The pivotal role of rapid manufacturing in the production of cost effective customised products

The concept of Rapid Manufacturing (RM) is emerging from the so-called Rapid Prototyping technologies where additive rather than subtractive techniques will be used to make parts or even completed assemblies. As no tooling is required, one of the main benefits of RM will be the ability to make cost-effective custom products that could all be entirely individualised to a particular consumer or user. Thus, Rapid Manufacturing is the enabling technology for true, cost effective custom manufacturing and has the potential to revolutionise the design and manufacturing worlds. This paper will introduce results from a current research project that is being undertaken at Loughborough University looking into the effects that will occur to the logistics and supply chain infrastructure with the advent of RM

Effect of the build orientation on the mechanical properties and fracture modes of SLM Ti–6Al–4V

Recent research on the additive manufacturing (AM) of Ti alloys has shown that the mechanical properties of the parts are affected by the characteristic microstructure that originates from the AM process. To understand the effect of the microstructure on the tensile properties, selective laser melted (SLM) Ti–6Al–4V samples built in three different orientations were tensile tested. The investigated samples were near fully dense, in two distinct conditions, as-built and stress relieved. It was found that the build orientation affects the tensile properties, and in particular the ductility of the samples. The mechanical anisotropy of the parts was discussed in relation to the crystallographic texture, phase composition and the predominant fracture mechanisms. Fractography and electron backscatter diffraction (EBSD) results indicate that the predominant fracture mechanism is intergranular fracture present along the grain boundaries and thus provide and explain the typical fracture surface features observed in fracture AM Ti–6Al–4V

Cost estimation for rapid manufacturing - laser sintering production for low to medium volumes

Rapid manufacturing (RM) is a modern production method based on layer by layer manufacturing directly from a three-dimensional computer-aided design model. The lack of tooling makes RM economically suitable for low and medium production volumes. A comparison with traditional manufacturing processes is important; in particular, cost comparison. Cost is usually the key point for decision making, with break-even points for different manufacturing technologies being the dominant information for decision makers. Cost models used for traditional production methodologies focus on material and labour costs, while modern automated manufacturing processes need cost models that are able to consider the high impact of investments and overheads. Previous work on laser sintering costing was developed in 2003. This current work presents advances and discussions on the limits of the previous work through direct comparison. A new cost model for laser sintering is then proposed. The model leads to graph profiles that are typical for layer-manufacturing processes. The evolution of cost models and the indirect cost significance in modern costing representation is shown finally

Microstructure of Ti-6Al-4V produced by selective laser melting

Ti-6Al-4V is the most widely used titanium alloy. Manufacturing of Ti-6Al-4V components using novel additive processing techniques such as selective laser melting is of great interest. This study focuses on the microstructure characterisation of Ti-6Al-4V components produced by selective laser melting (SLM) with full (Ti-6Al-4V base plate) and partial (Ti-6Al-4V needle-shaped bed) support. The starting material, a plasma atomised powder, and the component products are studied using various microscopy techniques including optical, scanning electron and transmission electron microscopy and electron backscattered diffraction (EBSD). Powder particles are fully dense, possess a spherical shape and are composed of acicular α phase. The as-built material shows oriented acicular martensitic phase with well defined columnar grains. The morphology of martensitic phase and microstructural evolution will be discussed in relation to the SLM processing parameters employed and the different cooling rates experienced by the components

Low cost optical fibre based Fabry Pérot strain sensor production

The production of Fabry-Pérot based optical fibre sensors has long been an iterative and labour intensive process. This paper demonstrates the production of Fabry-Pérot based optical fibre strain sensors using chemical etching techniques. Utilising hydrofluoric acid (HF) and singlemode optical fibres, a preferential etching mechanism was observed around the core portion of the fibres. These etched fibre ends were then spliced together successfully to form enclosed Fabry-Pérot cavities between 18 and 60 μm in length. These sensors have then been deployed for strain monitoring and have been subjected to strains of up to 1400 με on tensile test specimens. Etched Fabry-Pérot cavity lengths were monitored using a white light interferometry (WLI) system based on a CCD spectrometer and an 850 nm super luminescent diode (SLD). A linear and repeatable response to these strain tests has been shown with negligible sensitivity to temperature

