Emerald

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.

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.

A good match is found between the IR images and the material flaws detected by metallographic techniques.

First results are presented here, mechanisms of flaw formation and transfer between build layers are not addressed in detail.

This work has important implications for quality assurance in SEBM and rapid manufacturing in general.

This paper presents a new indirect scaffold fabrication method for soft tissue based on rapid prototyping (RP) technique and preliminary characterization for collagen scaffolds.

This paper introduces the processing steps for indirect scaffold fabrication based on the inkjet printing technology. The scaffold morphology was characterized by scanning electron microscopy. The designs of the scaffolds are presented and discussed.

Theoretical studies on the inkjet printing process are presented. Previous research showed that the availability of biomaterial that can be processed on a commercial RP system is very limited. This is due mainly to the unfavorable machine processing parameters such as high working temperature and restrictions on the form of raw material input. The process described in this paper overcomes these problems while retaining the strength of RP techniques. Technical challenges of the process are presented as well.

Harnessing the ability of RP techniques to control the internal morphology of the scaffold, it is possible to couple the design of the scaffold with controlled cell‐culture condition to modulate the behavior of the cells. However, this is just initial work, further development will be needed.

This method enables the designer to manipulate the scaffold at three different length scales, namely the macroscopic scale, intermediate scale and the cellular scale.

The work presented in this paper focuses on important processing steps for indirect scaffold fabrication using thermal‐sensitive natural biomaterial. A mathematical model is proposed to estimate the height of a printed line.

The objective of this paper is to develop geometric algorithms and planning strategies to enable the development of a novel hybrid manufacturing process, which combines rapidly re‐configurable mold tooling and multi‐axis machining.

The presented hybrid process combines advantages of both reconfigurable molding and machining processes. The mold's re‐configurability is based on the concept of using an array of discrete pins. By positioning the pins, the reconfigurable molding process allows forming the mold cavity directly from the object's 3D design model, without any human intervention. After a segment of the part is molded using the reconfigurable molding process, a multi‐axis machining operation is used to create accurate parts with better surface finish. Geometric algorithms are developed to decompose the design model into segments based on the part's moldability and machinability. The decomposed features are used for planning the reconfigurable molding and the multi‐axis machining operations.

Computer implementation and illustrative examples are also presented in this paper. The results showed that the developed algorithms enable the proposed hybrid re‐configurable molding and multi‐axis machining process. The developed decomposition and planning algorithms are used for planning the reconfigurable molding and the multi‐axis machining operations. Owing to the decomposition strategy, more geometrically complex parts can be fabricated using the developed hybrid process.

This paper presents geometric analysis and planning to enable the development of a novel hybrid manufacturing process, which combines rapidly re‐configurable mold tooling and multi‐axis machining. It is expected that the proposed hybrid manufacturing process can produce highly customized parts with better surface finish, and part accuracy, with shorter build times, and reduced setup and tooling costs.

The purpose of this paper is to describe a preliminary investigation into the heat treatment of Ti‐6Al‐7Nb components that had been produced via selective laser melting (SLM).

Bars of Ti‐6Al‐7Nb were produced using SLM by MCP‐HEK Tooling GmbH in Lubeck, Germany. These bars were then subjected to a range of heat treatments and the resultant microstructure evaluated with respect to its likely effect on fatigue.

It was found that the as received material consisted of an α′ martensitic structure in a metastable β matrix. Evidence of the layer‐wise thermal history was present, as were large (up to ∼500 μm) pores. Solution treatment at 955°C (below the β transus) did not completely disrupt this layered structure and is therefore not recommended. When solution treatment was performed at 1,055°C (above the β transus) a homogeneous structure was produced, with a morphology that depended on the post‐solution treatment cooling rate. It was concluded that the most promising heat treatment consisted of a moderate cooling rate after solution treatment at 1,055°C.

The study had only limited material and therefore it was not possible to perform any mechanical property testing.

The paper presents the initial findings of a project which is aimed at optimising the mechanical properties of Ti‐6Al‐7Nb components produced using SLM.

Currently, little is known about the heat treatment and subsequent mechanical properties of this Ti‐6Al‐7Nb alloy when produced using rapid manufacturing techniques. Such lack of knowledge limits the potential applications, especially in the biomedical field where the consequences of implant failure are high. The paper presents the first step in developing this understanding.

This paper seeks to investigate the possibility of producing medical or dental parts by selective laser melting (SLM). Rapid Manufacturing could be very suitable for these applications due to their complex geometry, low volume and strong individualization.

The SLM‐process has been optimized and fully characterized for two biocompatible metal alloys: Ti‐6Al‐4V and Co‐Cr‐Mo. Mechanical and chemical properties were tested and geometrical feasibility, including process accuracy and surface roughness, was discussed by benchmark studies. By developing a procedure to fabricate frameworks for complex dental prostheses, the potential of SLM as a medical manufacturing technique has been proved.

Optimized SLM parameters lead to part densities up to 99.98 percent for titanium. Strength and stiffness, corrosion behavior, and process accuracy fulfil requirements for medical or dental parts. Surface roughness analyses show some limitations of the SLM process. Dental frameworks can be produced efficiently and with high precision.

This study presents the state‐of‐the‐art in SLM of biocompatible metals by thoroughly testing material and part properties. It shows opportunities for using SLM for medical or dental applications.

The purpose of this paper is to identify the key elements of a new rapid prototyping process, which involves layer‐by‐layer deposition of liquid‐state material and at the same time using an ultraviolet line source to cure the deposited material. This paper reports studies about the behaviour of filaments, deposition accuracy, filaments interaction and functional feasibility of system. Additionally, the author describes the process which has been proposed, the equipment that has been used for these studies and the material which was developed in this application.

The research has been separated into three study areas in accordance with their goals. In the first, both the behaviour of filament and deposition accuracy was studied. The design of the experiment is described with focus on four response factors (bead width, filament quality, deposition accuracy and deposition continuity) along with function of three control factors (deposition height, deposition velocity and extrusion velocity). The author also studied the interaction between filaments as a function of bead centre distance. In addition, two test samples were prepared to serve as a proof of the methodology and to verify the functional feasibility of the process which has been studied.

The results show that the proposed process is functionally feasible, and that it is possible to identify the main effects of control factors over response factors. That analysis is used to predict the condition of process as a function of the parameters which control the process. Also identified were distances of centre beads which result in a specific behaviour. The types of interaction between filaments were analysed and sorted into: union, separation and indeterminate. At the end, the functional feasibility of process was proved whereby two test parts could be built.

This paper proposes a new rapid prototyping process and also presents test studies related to this proposition. The author has focused on the filament behaviour, deposition accuracy, interaction between filaments and studied the functional feasibility of process to provide new information about this process, which at the same time is useful to the development of other rapid prototyping processes.