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Advances in rapid prototyping and machining have resulted in reduced lead times for injection moulding tooling. Comparisons between aluminium and stereolithography (SL) tools are made with regard to the ejection forces required to push mouldings from the tools, heat transfer through the tools and the surface roughness of the tools. The results show that ejection forces for both types of tools are increased when a longer cooling time prior to ejection is used. The ejection forces required from a rough aluminium tool are considerably higher than those from a smooth aluminium tool. SL tools do not appear to be subjected to any smoothing as a result of moulding polypropylene parts. The rubber like nature of the tool’s surface is as a direct consequence of the low glass transition temperature and low thermal conductivity of the tool material. Further potential benefits of the low thermal properties of the tool are discussed.

This paper aims to present the application aspect of the work to manufacturing premolar and molar dental crowns by selective laser melting (SLM) of pure gold. Over the years different metals have been processed using laser-based Additive Manufacturing processes, but very little work has been published on the SLM of gold (Au). Previously published work presented suitable processing parameters for SLM of pure gold.

Suitable processing parameters were used to manufacture premolar and molar dental crowns using SLM system. Different layer thickness was used to analyse the effect on surface quality of crowns. Mechanical properties are checked using nanoindentation and micro Computerized Tomography scanning.

Dental crowns were successfully manufacturing using new build platform and suitable processing parameters. Parts were manufacturing using minimal supports which prevented parts from damaging during removal. A bed temperature of 100°C was found suitable for reducing warpage in the layers. Layer thickness of 50μm was found to have better surface quality and structural integrity as compared to 75μm. Porosity was found to be predominantly inter-layer. Small difference in mechanical properties of dental crowns is associated with the laser processing.

This research is the first of its kind which presents dental crown manufacturing using SLM of pure gold.

The purpose of this paper is to present the findings on jet array instabilities of molten caprolactam. Initial investigations showed that although a suitable range of parameters was found for stable jetting, there were cases where instabilities occurred due to external sources such as contamination.

The inkjet system consisted of a melt supply unit, filtration unit and printhead with pneumatic and thermal control. A start‐up strategy was developed to initiate the jetting trials. A digital microscope camera monitored the printhead nozzle plate to record the jet array stability within the recommended range of parameters from earlier research. The trials with jet instabilities were studied to analyse the instability behaviour.

It was found that instabilities occurred in three forms which were jet trajectory error, single jet failure and jet array failure. Occasionally, the jet with incorrect trajectory remained stable. When a jet failed, bleeding of melt from the nozzle due to the actuations influenced the adjacent jets initiating an array of jets to fail similar to falling dominos.

The research concept is novel and investigating the jet array instability behaviours could give an understanding on jetting reliability issues.

Introduces the concept of using technologies collectively known as rapid prototyping (RP) for the manufacture of end‐use products rather than prototypes, and presents recent examples. Gives details of a cost analysis performed by De Montfort University and Delphi Automotive Systems (France). Discusses the findings from the cost analysis along with opinions generated from an Internet based conference held from November 2000 to January 2001. The combination of findings from the cost analysis with expert opinions generated by the Internet conference have helped to identify the potential future for rapid manufacturing. In particular covers the issues of material properties, quality control and identification of suitable products.

Different metals have been processed using laser‐based solid freeform fabrication (SFF) processes but very little work has been published on the selective laser melting (SLM) of gold (Au). The purpose of this paper is to check the properties of gold powder and identify suitable processing parameters for SLM of 24 carat gold powder.

A full factorial approach was used to vary the processing parameters and identify suitable processing region for gold powder. The effects of laser processing parameters on the internal porosity of the multi‐layer parts were examined.

The gold powder was found to be cohesive in nature with apparent and tap densities of 9.3 and 10.36 g/cm³, respectively. The reflectance of gold powder was found to be 85 per cent in the infrared range. A very narrow good melting region was identified for gold powder. The balling phenomenon was observed at both low and high scan speeds. The size of droplets in the balling region tended to increase with increasing laser power and decreasing scan speeds. The porosity in gold multi‐layer parts was found to be the minimum for a laser power of 50 W and scan speed of 65 mm/s where most of the porosity was found to be inter‐layer porosity.

