Purpose – This paper surveys the current state and capabilities of three dimensional printing (3DP). A comprehensive review of 3D Printing applications is presented. The scope of the applications includes design, manufacturing, the medical field and architecture. Design/methodology/approach – A large variety of manufacturing applications such as rapid pattern making and rapid tooling using the 3DP process directly or as core technology, as well as further implications in design and engineering analysis, medicine, and architecture are presented and evaluated. Findings – Some research issues are also discussed. An attempt, based on the state of the art, to show weaknesses and opportunities, and to draw conclusions about the future of this important process rounds up this paper. Research limitations/implications – The scope of this research survey is limited to evaluation and comparison of processes that may be characterised as 3D printing technologies. Practical implications – The study is very useful as a basis for matching evaluated 3D printing machine and process capabilities to user requirements, and forms a framework on which future comparative studies can build. Originality/value – A comprehensive overview of the capabilities of 3DP processes is presented and evaluated. It shows the application of 3D printing beyond concept modelling. The paper is valuable for researchers as well as individuals, who require adequate and relevant comparative information during decision making.

Background: All the reported measures of sitting posture, as well as photographs, have one flaw, as these measures are external to the body. These measures use calculations from external bony landmarks to estimate spinal posture, on the understanding that what is being measured externally reflects the shape, health and performance of structures of the underlying spine. Without a comparative measure of the relative position of the structures of the spine, the validity of any external spinal posture measure cannot be established. This paper reports on a study which tests the validity of photographs to measure adolescent sitting posture. Methods: The study was conducted in a laboratory at the Department of Human Biology, University of Cape Town. A random sample of 40 adolescents were recruited from the Cape metropolitan schools, to detect differences of three degrees or more between the repeated measures of upright, normal or slouched posture (photographs) and between the posture photographs and LODOX measures. Eligible participants were healthy male and female subjects aged 15 or 16 years old, in Grade 10, and who were undertaking Computer or Computype studies at their schools. Two posture measurement tools were used in the study, namely: Photographs were taken using the Photographic Posture Analysis Method (PPAM) and Radiographs were taken using the LODOX (LODOX (Pty) Ltd) system. Subjects' posture was assessed in simulated computer workstations. The following angles were measured: the sagittal head angle, cervical angle, protraction/retraction angle, arm angle and the thoracic angle. Results: Data from 39 subjects (19 males, 20 females) was used for analysis (17 15-year-olds (7 boys and 10 girls), 22 16-year-olds (12 boys and 10 girls)). All but one photographic angle showed moderate to good correlation with the LODOX angles (Pearson r values 0.67–0.95) with the exception being the shoulder protraction/retraction angle Pearson r values. Bland Altman limits of agreement illustrated a slight bias for all angles. The reliability study findings from repeated photographs demonstrated moderate to good correlation of all angles (ICC values 0.78–0.99). Conclusion: The findings of this study suggest that photographs provide valid and reliable indicators of the position of the underlying spine in sitting. Clinically it is important to know whether a patient is showing true progression in relation to a postural intervention. Based on the results of this study, the PPAM can be used in practice as a valid measure of sitting posture.

Purpose – The research was undertaken to characterise the three dimensional printing (3DP) process in term of the achievable dimensional and geometric accuracy. Design/methodology/approach – New benchmark models were developed that represent characteristics needing to be investigated. The parts were fabricated in different materials. A program was written to measure the features on a numerically controlled coordinate measurement machine. Finally, a statistical analysis was done. The results are reported in terms of statistical parameters and international tolerance (IT) grades. Findings – The paper provides general IT grades of the 3DP process for parts printed using different materials (powders). Research limitations/implications – The research is limited to specific materials and equipment. Practical implications – The data is very useful for designing products to be manufactured on 3DP machines applying either direct or indirect methods. Originality/value – 3DP is more and more used for rapid prototyping with great potential towards rapid manufacturing. Designers need to know the capability profile of the process they are going to use. There is a significant lack of published data on the 3DP process characteristics. This research was conducted to fill this gap and provide much needed accuracy information.

This paper presents a tactile sensor consisting of an array of force sensing resistors (FSRs). The tactile sensing array can be seen as a coordinated system of touch sensors. The low spatial resolution measured with the FSRs compared to other force or pressure sensors required the use of a super-resolution algorithm. Super-resolution algorithms are often used in digital image processing to enhance the resolution of images. Multiple images taken from slightly different orientations are superimposed in such a way that a single higher-resolution image is obtained. Different touch sensors are briefly discussed and the use of FSRs is motivated. Image-registration techniques are discussed and the super-resolution algorithm developed for the application is presented. Some tests performed using the tactile sensor in a neck palpation device and the results of these tests are also presented.

Purpose: The purpose of this paper is to demonstrate the use of three‐dimensional printing (3DP) process as a base technology for rapid manufacturing of components, larger than the machine's build volume. This extends the 3DP applications field beyond its existing domain. The paper gives process chains and design for manufacturing and assembly guidelines.Design/methodology/approach: Several parameters influencing the process chains are identified and their interrelations investigated. Based on this study, new process chains are developed for specific functional and material requirements. The new process chains are validated with several case studies. Where applicable, the process chains are compared qualitatively with existing methods.Findings: The results show that the new process chains are as fast as or faster than existing methods and have similar accuracy. The most significant advantage is a more geometric freedom. There is also more opportunity for checking physical models before making the final part. Some limitations to the processes are identified and given as design guidelines.Research limitations/implications: A quantitative comparison of existing methods with the new process was not possible.Practical implications: The study provides useful design for manufacturing guidelines.Originality/value: This paper shows how 3DP technology, originally only conceived as a concept modeller, can be used to manufacture components that are larger than the rapid prototyping machine's build volume. It gives guidelines for designers wishing to follow a similar route.