Showing papers on "Stamping published in 2005"

Epoxy resins as stamps for hot embossing of microstructures and microfluidic channels

Abstract: Fabrication of micro total analysis systems using plastic substrates has become more prevalent in the recent literature with the driving force being the development of inexpensive disposable analytical devices. Hot embossing is one polymer micro-fabrication method that has shown significant promise in this area because identical polymeric devices can be produced using a master to repeatedly stamp an image into a number of plastic substrates/materials. One major disadvantage of hot embossing in a research setting is the time and expense needed to produce a stamping tool able to withstand the temperature and stress of the embossing process. This paper describes a method of producing an epoxy stamp that is relatively inexpensive, rapid to produce and durable enough to withstand multiple embossing cycles (n > 50). The epoxy-stamping tool can be micro-molded from either a positive or a negative imaged master and is compatible with a number of materials including SU-8 resist on silicon, PDMS or glass. The low viscosity of the pre-cured epoxy permits the reproduction of microstructures with dimensions below 1m in size and allows for the transfer of these small structures to PMMA by hot embossing without loss in detail. The stamp fabrication process can be performed in less than 4 h. When the process is combined with rapid device prototyping capabilities of SU-8/silicon micro-fabrication the entire process of microchip fabrication process (design to device) may be completed in 24–48 h. © 2004 Elsevier B.V. All rights reserved.

An experimental study of in-plane large shear deformation of woven fabric composite

Abstract: Textile composites used as structural components have attracted more and more attention due to their superior properties and efficient stamping operations. However, formability of textile composite sheets, restricted by failure mechanisms such as wrinkling, remains as a crucial and challenging issue. Although in stamping of real parts, wrinkling depends on many factors, this paper mainly focuses on the in-plane characterization of pure shear deformation and its contribution to wrinkling. A comprehensive experimental study on woven fabric composites is presented. Modified picture frame tests were conducted up to wrinkling. The effect of test conditions was investigated, and the reduction of yarn width was found to be a key for wrinkling. The onset of wrinkling was determined by a densification method and by a laser scanning technique. Moreover, the cross-sectional profiles of fabric samples during the test were traced, helping to build up a theoretical model of the composite sheets during their large shear deformation.

The effect of process temperature on the formability of polypropylene based fibre-metal laminates

Abstract: In developing a methodology for a robust stamp-forming process for glass–fibre reinforced thermoplastic Fibre–Metal Laminate (FML) systems, an understanding of the effects of process variables on critical formability measures is required. This study recognises temperature as the primary process condition and investigates the thermal profile of an FML for a range of potential processes. These profiles have been applied to the stamping of a channel section and their success quantified using shape error, bend radius and delamination measures. It was found that it is necessary to pre-heat the laminate to 160 °C followed by rapid transfer to the press tooling which should be heated to 80 °C. Once formed, the part should be held between the die and punch until the polymer has solidified. Significant improvements in shape error were achieved compared to monolithic aluminium formed with the same process. This indicates that in addition to providing significant weight savings, FML systems have potential for superior formability characteristics compared to monolithic aluminium material systems for large volume production of components using stamp forming.

High Resolution Printing of DNA Feature on Poly(methyl methacrylate) Substrates Using Supramolecular Nano-Stamping

Abstract: In recent years, a large number of devices based on organic and biological materials have been developed. To scale-up the production of these systems to industrially acceptable standards, there is a need to develop soft-material stamping approaches with the needed resolution, complexity, and versatility. We have recently developed a DNA-based stamping method (supramolecular nano-stamping, SuNS) that has superior resolution and can print multiple molecules at the same time. A similar technique was independently developed by Crooks and co-workers. Here we show that SuNS can be used to efficiently print DNA features on a polymeric substrate (poly(methyl methacrylate), PMMA) with a 40 nm point resolution and a coverage that exceeds 100 mum2. The stamped PMMA substrate was also used as a master to print on a gold substrate. With PMMA being optically clear and electrically insulating, future applications of SuNS to print DNA micro- and nanoarrays are envisioned.

Reactive Surface Micropatterning by Wet Stamping

Abstract: Hydrogel stamps are used to reactively micropattern various types of substrates. The method, called reactive wet stamping (r-WETS), is general in nature and overcomes several limitations of conventional soft-lithographic techniques. Illustrative applications of r-WETS in surface wettability modification, deposition of metallic microstructures, preparation of supports for electrostatic self-assembly, and multistep reactive patterning are discussed.