This research is the first of its kind directly processing 24 carat gold using SLM, identifying the suitable processing parameters and its effect on the internal porosity and structure of multi‐layer parts.

To develop a rapid manufacturing process for high‐volume free from fabrication of parts that is based on the high speed printing method which is screen printing. This technique will also be applied for printing in general.

This method involves continuous change in a layer's pattern (negative image of the layer) according to a very thin slice of the object to be printed. Three adaptive screen printing methods are proposed as an alternative to two dimensional screen printing. A comparative analysis is conducted and the possibility of combining the method is proposed.

Each of the three methods studied required further work as they all had major constraints. However, their combination may be the solution to the development of a rapid manufacturing process.

The originality is in the adaptive screen principle the screen being used will be capable to auto‐change the pattern of the layer to be printed instead of introducing a new stencil for every layer as in conventional screen printing.

Focuses on the recent boom in research on rapid prototyping (RP), particularly in the area of eliminating the stepped surface of the RP model, as evidenced by the papers expounded at the 5th European Conference on Rapid Prototyping and Manufacturing, held in Helsinki. Reports that Europe is lagging behind the USA in all aspects of RP, and relates suggestions from the conference to improve on this position.

An outline of the current activities in the Rapid Manufacturing (RM) Group at Loughborough University, one of the new Innovation Research Centres funded by the Engineering and Physical Science Research Council (EPSRC). A description is given of the facilities available for research and some of the projects underway – laminated tools for die casting, laser fusion of functionally‐graded materials, and design for RM. Another activity is the industrial Consortium that helps its members in the application of RM technologies. Three Consortium projects are described: deep slot tooling production using copper plated rapid prototype (RP) produced electrodes, cost reduction through RP‐produced patterns for investment casting, and production of thin walled investment cast components with RP‐built low thermal conductivity tooling.

Some time ago, a writer in these columns entered a plea for a series of reprints of notable books which had been allowed to drop entirely out of print, and certain lists of such works were printed. So far nothing seems to have come of this useful suggestion, and no publisher has had the enterprise to experiment with a few issues on the lines laid down. Instead, every British publisher is engaged in the old, old game of reprinting edition after edition of the same old classics, and venturing no further than the limits of this or that hundred “best books.” The result is that we find publishers tumbling over each other in their eagerness to produce editions of the same hackneyed classics, each slightly different from its fellow in some trifle of price, shape, size, binding or editorial annotation. The book‐shops are filled with these rival reprints, and gradually, because of a craze for over‐daintiness, their stocks are beginning to look more and more like those of the stationers who deal largely in pocket‐books and diaries. Dainty little editions of Shakespeare, Scott, Dickens, Bunyan, and similar chestnuts, abound in every variety of limp leather and gilt‐edged prettiness, and all of them are warranted to survive about half‐a‐dozen readings before their dainty beauty fades, and they are ready for the waste‐paper basket. The leading idea of most of the publishers of these delicate editions seems to be that books are no longer intended to be kept on shelves, but should be carried about like watches or toothpicks. Waistcoat‐pocket dictionaries, fountain‐pen‐pocket editions of “Don Quixote,” and breeches‐pocket editions of the London Directory are all the rage, and people are urged to buy this or that dainty classic with binding designed by Blank, R.A., not because it is a good serviceable edition of a great literary classic, but because it forms such a pretty ornament for the pocket. The sixpenny reprint has been done to death, and now the shilling and two‐shilling net edition of the book possessed by everybody is beginning to go the same way. The literature of England is one of its chief treasures, and we are never weary of boasting of its power, extent, and variety. And our leading publishers, to prove the truth of the boast, keep on multiplying the same limited selection of books in the same way, while hundreds, equally good, are neglected. It never seems to occur to the diligent publishers who issue their trumpery little editions of Shakespeare, printed on thin paper, bound in limp leather, and edited to death by some learned scholar, whose notes smother the original text, that the masterpieces of some other author would come as an absolute novelty, and be hailed as a relief from the never‐ending stock classic. Public Libraries and students of literature are compelled to buy at a great comparative cost such of the older, out‐of‐print hooks as they may desire to possess, while in many cases they are unable to Vol. IV. No. 44, February, 1902.