RAPID prototyping, COMPUTER-aided design, SPLINES, RAPID tooling, and TESSELLATIONS (Mathematics)
Purpose – This paper aims to propose a global adaptive direct slicing technique of Non-Uniform Rational B-Spline (NURBS)-based sculptured surface for rapid prototyping where the NURBS representation is directly extracted from the computer-aided design (CAD) model. The imported NURBS surface is directly sliced to avoid inaccuracies due to tessellation methods used in common practice. The major objective is to globally optimize texture error function based on the available range of layer thicknesses of the utilized rapid prototyping machine. The total texture error is computed with the defined error function to verify slicing efficiency of this global adaptive slicing algorithm and to find the optimum number of slices. A variety of experiments are conducted to study the accuracy of the developed procedure, and the results are compared with previously developed algorithms. Design/methodology/approach – This paper proposes a new adaptive algorithm which globally optimizes a texture error function produced by staircase effect for a user-defined number of layers. The adaptive slicing algorithm dynamically calculates optimized slicing thicknesses based on the rapid prototyping machine’s specifications to minimize the texture error function. This paper also compares the results of implementing the developed methodology with the results of previously developed algorithms and presents cost-effective optimum slicing layer thicknesses. Findings – A new methodology for global adaptive direct slicing algorithm of CAD models, based on a texture error function for the final product and the possible layer thicknesses in rapid prototyping, has been developed and implemented. Comparing the results of implementation with the common practice for several case studies shows that the proposed approach has greater slicing efficiency. Typically, by utilizing this approach, the number of prototyping layers can be reduced by 20-50 per cent compared to the slicing with other algorithms, while maintaining or improving the accuracy of the final manufactured surfaces. Therefore, the developed slicing method provides a better solution to trade-off between the rapid prototyping time and the rapid prototyping accuracy. For the many advantages of global direct slicing, it can be seen as the future solution to the slicing process in rapid prototyping systems. Originality/value – This paper presents an innovative approach in direct global adaptive slicing of the additive manufacturing parts. The novel definition of an error function which comprehensively addresses the resulting manufactured surface quality of the entire product allows presenting an objective function to solve and to find the optimum selection of all the layer thicknesses during the slicing process. [ABSTRACT FROM AUTHOR]
ELECTROSPINNING, RAPID prototyping, FABRICATION (Manufacturing), VIBRATION (Mechanics), and PROTOTYPES
Purpose -- This paper aims to present the development of an electrospinning-based rapid prototyping (ESRP) technique for the fabrication of patterned scaffolds from fine fiber. Design/methodology/approach -- This ESRP technique unifies rapid prototyping (RP) and electrospinning to obtain the ability of RP to create a controllable pattern and of electrospinning to create a continuous fine fiber. The technique follows RP process of fused deposition modeling, but instead of using extrusion process for fiber creation, electrospinning is applied to generate a continuous fiber from a liquid solution. A machine prototype has been constructed and used in the experiments to evaluate the technique. Findings -- Three different lay-down patterns: 0°/90°, 45°/135° and 45° twists were used in the experiments. According to the experimental results, stacks of patterned layers could be created with the ESRP technique, and the fabrication process was repeatable and reproducible. However, the existing machine vibration influenced the fiber size and the ability to control straightness and gap size. Also, incomplete solidification of the fibers prior to being deposited obstructed the control of layer thickness. Improvement on vibration suppression and fiber solidification will strengthen the capability of this ESRP technique. Research limitations/implications -- This research is currently limited to the introduction of the ESRP technique, to the development of the machine prototype, to the demonstration of its capability and to the evaluation of the structural properties of the fabricated patterned scaffolds. Further studies are required for better control of the patterned scaffolds and for investigation of mechanical and biological properties. Originality/value -- This unification of the two processes allows not only the fabrication of controllable patterned scaffolds but also the fabrication of both woven and non-woven layers of fibers to be done on one machine. [ABSTRACT FROM AUTHOR]