Method of utilizing a contact printning stamp

Abstract: A method of using a contact printing stamp, including forming a transfer material on a plurality of stamping surfaces. The plurality of stamping surfaces are disposed on a plurality of stamp protrusions adapted from the forming of a stamp material in a plurality of recessed regions formed in an exposed end-region of a multilayer thin film structure.

Influence of elastic strains on the mask ratio in glassy polymer nanoimprint

Abstract: During glassy polymer nanoimprint, a supported film is extruded from protruding (punch) to recessed (cavity) regions of a patterned stamp The completeness of this extrusion determines the mask ratio for lithographic applications We show that, for a given punch contact size, there is a residual layer of unextruded material with a mean thickness that is independent of initial film thickness, stamping time, or applied maximum load Depth sensing indentation enables us to monitor deformation during the imprinting as well as after, and so understand the deformation process involved It is found that both the geometry and mean thickness of the residual layer are influenced by the overall elastic properties of the stamping system

Effects of dust particles and layer properties on organic electronic devices fabricated by stamping

Abstract: The mechanical properties of organic semiconductor thin films are determined using nanoindentation. The measured mechanical properties are incorporated into finite element simulations of deformation that arise during cathode patterning of organic electronic devices by pressure stamping methods. Simulations show that dust particles interposed between the stamp and film surface affect the evolution of contact areas when silicon or compliant polydimethyl-siloxane stamp dies are employed. We also examine the effects of the transferred metal layer thickness and stamp bulk modulus. Experimental and modeling results are found to be in good agreement. The implications of the results are discussed for the fabrication of a range of organic electronic devices.

Springback Calibration Using Pulsed Electromagnetic Field

Abstract: In stamping practice, springback of the blank is often compensated by developing the shape of the blank, which provides the targeted shape after its springback In this paper we attempt to address the root cause of springback phenomenon dictated by residual stresses in the blank after completion of the stamping process New process of springback calibration has been developed based upon the idea of elimination of elastic residual stresses in stamped blank This technology attempts to address the issues of sheet material variability and stamping process variations, which make geometrical compensation more difficult Simple set of experiments demonstrated that formed blank can be clamped to the targeted shape and then subjected to pulsed electromagnetic field

Evaluation of stamping lubricants at various temperature levels using the ironing test

Abstract: Lubricants are employed in stamping operations in order to (a) improve the material flow into the die cavity, (b) reduce wear and galling in the die and (c) obtain good surface finish of the part. Process conditions such as high temperatures and pressures could cause the lubricant to fail, thus resulting in galling or tearing of the part, damage to the tooling, and lost production. Therefore, selection of an appropriate lubricant based on the process conditions is important in the stamping industry. Several benchmark tests emulating stamping operations have been developed and are used to evaluate the performance of candidate lubricants. The major drawback of most of these tests is their inability to emulate high contact pressures and sliding velocities, which are crucial parameters for lubricity, especially in the case of high-speed progressive or transfer die operations involving ironing. Moreover, most of these tests are conducted at room temperature, while in reality; the process temperature can reach as high as 200 °C. The ironing tribotest developed at the Engineering Research Center for Net Shape Manufacturing (ERC/NSM) induces high contact pressures and temperatures, thus emulating the conditions in a production environment. Application of the test to screen candidate lubricants for stamping operations involving the ironing process is discussed in this paper.

Window component stock transferring

Abstract: An apparatus for automatic feeding of elongated sheet stock from a stamping station into a roll forming station in a window component production line includes a transfer mechanism, a feed mechanism and a controller. The transfer mechanism is between the stamping station and the roll forming station. The feed mechanism is positioned at an entrance to the roll forming station. The controller is in communication with the stamping station, the transfer mechanism and the feed mechanism. The controller is programmed to engage stock material that extends from the stamping station with the transfer mechanism, transfer the stock material paid out by the stamping station to the feed mechanism, and drive the feed mechanism to feed the elongated sheet stock into the roll forming station.

