Reza Gheisari, Paulo Bártolo, Nicholas Goddard and Marco Andre das Neves Domingos
The use of microstereolithography (μSL) parts as micro-injection molding (μIM) tools greatly reduces the time and cost to product and offers unique solutions for complex design…
Abstract
Purpose
The use of microstereolithography (μSL) parts as micro-injection molding (μIM) tools greatly reduces the time and cost to product and offers unique solutions for complex design issues. However, they present challenges to designers because of their strength, thermal characteristics and shorter lifetimes as compared to other mold materials. The purpose of this study is to use SL to build rapid injection mold tools directly combining micro features for short-run production.
Design/methodology/approach
In total, three tool inserts were produced. Two different μSL mold inserts were produced and evaluated in terms of different build approaches of micro features. One of the inserts includes micro features built horizontally, while the other one collaborates features built vertically, both having same geometrical dimensions. To evaluate the replication capability of prototype tools, two different thicknesses were set for micro features, that is, 30 and 120 μm. The mold inserts were assembled on a metallic mold frame and tested with polypropylene (PP).
Findings
It was observed that using inappropriate resin to fabricate the mold inserts can lead to inaccurate geometrical dimensions of the tool. Therefore, the material with high glass transition temperature (Tg) and low thermal conductivity is preferred. Also, the results of this research work showed that the processed material and technology play an important role both on part quality and tool life. After investigating the tool failure mechanisms during the injection, it was observed that tool failure occurred mainly because of excessive flexural stresses and ejection forces during the cavity filling and part ejection phases, respectively.
Originality/value
The paper describes the capability of μSL mold inserts for the production of small batches of micro-cantilevers which are used in MEMS relays.
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Keywords
Stephen Ball, Judith Mudd, Marie Oxley, Mike Pinnock, Hazel Qureshi and Elinor Nicholas
This paper explores how a research‐based understanding of outcomes in social care can be incorporated into practice. Drawing on research by the Social Policy Research Unit and the…
Abstract
This paper explores how a research‐based understanding of outcomes in social care can be incorporated into practice. Drawing on research by the Social Policy Research Unit and the practical experience of North Lincolnshire Social Services Department, this paper highlights how culture change and the involvement of stakeholders are key to using outcomes ideas as a motivational framework for service improvement.
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We have on many occasions drawn attention to the all too prevalent fallacy of judging the nutritive and dietetic value of foods solely by their chemical composition without regard…
Abstract
We have on many occasions drawn attention to the all too prevalent fallacy of judging the nutritive and dietetic value of foods solely by their chemical composition without regard to the digestibility of the foods, and to the more or less prevalent idiosyncrasies of the public in connection with such foods. In an excellent article in The Times, Sir Wyndham Dunstan observes that “it has to be remembered that, however desirable the constituents of a given material may seem, in order to be of real value that material must be digestible— capable of assimilation within the body. In this matter of digestion people differ greatly and there must be latitude in the choice of food. While consumption in quantity of uncooked green and other vegetables is widely advocated, many are unable easily to digest some vegetables unless cooked, and not always then except in very moderate amount. Many other factors have to be taken into account in planning a common dietary. There are different tastes and preferences. The appeal a particular food makes to the individual and the appetite it stimulates are important points. The psychological factor plays a significant part and must be met by providing as wide a selection of palatable food as possible. These are a few truisms often overlooked.” With regard to the kind of bread we should eat and ought to be made to eat in war‐time, the writer observes that “there is unanimity in regarding a wholemeal bread (not always the same thing as “brown” bread) as that which should be generally eaten and readily procured. This is not at present the rule. Should it be made so? The constituents of wholemeal bread supply not only nourishment for the body but protection against ill‐health. Some of the more valuable constituents are absent from the white bread, so long the staple of this country, because they have been removed in the conversion of the wheat into white flour, which is now often further whitened and further deteriorated by a chemical bleaching agent. White bread is therefore a sophisticated and inferior food to which we have grown so accustomed that its use has become an ingrained habit. The obvious course in the circumstances, especially in war‐time, would be to compel the use of wholemeal bread and prohibit white bread. But, though such a course would be for the good of the nation, a sudden change of the kind, however beneficial, is bound to be inconvenient, if not distasteful, to many who are attached to white bread, and particularly to those who do not, or cannot, understand the need for change. There are people who say they can digest white bread more easily than “brown.” Thus it happens that the Ministry of Food, advised by numerous experts and confronted