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Article
Publication date: 1 March 2001

Feng Lin, Yongnian Yan and Wei Sun

A mathematical model to describe the principle of layered manufacturing and layered fabrication error is presented in this paper. In this model, the layered manufacturing

Abstract

A mathematical model to describe the principle of layered manufacturing and layered fabrication error is presented in this paper. In this model, the layered manufacturing process is characterized by the model decomposition and material accumulation. A 3D design model is represented by a set of points with sequence functions to correlate the layered processing information. Iso‐sequence planes are defined as the processing layers to collect points with the same processing sequence and to define the material accumulation along its gradient direction. Examples of using the proposed model to describe the layered manufacturing to process flat and no‐flat surfaces and the description of the layered processing error are also presented.

Details

Rapid Prototyping Journal, vol. 7 no. 1
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 May 2001

Feng Lin, Wei Sun and Yongnian Yan

A mathematical model to predict the layered process error and an optimization algorithm to define the fabricating orientation based on the minimum process error for layered

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1064

Abstract

A mathematical model to predict the layered process error and an optimization algorithm to define the fabricating orientation based on the minimum process error for layered manufacturing fabrication has been developed. Case studies to determine the preferred orientation candidates for fabricating spherical objects, cube objects and objects with irregular geometrical shapes have been conducted and the results were used to validate the sensitivity, accuracy, and capability of the developed model and optimization algorithm. Different orientation candidates determined by minimum processing error and by minimum processing time were also compared. The developed model and the optimization algorithm can be used, in conjunction with other processing parameters such as processing time and support structure, to define an optimal processing planning for layered manufacturing fabrication.

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Rapid Prototyping Journal, vol. 7 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 March 2000

Prashant Kulkarni, Anne Marsan and Debasish Dutta

Layered manufacturing (LM) is emerging as a new manufacturing technology that can enhance the scope of manufacturing. One of the essential tasks in LM is process planning…

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6920

Abstract

Layered manufacturing (LM) is emerging as a new manufacturing technology that can enhance the scope of manufacturing. One of the essential tasks in LM is process planning. This paper defines, conceptualizes and reviews the literature in this emerging area. The paper concludes with future projections on the possible directions of research in this area.

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Rapid Prototyping Journal, vol. 6 no. 1
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 20 June 2016

Sajan Kapil, Prathamesh Joshi, Hari Vithasth Yagani, Dhirendra Rana, Pravin Milind Kulkarni, Ranjeet Kumar and K.P. Karunakaran

In additive manufacturing (AM) process, the physical properties of the products made by fractal toolpaths are better as compared to those made by conventional toolpaths…

Abstract

Purpose

In additive manufacturing (AM) process, the physical properties of the products made by fractal toolpaths are better as compared to those made by conventional toolpaths. Also, it is desirable to minimize the number of tool retractions. The purpose of this study is to describe three different methods to generate fractal-based computer numerical control (CNC) toolpath for area filling of a closed curve with minimum or zero tool retractions.

Design/methodology/approach

This work describes three different methods to generate fractal-based CNC toolpath for area filling of a closed curve with minimum or zero tool retractions. In the first method, a large fractal square is placed over the outer boundary and then rest of the unwanted curve is trimmed out. To reduce the number of retractions, ends of the trimmed toolpath are connected in such a way that overlapping within the existing toolpath is avoided. In the second method, the trimming of the fractal is similar to the first method but the ends of trimmed toolpath are connected such that the overlapping is found at the boundaries only. The toolpath in the third method is a combination of fractal and zigzag curves. This toolpath is capable of filling a given connected area in a single pass without any tool retraction and toolpath overlap within a tolerance value equal to stepover of the toolpath.

Findings

The generated toolpath has several applications in AM and constant Z-height surface finishing. Experiments have been performed to verify the toolpath by depositing material by hybrid layered manufacturing process.

Research limitations/implications

Third toolpath method is suitable for the hybrid layered manufacturing process only because the toolpath overlapping tolerance may not be enough for other AM processes.

Originality/value

Development of a CNC toolpath for AM specifically hybrid layered manufacturing which can completely fill any arbitrary connected area in single pass while maintaining a constant stepover.

