Rapid Prototyping Journal

Ian Campbell; David Bourell; Ian Gibson

2012 Rapid Prototyping Journal

doi: 10.1108/13552541211231563

Purpose – The purpose of this paper is to provide a personalised view by the Editors of the Rapid Prototyping Journal . Design/methodology/approach – It collects their years of experience in a series of observations and experiences that can be considered as a snapshot of where this technology is today. Findings – Development of these technologies has progressed according to application, materials and how the designers have applied their creativity to such a unique manufacturing tool. Originality/value – The paper predicts how the future of additive manufacturing will look from the perspective of three key elements: applications, materials and design.

Jan Schwerdtfeger; Robert F. Singer; Carolin Körner

2012 Rapid Prototyping Journal

doi: 10.1108/13552541211231572

Purpose – The purpose of this paper is to investigate the possibility of in situ flaw detection for powder bed, beam‐based additive manufacturing processes using a thermal imaging system. Design/methodology/approach – The authors compare infrared images (IR) which were taken during the generation of Ti‐6Al‐4V parts in a selective electron beam melting system (SEBM) with metallographic images taken from destructive material investigation. Findings – A good match is found between the IR images and the material flaws detected by metallographic techniques. Research limitations/implications – First results are presented here, mechanisms of flaw formation and transfer between build layers are not addressed in detail. Originality/value – This work has important implications for quality assurance in SEBM and rapid manufacturing in general.

K.P. Karunakaran; Alain Bernard; S. Suryakumar; Lucas Dembinski; Georges Taillandier

2012 Rapid Prototyping Journal

doi: 10.1108/13552541211231644

Purpose – The purpose of this paper is to review additive and/or subtractive manufacturing methods for metallic objects and their gradual evolution from prototyping tools to rapid manufacture of actual parts. Design/methodology/approach – Various existing rapid manufacturing (RM) methods have been classified into six groups, namely, CNC machining laminated manufacturing, powder‐bed technologies, deposition technologies, hybrid technologies and rapid casting technologies and discussed in detail. The RM methods have been further classified, based on criteria such as material, raw material form, energy source, etc. The process capabilities springing from these classifications are captured in the form of a table, which acts as a database. Findings – Due to the approximation in RM in exchange for total automation, a variety of multi‐faceted and hybrid approaches has to be adopted. This study helps in choosing the appropriate RM process among these myriad technologies. Originality/value – This review facilitates identification of appropriate RM process for a given situation and sets the framework for design for RM.

Juan Pablo Isaza; Alba Avila

2012 Rapid Prototyping Journal

doi: 10.1108/13552541211231707

Purpose – Deposition of ink containing metal particles is possible using inkjet technologies. The purpose of this paper is to show a novel method for deposition of iron microparticles, with an average diameter of 1.24 μm , on a glass substrate that can potentially achieve concentrations of 0.21 per cent or higher. Design/methodology/approach – The method combines drop‐on‐demand (DOD) technology with a creative way of positioning iron microparticles near to the nozzle's print head. The use of ferromagnetic particles allows the control of particle dispersion on the target sample surface. The particles are positioned close to the nozzle using a sharpened steel rod as holder and their alignment is controlled by generating an external magnetic field along the sharpened steel rod. Findings – Successful deposition of iron microparticles with a potential concentration of 0.21 per cent or higher is reported. Research limitations/implications – The implemented method is restricted to ferromagnetic particles or alloys of ferromagnetic and non‐ferromagnetic materials. Practical implications – The method described could be integrated to control the deposition of iron microparticles in the production of optoelectronic devices and biosensors. This method speeds up the deposition process due to the higher metal microparticle concentrations achieved. Originality/value – The deposition method introduced in the paper reached concentrations of 0.084 per cent, similar to the highest concentrations (0.1 per cent) reported with conventional methods (inkjet inks containing metal nanoparticles). It also prevents the blocking of the print head nozzles, thus improving the efficiency of Fe particle deposition.

Mohammad Vaezi; Chee Kai Chua; Siaw Meng Chou

2012 Rapid Prototyping Journal

doi: 10.1108/13552541211231716

Purpose – Today, medical models can be made by the use of medical imaging systems through modern image processing methods and rapid prototyping (RP) technology. In ultrasound imaging systems, as images are not layered and are of lower quality as compared to those of computerized tomography (CT) and magnetic resonance imaging (MRI), the process for making physical models requires a series of intermediate processes and it is a challenge to fabricate a model using ultrasound images due to the inherent limitations of the ultrasound imaging process. The purpose of this paper is to make high quality, physical models from medical ultrasound images by combining modern image processing methods and RP technology. Design/methodology/approach – A novel and effective semi‐automatic method was developed to improve the quality of 2D image segmentation process. In this new method, a partial histogram of 2D images was used and ideal boundaries were obtained. A 3D model was achieved using the exact boundaries and then the 3D model was converted into the stereolithography (STL) format, suitable for RP fabrication. As a case study, the foetus was chosen for this application since ultrasonic imaging is commonly used for foetus imaging so as not to harm the baby. Finally, the 3D Printing (3DP) and PolyJet processes, two types of RP technique, were used to fabricate the 3D physical models. Findings – The physical models made in this way proved to have sufficient quality and shortened the process time considerably. Originality/value – It is still a challenge to fabricate an exact physical model using ultrasound images. Current commercial histogram‐based segmentation method is time‐consuming and results in a less than optimum 3D model quality. In this research work, a novel and effective semi‐automatic method was developed to select the threshold optimum value easily.

