846 resultados para Machinery -- Manufacturing processes


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Abrasion by hard particles is responsible for wear in many practical situations, but can also be used constructively in grinding and polishing processes. A brief overview of abrasion is presented, followed by an historical survey of polishing and a discussion of laboratory abrasion test methods.

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Includes bibliography

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We demonstrate the capability of a laser micromachining workstation for cost-effective manufacturing of a variety of microfluidic devices, including SU-8 microchannels on silicon wafers and 3D complex structures made on polyimide Kapton® or poly carbonate (PC). The workstation combines a KrF excimer laser at 248 nm and a Nd3+:YVO4 DPSS with a frequency tripled at 355 nm with a lens magnification 10X, both lasers working at a pulsed regime with nanoseconds (ns) pulse duration. Workstation also includes a high-resolution motorized XYZ-tilt axis (~ 1 um / axis) and a Through The Lens (TTL) imaging system for a high accurate positioning over a 120 x 120 mm working area. We have surveyed different fabrication techniques: direct writing lithography,mask manufacturing for contact lithography and polymer laser ablation for complex 3D devices, achieving width channels down to 13μ m on 50μ m SU-8 thickness using direct writing lithography, and width channels of 40 μm for polyimide on SiO2 plate. Finally, we have tested the use of some devices for capillary chips measuring the flow speed for liquids with different viscosities. As a result, we have characterized the presence of liquid in the channel by interferometric microscopy.

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The changing face of industry due to the adoption of `New Technology' is briefly discussed, as are the corresponding structural changes in the workforce. The adoption of NC machinery is identified as one of the major innovations affecting the structure of industry. The development of NC machinery, and of relevant programming techniques are reviewed, and the problems arising from its initial sponsorship by the aerospace industry are highlighted. The process of its subsequent diffusion into industry is reviewed. Skill levels adopted for NC use in Britain and Germany are discussed, and analysed to create a structural pattern. These classifications of skill levels are then used to examine the organisational structures adopted by companies utilising NC machines. The greater use made of higher level shop floor skills by German companies is discussed. The results of two surveys of the use made of NC by companies in the North East of England are presented. Effective company organisation for NC use is described, and lack of foresight is shown to lead to vulnerability problems where skills can become concentrated in a few key people. This led to closure of a company in one instance. It is shown that small sub-contract companies have adopted a highly skilled shop floor workforce, and that they have survived in the present hostile economic environment, whilst companies who have used NC to de-skill the shop floor contracted dramatically in the same period. The lack of awareness of the potential for reviewing the product design in relation to the flexibility of NC, so leading to reductions in work in progress levels, is highlighted. Recommendations for skill structures appropriate to various sized companies and suitable training programs are presented to ensure that the full potential of NC machinery is achieved.

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This article categorises manufacturing strategy design processes and presents the characteristics of resulting strategies. This work will therefore assist practitioners to appreciate the implications of planning activities. The article presents a framework for classifying manufacturing strategy processes and the resulting strategies. Each process and respective strategy is then considered in detail. In this consideration the preferred approach is presented for formulating a world class manufacturing strategy. Finally, conclusions and recommendations for further work are given.