Details

Rapid Prototyping Journal, vol. 22 no. 4
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 19 October 2015

Yashpal Patel, Aashish Kshattriya, Sarat B Singamneni and A. Roy Choudhury

Layered manufacturing with curved layers is a recently proposed rapid prototyping (RP) strategy for the manufacture of curved, thin and shell-type parts and the repair of…

Abstract

Purpose

Layered manufacturing with curved layers is a recently proposed rapid prototyping (RP) strategy for the manufacture of curved, thin and shell-type parts and the repair of worn surfaces, etc. The present investigation indicates another possible application area. In case of flat-layered RP of computer-aided design models having randomly located, small-dimensioned but critical surface features, adaptive slicing is resorted to. Large number of thin slices have to be employed to preserve the critical features. In contrast, a considerably lower number of curved thin slices would be required to preserve such surface features in case of RP with curved layers.

Design/methodology/approach

The method of preservation of critical features by RP with curved layers is formulated and demonstrated for two clusters of critical features on the surface of a part. A minimum number of such curved layers is identified by application of genetic algorithms (GAs) in case of a simple example. GA evolves the shape of the curved layer passing through the lower cluster so as to make a curved layer pass through the upper cluster of critical features.

Findings

In the example part, a 21 per cent reduction in the number of layers is achieved by the application of adaptive curved layers over adaptive straight layers.

Originality/value

The novelty of the concept is the proposed use of curved layered RP with adaptive slicing for the preservation of critical features in final prototyped part. This methodology, applied to part with two distinct clusters, leads to reduced number of layers compared to that obtained in flat-layered RP.

Details

Rapid Prototyping Journal, vol. 21 no. 6
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 5 November 2020

Nan Zhang, Lichao Zhang, Senlin Wang, Shifeng Wen and Yusheng Shi

In the implementation of large-size additive manufacturing (AM), the large printing area can be established by using the tiled and fixed multiple printing heads or the…

Abstract

Purpose

In the implementation of large-size additive manufacturing (AM), the large printing area can be established by using the tiled and fixed multiple printing heads or the single dynamic printing head moving in the xy plane, which requires a layer decomposition after the mesh slicing to generate segmented infill areas. The data processing flow of these schemes is redundant and inefficient to some extent, especially for the processing of complex stereolithograph (STL) models. It is of great importance in improving the overall efficiency of large-size AM technics software by simplifying the redundant steps. This paper aims to address these issues.

Design/methodology/approach

In this paper, a method of directly generating segmented layered infill areas is proposed for AM. Initially, a vertices–mesh hybrid representation of STL models is constructed based on a divide-and-conquer strategy. Then, a trimming–mapping procedure is performed on sliced contours acquired from partial surfaces. Finally, to link trimmed open contours and inside-signal square corners as segmented infill areas, a region-based open contour closing algorithm is carried out in virtue of the developed data structures.

Findings

In virtue of the proposed approach, the segmented layered infill areas can be directly generated from STL models. Experimental results indicate that the approach brings us the good property of efficiency, especially for complex STL models.

Practical implications

The proposed approach can generate segmented layered infill areas efficiently in some cases.

Originality/value

The region-based layered infill area generation approach discussed here will be a supplement to current data process technologies in large-size AM, which is very suitable for parallel processing and enables us to improve the efficiency of large-size AM technics software.

Details

Rapid Prototyping Journal, vol. 27 no. 1
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 19 January 2010

Olivier Kerbrat, Pascal Mognol and Jean‐Yves Hascoet

The purpose of this paper is to propose a methodology to estimate manufacturing complexity for both machining and layered manufacturing. The goal is to take into account…

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1716

Abstract

Purpose

The purpose of this paper is to propose a methodology to estimate manufacturing complexity for both machining and layered manufacturing. The goal is to take into account manufacturing constraints at design stage in order to realize tools (dies and molds) by a combination of a subtractive process (high‐speed machining) and an additive process (selective laser sintering).

Design/methodology/approach

Manufacturability indexes are defined and calculated from the tool computer‐aided design (CAD) model, according to geometric, material and specification information. The indexes are divided into two categories: global and local. For local indexes, a decomposition of the tool CAD model is used, based on an octree decomposition algorithm and a map of manufacturing complexity is obtained.

Findings

The manufacturability indexes values provide a well‐detailed view of which areas of the tool may advantageously be machined or manufactured by an additive process.

Originality/value

Nowadays, layered manufacturing processes are coming to maturity, but there is still no way to compare these new processes with traditional ones (like machining) at the early design stage. In this paper, a new methodology is proposed to combine additive and subtractive processes, for tooling design and manufacturing. A manufacturability analysis is based on an octree decomposition, with calculation of manufacturing complexity indexes from the tool CAD model.