Layered Manufacturing (LM) which is the core of Rapid Prototyping (RP) the part is generating using layer-by-layer addition of the material. Where slicing of the Computer-Aided Design (CAD) models on a part to be produced is one of the important steps. Direct slicing a three-dimensional (3D) graphic model into layers of two-dimensional (2D) contour plots is an essential step for all rapid prototyping (RP) machines. This paper establishes a base surface parameterization using direct slicing strategy for based on a vertical sectional design technique using different layers thickness at 3D surface and study the effect of slice thickness on the final 3D model accuracy. The proposed method directly extracting 3D to vertical sectional contours from mathematical definition of parametric surface and converting to (2D) layers, the final surface achieved by manufacturing layers using Computer Numerical Control (CNC) laser cutting machine. A measuring method has been proposed and implemented to measure the accuracy of the final 3D surface. statistical method of error assessment and similarity factor have been implemented in this work to show the efficiency of the proposed work and comparing between original CAD models and prototyping models. The results of similarity factor show that, (84.317%) for 2.5 mm Bezier model, (72.492%) for 4mm Bezier model, (61.012%) for 8mm Bezier model. [ABSTRACT FROM AUTHOR]
This paper discusses the informational requirements of rapid prototyping and layered manufacturing (RPLM). The study is motivated by the recent decision to embark on the development of a new Application Protocol for the international standard ISO 10303, specifically to handle layered manufacturing information.The most common industrial use of RPLM today is for rapid prototyping, but a wider view of it as a flexible fabrication technology is taken here, to allow for future developments. Its use in building functional metallic parts under computer control has already been demonstrated, and commercial RPLM machines for building production parts are already being marketed.The paper includes a survey of current and proposed data formats for communication between the various stages of the RPLM process. In comparing them, particular attention is given to the issue of extensibility to meet future needs. In this last respect, special emphasis is given to materials-related and other non-geometric information needed for fabricating multi-material objects and objects with graded material properties. [Copyright &y& Elsevier]
RAPID prototyping, FUSED deposition modeling, SURFACES (Geometry), CURVES, and MECHANICAL behavior of materials
Purpose – This paper aims to develop a new slicing method for fused deposition modelling (FDM), the curved layer adaptive slicing (CLAS), combining adaptive flat layer and curved layer slicing together. Design/methodology/approach – This research begins with a review of current curved layer and adaptive slicing algorithms employed in the FDM and further improvement of the same, where possible. The two approaches are then integrated to develop the adaptive curved layer slicing based on the three-plane intersection method for curved layer offsetting and consideration of facet angles together with the residual heights for adaptive slicing. A practical implementation showed that curved layer adaptive layers respond in similar lines to the flat layer counterparts in terms of the mechanical behaviour of FDM parts. Findings – CLAS is effective in capturing sharply varying surface profiles and other finer part details, apart from imparting fibre continuity. Three-point bending tests on light curved parts made of curved layers of varying thicknesses prove thicker curved layers to result in better mechanical properties. Research limitations/implications – The algorithms developed in this research can handle relatively simple shapes to develop adaptive curved slices, but further developments are necessary for more complex shapes. The test facilities also need further improvements, to be able to programmatically implement adaptive curved layer slicing over a wide range of thicknesses. Practical implications – When fully developed and implemented, CLAS will allow for better FDM part construction with lesser build times. Originality/value – This research fills a gap in terms of integrating both curved layer and adaptive slicing techniques to better slice and build a part of given geometry using FDM. [ABSTRACT FROM AUTHOR]
Layered manufacturing in rapid prototyping is to fabricate prototypes by using a laser beam to trace the cross-sectional contours of a product layer by layer. Such cross-sections of geometrical objects differ by layers and generally have more than one continuous contour in each layer. In an attempt to facilitate an efficient approach for path planning, the problem is simplified by approximating each of the continuous contours with its minimum circumscribed circle. The tool path planning for traversing all the contours in the same cross-section can then be simplified as the path planning of circles. Finding the shortest path for three circles is fundamental to solving the more general problem. In this paper, the problem of finding the minimum traversal path of three circles is transferred to the problem of finding the minimum traversal path of one circle and two points. By using the concepts of light reflection and accompanied by geometric mathematics, the equation of the minimum traversal path of three circles is derived. By analyzing the initially obtained eight roots, the two-root solution function is derived. This solution function can be used for applications including robotic motion planning and path planning for submarines, ships, and airplanes. [ABSTRACT FROM AUTHOR]