Annalisa Tirella; Carmelo De Maria; Giuseppe Criscenti; Giovanni Vozzi; Arti Ahluwalia

2012 Rapid Prototyping Journal

doi: 10.1108/13552541211231725

Purpose – The traditional tissue engineering approach employs rapid prototyping systems to realise microstructures (i.e. scaffolds) which recapitulate the function and organization of native tissues. The purpose of this paper is to describe a new rapid prototyping system (PAM‐modular micro‐fabrication system, PAM 2 ) able to fabricate microstructures using materials with different properties in a controlled environment. Design/methodology/approach – Computer‐aided technologies were used to design multi‐scale biological models. Scaffolds with specific features were then designed using custom software and manufactured using suitable modules. In particular, several manufacturing modules were realised to enlarge the PAM 2 processing material window, controlling physical parameters such as pressure, force, temperature and light. These modules were integrated in PAM 2 , allowing a precise control of fabrication parameters through a modular approach and hardware configuration. Findings – Synthetic and natural polymeric solutions, thermo‐sensitive and photo‐sensitive materials can be used to fabricate 3D scaffolds. Both simple and complex architectures with high fidelity and spatial resolution ranging from ±15 μm to ±200μm (according to ink properties and extrusion module used) were realised. Originality/value – The PAM 2 system is a new rapid prototyping technique which operates in controlled conditions (for example temperature, pressure or light intensity) and integrates several manufacturing modules for the fabrication of complex or multimaterial microstructures. In this paper it is shown how the system can be configured and then used to fabricate scaffolds mimicking the extra‐cellular matrix, both in its properties (i.e. physic‐chemical and mechanical properties) and architecture.

Manlio Bordoni; Alberto Boschetto

2012 Rapid Prototyping Journal

doi: 10.1108/13552541211231734

Purpose – The purpose of this paper is to propose a new way of prototyping surfaces, taking the mathematical background into account, without involving drawing environments. Design/methodology/approach – The authors thicken surfaces from a mathematical point of view to obtain solids. Next they look for an operative procedure to build virtual models and interchange files. The authors build a sample of Enneper thickened surface by fused deposition modelling and verify the prototype by reverse engineering techniques. Findings – The authors provide a formulation able to thicken surfaces in mathematical terms. An operative procedure generates virtual solids and interchange files in the same environment. The approximations necessary for additive fabrication, such as triangulations and mesh geometry, can be chosen at this stage. Research limitations/implications – The approach is useful at the product/process development stage, in which surfaces are delivered by theoretical analysis. At this stage a prototype can give useful advice permitting functional tests. The limitation is that, when the mathematical formulation is not available, it is difficult to translate a concept without fundamentals of differential geometry. Practical implications – Approximations of drawing environments typically lead to fault models, not ready for fabrication by additive manufacturing (AM) technologies, needing empiric, not at all obvious and not rapid repair interventions. The authors' approach eliminates this stage, permitting a faster and simple managing of modifications due to functional and technological requirements, that are frequent at concept stage. This leads to a time‐to‐market reduction in the course of product/process development. Originality/value – This paper extends the capability of a mathematical approach to solve surface prototyping problems. By reducing the required stages, the proposed methodology finds a theoretical and practical shorter route to direct fabrication.

Jiang Wu; Xiaobo Wang; Xianghui Zhao; Chunbao Zhang; Bo Gao

2012 Rapid Prototyping Journal

doi: 10.1108/13552541211231743

Purpose – The purpose of this paper is to explore an application of computer‐aided design and manufacture (CAD/CAM) to a process of electronically surveying a scanned dental cast as a prior stage to producing a sacrificial pattern for a removable partial denture (RPD) metal alloy framework. Design/methodology/approach – With the introduction of laser scan technology and commercial reverse engineering software, a standard plaster maxillary dental cast with dentition defect was successfully scanned and created as a STL‐formatted digital cast. With the software, the unwanted undercuts were eliminated based on the desired path of insertion. Parts of the RPD framework were then successfully custom‐designed and combined as a whole. Findings – A sacrificial pattern was produced by rapid prototyping (RP) method and finally casted with chromium cobalt alloy. With suitable finishing process, both the sacrificial pattern and the casted framework fitted the cast well. Originality/value – The research indicated the feasibility of creating a library of RPD framework components. It is believed that, in the future, with the advance of the techniques, a totally new platform can be developed for the design and fabrication of custom‐fit RPD framework based on the CAD/CAM/RP system.

Victoria Townsend; Jill Urbanic

2012 Rapid Prototyping Journal

doi: 10.1108/13552541211231752

Purpose – The purpose of this paper is to relate additive manufacturing (AM) and machining (CNC) synergistically in a modular approach in the design and manufacturing domains, to generate value for end‐users and manufacturers (a teleological system). Design/methodology/approach – The research methodology decomposes a part into modules, by employing a teleological systems theory approach paired with principles of modular design. Modules are manufactured with either additive manufacturing (fused deposition modeling, FDM) or machining (CNC). Process selection is determined by a decision‐making framework that quantifies strength and weakness comparisons of FDM and CNC machining processes, accomplished using the analytic hierarchy process (AHP). Findings – The developed methodology and decision‐making framework is successfully applied to the design and manufacturing of a large, complex V6 engine section sand casting pattern. This case study highlights the merits of the research. Research limitations/implications – The research assumes that the processes being considered are capable of meeting the product functional requirements. The proposed methodology can be extended to evaluate additional processes. Practical implications – Value is assessed in this research relative to: time and cost opportunities, managing knowledge limitations of a process by leveraging hybrid options, and aligning design and manufacturing to create a product that accomplishes the goals of the end‐user (teleological effectiveness). Originality/value – Utilizing the AHP process and a teleological perspective are new, and proven effective, approaches in relating additive and subtractive processes in a hybrid approach with end‐user perspectives. The research demonstrates a systematic methodology to quantify additive and subtractive process selection.