Design limits of unbonded laminate tooling for pressure die-casting

This paper describes a new concept for the construction of prototype tooling specifically for pressure die-casting. The tools are made by clamping together laser-cut profiles in H13 tool steel sheet. The result of this endeavour has been the creation of a low cost, flexible, scalable and robust tooling system for design validation that allows multiple design iterations to be examined on the actual pressure die-casting equipment used in the production environment. Work to date has shown that relatively large up-standing features can withstand the forces of molten metal during injection

A model for weld strength in ultrasonically consolidated components

Ultrasonic consolidation (UC) is a solid freeform fabrication technique developed for the manufacture of metal parts. The mechanisms by which bonds are formed, during the UC process, are based on a combination of the surface effect and the volume effect. Based on the outcomes of peel tests and microstructural analysis, this paper will consider the influence of these two phenomena on the weld strength of specimens. A model is presented to describe how calculations for weld strength may be derived on the basis of the theory of surface and volume effects. Through the application of the model, it was possible to demonstrate that the weld strength may be 7 per cent greater than the tensile strength of the base metal. The identification of the phenomena and the development of a model for weld strength have led to the modification and production of an enhanced test procedure which is described in this paper

Freeform construction application research

The level of automation technology and processes control, within the construction sector, faces unique challenges if it is to catch up with automotive and aerospace applications. The construction industry has problems relating to health and safety, environmental legislation and traditional methods of procurement. These are compounded by diminishing skills in the labour force. One way to address these issues is by increased automation and integration of design, modelling and process control. Digital Fabrication has demonstrated the feasibility of the integration of design and component production on a large scale. Freeform Construction builds on Digital Fabrication by integrating the control of final material deposition. This paper reports on recent meetings held with industrialists to gauge their perceptions of the technology and encourage discourse to identify both applications and opportunities for the wider research community. Examples of digital fabrication in construction are discussed. Freeform Construction is defined and potential applications are presented. An example of physical model generation from construction CAD software is described

From MPA to strategically designed absorbers using solid freeform fabrication techniques

This paper reports on current work investigating the development of an alternative single material, broad frequency acoustic resonator by applying geometric changes to the cavity, without using sub-millimetre features. The inclusion of internal features such as fins and perforated layers are considered. The manufacture of these complex components is possible directly from CAD data via relatively new manufacturing techniques collectively know as Rapid Manufacturing. The technology has limitations for this application which are explored in the paper. Significant resistance however, has been achieved without the use of resistive materials or sub-millimeter features and significant improvements in peak absorption and increases in bandwidth over ¾ of an octave have been attained. These findings are currently being utilised in the development of a broad frequency absorber

Freeform construction: mega-scale rapid manufacturing for construction

The utilisation of automation technology and processes control found in the automotive and aerospace industries is not paralleled in modem day construction. The industry also struggles to improve health and safety issues and still uses traditional methods of procurement. These problems are compounded by the diminishing skills in the labour force. Methods of production must change if these issues are to be resolved. Rapid Manufacturing is a family of digitally controlled additive processes that have the potential to impact on construction processes. This paper outlines some of the major issues facing construction technology and gives examples of the use of large scale Digital Fabrication in the industry. The term 'Freeform Construction' is defined. Potential applications derived from an industrial workshop are presented and results from a series of preliminary studies indicate the viability of mega-scale Rapid Manufacturing for construction. (c) 2006 Elsevier B.V. All rights reserved

Design data issues for the control of mega-scale rapid manufacturing

Construction has traditionally relied on specifications and 2D drawings to convey material properties, performance details and location information. The use of advanced 3D solid modelling and digital fabrication methods are enabling the construction of Iconic buildings with an emphasis on the visual design of form. The integration of function with structure, however, has not yet been realised. Rapid manufacturing technologies are able to create physical objects directly from 3D solid modelling data by computer controlled additive processes. Components can be produced with any geometric form and can add further value through integrating function. Large scale versions of these processes are now being investigated for construction applications and an important aspect of these machines are the build instructions. These are created in a series of discrete steps from the design concept, encapsulated in the digital model, through to the machine code instructions. The use of the language used to describe precision, accuracy, tolerance, resolution and minimum feature size are blurred by the use of manufacturing based processes applied to create a new type of construction. This paper explores these issues and offers definitions of these terms in relation to mega-scale freeform fabrication processes for construction

Surface temperature of tools during the high-pressure die casting of aluminium

The objective of this work was to determine the temperature experienced within a pressure die-casting tool during aluminium part production. It was important to determine the temperature profile of the production process so that an accurate thermal cycle could later be simulated. The research overcame several challenges of this aggressive environment to show that the surface temperature of a die could be obtained from an H13 steel tool running on an aluminium pressure die-casting machine. The results show that the surface of a typical aluminium pressure die-casting tool heats to 400-450°C within approximately 1 s and cools to 150-200°C within approximately 20 s

A new fatigue test procedure for die-casting tool materials

The objective of this research was to investigate a new test procedure for simulating the temperatures in die casting so that materials can be evaluated as tool materials for the high-pressure die casting of aluminium. Other procedures have been used for evaluating the thermal fatigue performance of tool materials, but these tests do not reproduce all the conditions found in production environments. A new test method has been established that enables the thermal fatigue resistance of materials to be identified. The test is robust, reliable, and versatile and has a large operating temperature range (25-1200°C), and the cycle times and dwell times are adjustable. The results have shown a similar number of cycles to induce the same level of fatigue cracking as in actual die-casting tools. The performance of different materials can be compared, and an approximate fatigue life for high-pressure die-casting tools can be determined

Applying future industrialised processes to construction

Construction has traditionally relied on specifications and 2D drawings to convey material properties, performance details and location information. Advanced 3D solid modelling and digital fabrication methods are growing in construction. Iconic building design is driving the industry towards a new era of the Building Information Model (BIM) where a building is modelled entirely using 3D solid CAD tools containing all the required information for construction. CNC machinery can utilise this information to manufacture components enabling highly bespoke and non-repeating components to be cost competitive. Rapid Manufacturing machines also use this information to build components by selectively adding material rather than the traditional subtractive or formative processes. The BIM drives current machines for the production of models for inspection or to explore assembly issues. Recent developments are scaling up these processes so that whole building components can be built using a mega scale, additive machine. This paper explores some of the issues relating to the design of building components and discusses issues on the implementation of these process

The potential of freeform construction processes

The level of automation technology and processes control found in modern day construction lags significantly behind other industries such as automotive and aerospace. The construction industry has health and safety issues and still uses traditional methods of procurement. These problems are compounded by diminishing skills in the labour force. Methods of production must change if these issues are to be resolved and Freeform Construction is a collection of processes that could have potential impact. This paper outlines some of the major issues facing construction and sets a context with examples of digital fabrication in construction. Freeform Construction is defined and potential applications are presented and related to application scale. The viability of two potential applications are investigated in terms of cost