as challenges and opportunities for future research and practice. Ultimately, this study underscores the potential of prototyping as a valuable tool for fostering creativity, collaboration, and customer-centric innovation in organizations seeking to drive positive change and deliver impactful solutions. We are exploring how using this approach can help organizations unlock the full potential of their teams, drive breakthrough innovation and create lasting impact in an ever-changing world. OBJECTIVES: Exploration of LEGO® SERIOUS PLAY® within the design thinking process for rapid prototyping in the context of envisioning the future of cities. Specifically, the paper aims to demonstrate how these methodologies can foster creativity, collaboration, and customer-centric innovation, particularly in uncertain and complex environments as categorized by the Stacey Matrix. METHODS: This study employs a series of 20 design thinking sessions using LEGO® Serious Play to engage diverse stakeholders in imagining the city of 2030. The methods include defining the initial problem statement, conducting empathy exercises to understand user needs and utilizing LEGO® SERIOUS PLAY® for constructing scenes that highlight customer pain points and gains. Developing and presenting pitches and stories based on these LEGO® models and reframing and recreating prototypes based on cross-pollination of ideas. RESULTS: Participants quickly generated rapid prototypes that visually and tangibly represented their ideas. Several specific problems were identified, each accompanied by customer-centric solutions. The use of LEGO® SERIOUS PLAY® facilitated deeper engagement, creativity, and collaboration among participants. Storytelling and pitching helped effectively communicate the envisioned future scenarios and solutions. Feedback from stakeholders provided valuable insights that guided iterative refinement of the prototypes. CONCLUSION: Design thinking, when combined with LEGO® SERIOUS PLAY®, proves to be an effective methodology for rapid prototyping and innovation in complex and uncertain environments. The approach encourages a customer-centric mindset, ensuring that solutions are relevant and impactful. The iterative process of prototyping and feedback leads to continuous improvement and refinement of ideas. LEGO® SERIOUS PLAY® enhances creativity and collaboration, making it a valuable tool in the design thinking toolkit. This integrated methodology can help organizations navigate and transform ambiguity into actionable opportunities for innovation, particularly in the context of future urban planning and development.

PurposeThis paper aims to present a proposal for the restoration of a silver crown by means of fitting pieces produced by the process of 3D modelling and rapid prototyping. It also analyses the benefits of this procedure in restoration of objects weakened by corrosive processes.Design/methodology/approachElemental chemical analysis was carried out in the alloy used in the manufacture of the crown and the constructive and corrosive processes present were studied. Three fitting pieces were modelled and prototyped in wax casting by the stereolithography apparatus system aiming to restore the part and protect the original metal against impacts and external tensions which could speed up some deterioration processes.FindingsThe procedure presented in this paper has shown that formal and dimensional accuracy, only achieved by means of 3D technologies, made the restoration and mechanical stability of the crown possible without the use of adhesives or welding.Originality/valueThe proposed procedure is a new restoration alternative which causes minimal impact to the object and abides by the main standards for modern conservation. It is made with metal which is compatible with the original piece, retractable and easily identifiable.

PurposeTo discuss integration of the rapid prototyping environmental aspects with the primary focus on electrical energy consumption.Design/methodology/approachVarious manufacturing parameters have been tested on three rapid prototyping systems: Thermojet (3DS), FDM 3000 (Stratasys) and EOSINT M250 Xtended (EOS). The objective is to select sets of parameters for reduction of electrical energy consumption. For this, a part is manufactured in several orientations and positions in the chamber of these RP systems. For each test, the electrical power is noted. Finally, certain rules are proposed to minimize this electrical energy consumption during a job.FindingsIt is important to minimize the manufacturing time but there is no general rule for optimization of electrical energy consumption. Each RP system must be tested with energy consumption considerations under the spotlight.Research limitations/implicationsThe work is only based on rapid prototyping processes. The objective is to take into consideration the complete life‐cycle of a rapid prototyped part: manufacturing of raw material as far as reprocessing of waste.Practical implicationsReduction of electrical energy consumption to complete a job.Originality/valueCurrently, environmental aspects are not well studied in rapid prototyping.

Octree reinforced thin-shell rapid prototyping

Some of the Rapid Prototyping (RP) processes have seen enormous improvements in the recent past and are racing towards Rapid Manufacturing (RM), the ability to produce end use parts directly from CAD files. While this sounds quite exciting, considering the time-to-market constraints constantly faced by manufacturing engineers, the key question to be answered is whether the processes are truly capable of achieving the required quality standards. This paper addresses this question considering the mechanisms of material consolidation in a couple of RP processes that are currently considered sure candidates for RM. The conclusion is that RM is a possibility, but depends on the outcomes of research and development activities yet to be undertaken in many directions.

In a typical arc spray prototyping process, two metal wires was melt by electric arc at certain distance and sprayed to the mold surface with high speed compressed air from the jet. To prevent failures such as deformation and cracking, homogeneous temperature field distribution was required for every spray layer. This can be achieved by optimizing the processing parameters using numerical simulating of the temperature distribution. The 3-D temperature simulating technology in the rapid prototyping process using arc spray was introduced. A 3-D model for temperature distribution was established using finite element method. In this model, arc spray rapid prototyping is considered as a process in which every molten drop moves along the path and overlays one another. The movement of the heat source was defined by a function. The temperature evolution as a function of time and the temperature distribution gradient of the sprayed layer were simulated. A real-time measurement of the temperature field was also conducted using infrared thermal imaging system. Results show that the simulating fits well with the experimental data.

Prototypes of a design are always needed for the purposes of visualisation and evaluation for manufacturability, functionality, and aesthetic appearance. Since the prototyping process requires a significant amount of cost and time, various rapid prototyping processes have recently been introduced. However, it is usually necessary for a part built up by a rapid prototyping system to be finished by a post-processing process, in which the stair steps on the surfaces, the support structures (if they exist), and the unprocessed material are eliminated. This post-processing is usually done manually and is a time-consuming task. Eliminating the trapped volumes (the volume of the unprocessed material entrapped by the solidified portion) is sometimes impossible in some processes. This study provides a designer with a tool to detect the existence of trapped volumes and to calculate the quantity in a given build-up direction, so that a suitable build-up direction is chosen or the part is built in pieces to avoid the problems caused by the trapped volumes. Since the proposed algorithm can efficiently calculate the amount of the trapped volumes in any build-up direction, it has the potential for such applications as optimising the build-up direction to minimise the trapped volumes.

Establishment of Process Model for Rapid Prototyping Technique (Stereolithography) to Enhance the Part Quality by Taguchi Method

Towards the three-dimensional FE analysis of rapid prototyping tools for sheet metal stamping process