Details

Rapid Prototyping Journal, vol. 16 no. 1
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 December 1997

P.J. de Jager, J.J. Broek and J.S.M. Vergeest

Current rapid prototyping processes are mainly based on layered manufacturing techniques using 2.5D slices. Defines manufacturing by means of 2.5D slices as a zero order…

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581

Abstract

Current rapid prototyping processes are mainly based on layered manufacturing techniques using 2.5D slices. Defines manufacturing by means of 2.5D slices as a zero order approximation. A disadvantage of this approximation is the staircase effect, requiring thin layers to be used. If the outer surfaces of the slices can be inclined, speaks of a first order approximation. This approximation is achieved by linear interpolation between adjacent contours, resulting in ruled slices. Describes a method to approximate a given model geometry in a layered fashion not exceeding a user‐defined error δ using either a zero or a first order approximation and an adaptive layer thickness. Analyses the model geometry for curvature and inclination in order to determine the adaptive layer thickness. Provides a method for matching corresponding contours from adjacent slices. Several test objects have been processed using both zero and first order approximation. Shows that the first order approximation significantly reduces the number of required layers for a given δ when compared to the zero order approximation.

Details

Rapid Prototyping Journal, vol. 3 no. 4
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 19 July 2021

Xiaojing Feng, Bin Cui, Yaxiong Liu, Lianggang Li, Xiaojun Shi and Xiaodong Zhang

The purpose of this paper is to solve the problems of poor mechanical properties, high surface roughness and waste support materials of thin-walled parts fabricated by…

Abstract

Purpose

The purpose of this paper is to solve the problems of poor mechanical properties, high surface roughness and waste support materials of thin-walled parts fabricated by flat-layered additive manufacturing process.

Design/methodology/approach

This paper proposes a curved-layered material extrusion modeling process with a five-axis motion mechanism. This process has advantages of the platform rotating, non-support printing and three-dimensional printing path. First, the authors present a curved-layered algorithm by offsetting the bottom surface into a series of conformal surfaces and a toolpath generation algorithm based on the geodesic distance field in each conformal surface. Second, they introduce a parallel five-axis printing machine consisting of a printing head fixed on a delta-type manipulator and a rotary platform on a spherical parallel machine.

Findings

Mechanical experiments show the failure force of the five-axis printed samples is 153% higher than that of the three-axis printed samples. Forming experiments show that the surface roughness significantly decreases from 42.09 to 18.31 µm, and in addition, the material consumption reduces by 42.90%. These data indicate the curved-layered algorithm and five-axis motion mechanism in this paper could effectively improve mechanical properties and the surface roughness of thin-walled parts, and realize non-support printing. These methods also have reference value for other additive manufacturing processes.

Originality/value

Previous researchers mostly focus on printing simple shapes such as arch or “T”-like shape. In contrast, this study sets out to explore the algorithm and benefits of modeling thin-walled parts by a five-axis machine. Several validated models would allow comparability in five-axis printing.

Details

Rapid Prototyping Journal, vol. 27 no. 7
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 20 April 2015

Suryakumar Simhambhatla and K.P. Karunakaran

– This paper aims to develop build strategies for rapid manufacturing of components of varying complexity with the help of illustration.

Abstract

Purpose

This paper aims to develop build strategies for rapid manufacturing of components of varying complexity with the help of illustration.

Design/methodology/approach

The build strategies are developed using a hybrid layered manufacturing (HLM) setup. HLM, an automatic layered manufacturing process for metallic objects, combines the best features of two well-known and economical processes, viz., arc weld-deposition and milling. Depending on the geometric complexity of the object, the deposition and/or finish machining may involve fixed (3-axis) or variable axis (5-axis) kinematics.

Findings

Fixed axis (3-axis) kinematics is sufficient to produce components free of undercuts and overhanging features. Manufacture of components with undercuts can be categorized into three methods, viz., those that exploit the inherent overhanging ability, those that involve blinding of the undercuts in the material deposition stage and those that involve variable axis kinematics for aligning the overhang with the deposition direction.

Research limitations/implications

Although developed using the HLM setup, these generic concepts can be used in a variety of metal deposition processes.

Originality/value

This paper describes the methodology for realizing undercut features of varying complexity and also chalks out the procedure for their manufacture with the help of case studies for each approach.

Details

Rapid Prototyping Journal, vol. 21 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

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