Metal based rapid prototyping for more complex shapes

In the last 18 months a new Rapid Prototyping process involving direct deposition of metal has been under development at Cranfield University. The process entails the use of a Gas Metal Arc fusion welding robot which deposits successive layers of metal in such way that it forms a 3D solid component. A solid model is first drawn using a CAD system, then data indicating the kind of layers and dimension is incorporated and the solid is automatically sliced. This slicing routine also generates reports on the welding time and conditions for the production of the component and automatically generates the robot program. Depending on the complexity of the component the time from drawing the component to being ready to press the start button of the robot to make the component can take less than two hours. An example of a component which was generated to test the system is described here in order to illustrate how the process is operated, the quality of the component, and the productivity which may be expected

Rapid prototyping process using metal directly

Rapid Prototyping emerged in the USA in the late 80’s and it made the whole industry rethink their way of making prototypes. Several new different process have emerged since then and these vary in materials, times, prices, finishing quality, etc. However, not many have achieved acceptable results with using 100% pure metal. Some heavy industry want prototypes made with metal in order to assess not only the shape of the prototype but also its hardness conditions and functionality of the component in real situations. This technique is still under development at several different places and although some research have been done recently the results are not yet as desired. In the last couple of years a Rapid Prototyping process involving direct deposition of metal had been under development (as a PhD research) at Cranfield University. The process entails the use of a Gas Metal Arc fusion welding robot which deposits successive layers of metal in such way that it forms a 3D solid component. A solid model is first drawn using a CAD system, then data indicating the kind of layers and dimension is incorporated and the solid is automatically sliced. This slicing routine also generates reports on the welding time and conditions for the production of the component and automatically generates the robot program. Depending on the complexity of the component, the time from drawing the component to being ready to press the robot start button to make the component can take less than a couple of hours. Several test components were produced with good characteristics and perfectly acceptable surface finishing. This paper describes the process and shows some samples

A 'Square to Round' shape made using metal based rapid prototyping

In the last 18 months a new Rapid Prototyping process involving direct deposition of metal has been under development at Cranfield University. The process entails the use of a Gas Metal Arc fusion welding robot which deposits successive layers of metal in such way that it forms a 3D solid component. A solid model is first drawn using a CAD system, then data indicating the kind of layers and dimension is incorporated and the solid is automatically sliced. This slicing routine also generates reports on the welding time and conditions for the production of the component and automatically generates the robot program. Depending on the complexity of the component the time from drawing the component to being ready to press the robot start button to make the component can take less than two hours. An example of a component which was generated to test the system is described here in order to illustrate how the process is operated, the quality of the component, and the productivity which may be expected.Junta Nacional de Investigação Científica e Tecnológica

Practical case of rapid prototyping using gas metal arc welding

To prove the viability of ‘Rapid Prototyping using Fusion Welding’ the author presents an example of a component created using this process. At this stage of the work, the process is not yet completed thus some of the modules that are part of this process were generated artificially. This paper will present the following sections: 1) a basic idea of how the process works, 2) description of each step in the process, 3) software/hardware used, 4) how each module was performed on the creation of this example, 5) the resultant shape and values, 6) deviations from the planned shape and 7) some conclusions

Rapid prototyping using robot welding: process description

Rapid Prototyping is a relatively recent technique to produce component prototypes for industry in a much shorter period of time, since the time to market a product is essential to its success. A new Rapid Prototyping process which uses metal as the raw material had been under development at Cranfield University in the last few years. The process uses a Gas Metal Arc fusion welding robot which deposits successive layers of metal in such way that it forms a 3D solid component. Firstly, a CAD system is used to draw the solid model, then some information relative to the types of layers and dimensions is incorporated in the model and the solid model is then automatically sliced. Reports on the welding time and conditions for the component’s production are automatically generated as well as the robot program. The concept of this Rapid Prototyping process is deeply explained in this paper. Every step of the process is described by a full chart. The Hardware and Software used in this system are also described. Since a computer model is used a calibration of the system is required and therefore the most important aspects of Robot and Cell Calibration are also discussed

Racial Variation in Echocardiographic Reference Ranges for Left Chamber Dimensions in Children and Adolescents: A Systematic Review.

Echocardiography plays a critical role in the assessment of cardiac disease. Important differences in echocardiographically derived cardiac chamber dimensions have been previously highlighted in different population groups in adult studies, but this has not been systematically studied in children, whose body size changes throughout childhood. The aim of this study was to review the distribution of available reference ranges for the left cardiac chamber dimensions in older children and adolescents. The following electronic data bases were searched: Medline, Embase and Web of Science were searched to identify studies which have established echocardiographic reference ranges of left heart parameters in children and adolescents from 1975 to December 2017. There was no geographical limitation. All results were imported into Endnote. Retrieved articles were screened and data extracted by two independent reviewers. A total of 4398 studies were retrieved, with 36 studies finally included in this review. 29 (81%) references were from North America and European (Caucasians) populations, with only one study each from Africa and South America. Two-dimensional and M-mode techniques were the most commonly used echocardiography techniques. There were methodological variations in techniques and normalisation of references. Comparison of selected cardiac measures showed significant differences for interventricular septal thickness among Black African, Indian, German and US American children. Available echocardiographic references cannot be generalised to all settings and therefore, there is need for locally relevant reference ranges. Africa and South America are particularly under-represented. Future studies should focus on developing comprehensive echocardiographic reference ranges for children from different racial backgrounds and should use standardised techniques

La relación personal en el tratamiento de la diversidad

El autor centra su aportación en diferentes características de los organismos vivos, para incorporarlas a las perspectivas interpretativas y operativas, y de los métodos actuales de intervención educativa. En el texto también se trata el enfoque positivo desde la dimensión técnica y no «voluntarista», teniendo en cuenta que los especialistas que adoptan la perspectiva del enfoque positivo dan mucha importancia al tema de la calidad de vida.L'autor centra la seva aportació en diferents característiques dels organismes vius, per incorporar- les a les perspectives interpretatives i operatives, i dels mètodes actuals d'intervenció educativa. Al text també es tracta l'enfocament positiu des de la seva dimensió tècnica i no «voluntarista», tenint en compte que els especialistes que adopten la perspectiva de l'enfocament positiu donen molta importància al tema de la qualitat de vida.The author focuses on the different characteristics of the alive organisms in order to include them into the interpretative and operative views of the current methods of educational intervention. He also deals with the positive focus, from the technical and «no voluntary» dimension, taking into account that those specialists having this kind of view do emphasize a lot on the quality of life issue

A formalized general theory of syntax with bindings

We present the formalization of a theory of syntax with bindings that has been developed and refined over the last decade to support several large formalization efforts. Terms are defined for an arbitrary number of constructors of varying numbers of inputs, quotiented to alpha-equivalence and sorted according to a binding signature. The theory includes a rich collection of properties of the standard operators on terms, such as substitution and freshness. It also includes induction and recursion principles and support for semantic interpretation, all tailored for smooth interaction with the bindings and the standard operators