This paper proposes a multi-material virtual prototyping system for digital fabrication of heterogeneous prototypes. It consists mainly of a topological hierarchy-sorting algorithm for processing slice contours, and a virtual simulation system for visualisation and optimisation of multi-material layered manufacturing (MMLM) processes. The topological hierarchy-sorting algorithm processes the hierarchy relationship of complex slice contours. It builds a parent-and-child list that defines the containment relationship of the slice contours, and subsequently arranges the contours in an appropriate sequence, which facilitates toolpath planning for MMLM by avoiding redundant tool movements. The virtual simulation system simulates MMLM processes and provides stereoscopic visualisation of the resulting multi-material prototypes for quality analysis and optimisation of the processes. [Copyright &y& Elsevier]
Abstract: With the development of layered manufacturing or rapid prototyping, modeling heterogeneous object with varying material distribution has become more and more important. Different from homogeneous object modeling, the heterogeneous object modeling contains not only geometry and topology information but also material information. In this paper, a new method of modeling heterogeneous object is presented. In this method, firstly, the geometric model of an object is represented by the signed distance field; next, each grid is assigned with material property and material distance field which has the same resolution with geometric distance field are calculated according to material feature; the geometric and material distance field are then unified, named as multi-color distance field. The complex heterogeneous object can also be obtained via the boolean operations of multi-color distance field. For a heterogeneous object represented by the distance field, the most significant advantage is that its geometry model and material information can easily be sliced into a series of 2D layers, so it is convenient for the heterogeneous object to be fabricated using layered manufacturing machine. Several examples show the validity of our modeling method. [Copyright &y& Elsevier]
Karunakaran, K., Suryakumar, S., Pushpa, Vishal, and Akula, Sreenathbabu
International Journal of Advanced Manufacturing Technology. Dec2009, Vol. 45 Issue 7/8, p690-703. 14p. 13 Color Photographs, 3 Diagrams, 4 Charts, 2 Graphs.
MANUFACTURING processes, MACHINING, RAPID prototyping, ARTIFICIAL neural networks, and OPERATIONS research
Subtractive manufacturing [computer numerical controlled (CNC) machining] has high quality geometric and material properties but is slow, costly, and infeasible in some cases. On the contrary additive manufacturing (rapid prototyping) has total automation but compromises quality. A hybrid layered manufacturing process presented in this study combines the best features of both these approaches. It uses arc weld deposition for building near-net shapes, which are subsequently finish machined. Time and cost savings of this process can be attributed to reduction in NC programming effort and elimination of rough machining. It is envisioned as a low cost retrofitment to any existing CNC machine for making metallic objects without disturbing its original functionalities. Near-net shape building and finish machining happening at the same station is the unique feature of this process. A customized software generates the NC program for near-net shape building. The intricate details of integrating arc welding unit with a CNC milling machine are presented in this paper. [ABSTRACT FROM AUTHOR]
Beal, V., Erasenthiran, P., Hopkinson, N., Dickens, P., and Ahrens, C.
International Journal of Advanced Manufacturing Technology. Oct2006, Vol. 30 Issue 9/10, p844-852. 9p. 9 Diagrams, 3 Charts, 3 Graphs.
LASER fusion, SCANNING probe microscopy, RAPID prototyping, SOLID freeform fabrication, MANUFACTURING processes, and DIE castings
In recent years, research has been undertaken on manufacturing of functionally graded materials (FGM) using layered manufacturing technologies (LMT), also commonly known as rapid prototyping (RP), solid free-form fabrication (SFF) etc. The use of LMT to build complex FGM parts could meet optimum engineering design for various applications such as high performance die casting tools. In this context, H13 tool steel is considered a suitable material because of the high resistance to thermal fatigue and dimensional stability. Nevertheless, H13 with a low heat conduction coefficient is not thermally efficient for certain part geometries. With this in mind, the use of functionally graded techniques to disperse copper to specific regions/volumes of a H13 mould could lead to higher performance of the tool. The laser fusion of different proportions of Cu (0, 25 and 50% by weight) powder dispersed in H13 were analysed in this work. Additionally, different laser strategies were used to statistically analyse effects with respect to the composition of Cu. It was found that the refill strategy produces better results compared to all other scanning methods. The H13 with 25% Cu mix produced a homogeneous structure but cracks were observed along the cross section of the 25% Cu specimens. The pure H13 had a lower porosity with fine dendrite structures. The H13 with 50% Cu produced a non-homogeneous structure. This paper also discusses the microhardness tests results with respect to Cu composition and scanning strategy. Also, in order to identify the effect of powder composition layer on the subsequent layers and the cooling rate effect, samples were produced and analysed. One started with 100% H13 and ended with H13+50% Cu while the other started with H13+50% Cu and ended with 100% H13. [ABSTRACT FROM AUTHOR]