with numerous objectors, is apparently in favour of the evasive alternative of restoring artificially to white bread one at least of the valuable constituents it has lost in manufacture without impairing its whiteness. At first it was intended to do this by adding to white flour suitable quantities of two chemically prepared substances, one a vitamin and the other a calcium compound. Recently the synthetic vitamin only has been indicated as the proposed addition. This seems a clumsy and unnecessary concession to sentiment, involving considerable expenditure. It has been widely critised and regarded as “faking” bread. An eminent physician, Sir Ernest Graham Little, while condemning the proposal on general grounds, also questions its efficacy. Why first remove a natural constituent of wheat in making flour and then afterwards, at a cost, add to the flour this constituent artificially manufactured: He presents a convincing case for the use of wholemeal bread. With regard to the argument that some people dislike wholemeal bread and find it less easy to digest, it may be doubted whether many of them have eaten true wholemeal. “Brown” breads, including bread made with coarse ground wheat or bran and also several varieties of “brown” bread sold under largely advertised names, are almost everywhere procurable at higher prices than white bread. Fine wholemeal bread as well as flour is less easy to find. Large numbers of people eat very little bread, and it is therefore of small importance to them whether it is wholemeal or white. They consume far less than the three‐quarters of a pound a day included in Sir William Bragg's basal diet and make up for it with other foods which they can afford to buy. A really nutritious bread chiefly concerns the poorer classes, who eat much more bread than those better off. For the poor the substitution of wholemeal bread for white is a matter of far‐reaching importance. It has been stated that in many places wholemeal is dearer than white, but inquiries in the trade suggest that this is not as it should be, apart from “fancy” brown breads. As has been pointed out, the Ministry of Food, confronted with alternatives, apparently favour the introduction of “faked” white bread rather than the adoption of wholemeal. There is, however, a medium course. In this country we have come to recognise the “inevitability of gradualness,” and the medium course would meet present needs and might lead to the voluntary adoption of all that is desired.— It has been found that the admixture with fine ground wholemeal flour of about 10 per cent. of white flour makes a light coloured, very palatable, and digestible bread of good texture. Its nutritive value is very little less than that of full wholemeal bread; in fact a rather larger proportion of white flour would be permissible. The mixed flour is quite satisfactory for rolls, scones and cakes.” If an admixture of the kind suggested would overcome the prejudice against wholemeal bread and render it palatable to those people who dislike the ordinary wholemeal bread, there would seem to be a very strong case for adopting such a suggestion rather than first to remove a natural constituent of wheat and subsequently, at a cost, artificially add to the flour the constituent which has been removed in the manufacture of the flour.
Index by subjects, compiled by K.G.B. Bakewell covering the following journals: Facilities Volumes 8‐17; Journal of Property Investment & Finance Volumes 8‐17; Property Management…
Abstract
Index by subjects, compiled by K.G.B. Bakewell covering the following journals: Facilities Volumes 8‐17; Journal of Property Investment & Finance Volumes 8‐17; Property Management Volumes 8‐17; Structural Survey Volumes 8‐17.
Compiled by K.G.B. Bakewell covering the following journals published by MCB University Press: Facilities Volumes 8‐18; Journal of Property Investment & Finance Volumes 8‐18;…
Abstract
Compiled by K.G.B. Bakewell covering the following journals published by MCB University Press: Facilities Volumes 8‐18; Journal of Property Investment & Finance Volumes 8‐18; Property Management Volumes 8‐18; Structural Survey Volumes 8‐18.
Compiled by K.G.B. Bakewell covering the following journals published by MCB University Press: Facilities Volumes 8‐17; Journal of Property Investment & Finance Volumes 8‐17;…
Abstract
Compiled by K.G.B. Bakewell covering the following journals published by MCB University Press: Facilities Volumes 8‐17; Journal of Property Investment & Finance Volumes 8‐17; Property Management Volumes 8‐17; Structural Survey Volumes 8‐17.
Index by subjects, compiled by K.G.B. Bakewell covering the following journals: Facilities Volumes 8‐18; Journal of Property Investment & Finance Volumes 8‐18; Property Management…
Abstract
Index by subjects, compiled by K.G.B. Bakewell covering the following journals: Facilities Volumes 8‐18; Journal of Property Investment & Finance Volumes 8‐18; Property Management Volumes 8‐18; Structural Survey Volumes 8‐18.
Compiled by K.G.B. Bakewell covering the following journals published by MCB University Press: Facilities Volumes 8‐18; Journal of Property Investment & Finance Volumes 8‐18;…
Abstract
Compiled by K.G.B. Bakewell covering the following journals published by MCB University Press: Facilities Volumes 8‐18; Journal of Property Investment & Finance Volumes 8‐18; Property Management Volumes 8‐18; Structural Survey Volumes 8‐18.
Compiled by K.G.B. Bakewell covering the following journals published by MCB University Press: Facilities Volumes 8‐17; Journal of Property Investment & Finance Volumes 8‐17;…
Abstract
Compiled by K.G.B. Bakewell covering the following journals published by MCB University Press: Facilities Volumes 8‐17; Journal of Property Investment & Finance Volumes 8‐17; Property Management Volumes 8‐17; Structural Survey Volumes 8‐17.