An empirical laser sintering time estimator for Duraform PA

This paper presents work on the development of a build time estimator for Rapid Manufacturing (RM). A time estimator is required in order to develop a comprehensive costing tool for RM. An empirical method has been used to estimate build times utilising both simulated and actual builds for a Laser Sintering (LS) machine. The estimator presented here is based upon object geometry and therefore the fundamental data driving the model is obtainable from current three dimensional Computer Aided Design (3D-CAD) models. The aim of the paper is to define a model describing the build times for a laser sintering machine either for single or multiple objects

Rapid manufacturing – impact on supply chain methodologies and practice

This paper demonstrates the use of Rapid Manufacturing (RM) as the enabling technology for flexible manufacturing in a number of industrial sectors. The paper discusses the evolution of Rapid Prototyping (RP) to Rapid Manufacturing and the current issues that require further research for the successful integration of this technology within manufacturing companies. The use of RM will have particular impact on supply chain management paradigms such as lean and agile and has particular strategic fit with mass customisation. The effect RM will have on these paradigms is discussed and confirmed with example cases from automotive production, motor sport and medical devices industries. In conclusion RM has already been shown in the three cases to offer benefits, particularly where fast re-configuration of the manufacturing process is required and with the production of customised components

Printability of elastomer latex for additive manufacturing or 3D printing

Additive manufacturing, sometimes referred to as 3D printing is a new, rapidly developing technology which has the potential to revolutionize fabrication of certain high value, complex products. Until now conventional elastomers have not been widely used in the additive manufacturing process. The goal of our work was to determine the feasibility of additive manufacturing using ink jet printing of elastomeric latex materials. Particle size, viscosity, and surface tension were measured for five different latex materials—poly(2-chloro-1,3-butadiene), carboxylated styrene-butadiene rubber, carboxylated butadiene-acrylonitrile copolymer, natural rubber, and prevulcanized natural rubber. The XSBR latex was predicted as the one most likely to be printable. Printing trials carried out with the XSBR as the ink proved it to be printable, although technical problems of agglomeration and print head clogging need to be addressed and both the material and process need to be optimized for consistent printing to be achieved

Rapid manufacturing facilitated customisation

This paper presents a novel method for the production of body-fitting customised seat profiles utilising the following digital methods: three dimensional laser scanning, reverse engineering and Rapid Manufacturing (RM). Seat profiles were manufactured in order to influence the comfort characteristics of an existing ejector seat manufactured by Martin Baker Aircraft Ltd. The seat, known as the Navy Aircrew Common Ejection Seat (NACES), was originally designed with a generic profile. This paper shows the replacement of this profile with shapes captured from fast jet pilots. Pressure mapping of occupied seats, has shown that the pressure distribution under the buttocks can be influenced using body-fitting design and thus comfort is directly affected. The paper discusses the relevance of RM with respect to mass customisation and personalisation and, in addition, recognises RM as a Next Generation Manufacturing System (NGMS) capable of satisfying increasingly diverse products and lower volume production. A generic customisation process is reviewed to identify areas of technical difficulty and key issues in the cost-effective customisation of products

The formation of [alpha] + [beta] microstructure in as-fabricated selective laser melting of Ti–6Al–4V

Ti–6Al–4V parts made by the additive manufacturing (AM) technique selective laser melting (SLM) generally show poor ductility due to their fine martensitic microstructure. This study was designed to assess whether a more suitable microstructure can be obtained when long laser/material interaction times are used. As-fabricated components with an [alpha] + [beta] microstructure were produced and characterized with various microscopy techniques. The microstructural evolution was discussed in relation to the build platform temperature, the cyclic reheating, and the thermal stresses that developed during the process. The hardness of the samples was also evaluated and discussed. The hardness varied in relation to the different microstructure morphologies observed in the samples and different partitioning of the alloying elements. This study indicates a methodology through SLM to obtain Ti–6Al–4V with an as-deposited [alpha] + [beta] microstructure which is more desirable than that the typical fully martensitic microstructure typically obtained after SLM