Experimental and numerical investigation on micro deep drawing process of stainless steel 304 foil using flexible tools

Flexible forming technology provides significant application potential in various areas of manufacturing, particularly at a miniaturized level. Simplicity, versatility of process and feasibility of prototyping makes forming techniques by using flexible tools suitable for micro sheet metal forming. This paper reports the results of FE simulation and experimental research on micro deep drawing processes of stainless steel 304 sheets utilising a flexible die. The study presents a novel technique in which an initial gap (positive or negative) is adopted between an adjustment ring and a blank holder employed in the developed forming system. The blank holder is moveable part and supported by a particular spring that provides the required holding force. The forming parameters (anisotropy of SS 304 material, initial gap, friction conditions at various contact interfaces and initial sheet thickness) related with the forming process are in details investigated. The FE models are built using the commercial code Abaqus/Standard. The numerical predictions reveal the capability of the proposed technique on producing micro metallic cups with high quality and large aspect ratio. To verify these results, number of micro deep drawing experiments is conducted using a special set up developed for this purpose. As providing a fundamental understanding is required for the commercial development of this novel forming technique, hence the optimization of the initial gap in accordance with each sheet thickness, thickness distribution and punch force/stroke relationship are detected

Nano/microfabrication of three-dimensional device structures using a multilayered mould approach

There is growing interest in the development of fabrication techniques to cost effectively mass-produced high-resolution (micro/nano) three-dimensional structures in a range of materials. Biomedical applications are particularly significant. This work demonstrates how to fabricate simultaneously a sacrificial mould having the inverse shape of the desired device structure and also create the desired device structure using electrodeposition techniques. The mould is constructed of many thin layers using a photo-resist material that is dissolvable and sensitive to ultraviolet (UV) light. At the same time the device is created in the emerging mould layers using gold electrodeposition technique. Choosing to fabricate the mould and the three-dimensional structures in multiple thin layers allows for the use of UV light and permits the potential cost-effective realization of three-dimensional curved surfaces, the accuracy and geometric details of which are related to the number of layers used. An example is provided to explain the novel fabrication process and to outline the resulting design and fabrication constraints