Apparatus and methods for preparing identification features including pharmaceutical applications

Abstract: Semi-automated or automated manufacturing of micro- or nanostructured identification features on objects and compositions, and especially pharmaceutical compositions. In particular, a motorized stamping apparatus capable of precise hot embossing with or without closed-loop control of the loading; a modular stamp head for a high-throughput parallel stamping apparatus that comprise an array of compact, error-tolerant, individually temperature-controllable stamping elements; inexpensive stamp holders for said elements, as well as associated methods. The inventive features do not reside in the method of making the stamps.

Stamp for patterning, method for manufacturing such stamp and method for manufacturing an object using the stamp

Abstract: A stamp for patterning onto a receiving surface of an object (101) according to a defined pattern (P) comprises a stamping surface (21) of a resilient diaphragm (20). The stamping surface is planar at rest. The pattern is reproduced on the stamping surface and the diaphragm is affixed to a rigid body (13) along a peripheral edge, so that a middle part of the diaphragm can move along a direction perpendicular to the stamping surface. The diaphragm (20) is more flexible near the peripheral edge than in the middle part. Then, the pattern (P) printed on a pseudo-spherical receiving surface (103) using the stamp exhibits few distortion.

Process for multi-position mold pressing with feeding once and automatic mold cutting and stamping machine

Abstract: An embossing technology featuring that after the paper is fed once, the embossings can be conducted at more working positions includes such steps as delivering paper, embossing at multiple positions by multiple embossing unit, and receiving paper. An automatic cutting-thermopminting machine is composed of a paper delivering unit, an embossing unit with move than two mechanics for performing the thermoprinting, stamping, and cutting, and a paper receiving unit.

Platform exercise apparatus

Abstract: A platform exercise apparatus includes a planar platform adapted for use on a floor and elevated therefrom with an elevating portion. A plurality of holes extend through the planar platform and define attachment bars therebetween. Elastic bands are provided having attachment hooks on one end thereof and a handle on the other end thereof. The elastic bands are selectively detachably attachable to the attachment bars with the hooks. The apparatus is used for exercise by standing thereon, grasping one or more of the handles and stretching the elastic bands. The apparatus is produced by injection molding the planar platform together with the elevating portion. Alternatively, the apparatus is made from a sheet of metal having the perimeter edges thereof bent to form the elevating portion, and by cutting or stamping the holes through the platform for thereby forming the attachment bars. An exercise bench can be used with the apparatus by positioning above the planar platform for thereby retaining the apparatus.

Magnetic field sensor

Abstract: The sensor has a sensor arrangement (22) with a sensor unit that responds to a magnetic field, where the arrangement and a part of connecting-conductors are coated with plastic. The conductors are designed as a stamping grid (12) with a latching for the arrangement. The grid is formed as a three-dimensional structure in an area adjacent to a transmitter arrangement (44) and supports the sensor arrangement on a frontal section (50). An independent claim is also included for a method of manufacturing a magnetic field sensor.

A New Robot-Based Sheet Metal Forming Process

Abstract: This paper describes a new sheet metal forming process for the production of sheet metal components for limited-lot productions and prototypes. The kinematic based generation of the shape is implemented by means of a new forming machine comprising of two industrial robots. Compared to conventional sheet metal forming machines this newly developed sheet metal forming process offers a high geometrical form flexibility and also shows comparatively small deformation forces for high deformation degrees. The principle of the procedure is based on flexible shaping by means of a freely programmable path-synchronous movement of the two robots. The sheet metal components manufactured in first attempts are simple geometries like truncated pyramids and cones as well as spherical cups. Among other things the forming results could be improved by an adjustment of the movement strategy, a variation of individual process parameters and geometric modifications of the tools. Apart from a measurement of the form deviations of the sheet metal with a Coordinate Measurement Machine rasterised and deformed sheet metals were used for deformation analyses. In order to be able to use the potential of this process, a goal-oriented process design is as necessary as specific process knowledge. In order to achieve process stability and safety the essential process parameters and the process boundaries have to be determined.

Polymer Thin-Film Transistor Arrays Patterned by Stamping

Abstract: We present a process to stamp semiconductor polymers suitable for the parallel fabrication of thin-film transistor island arrays. This process is compatible with roll-to-roll fabrication. When a chemically treated elastomeric stamp is pressed against a substrate previously coated with the polymer solution, a capillary force drives the polymer solution into the stamp recesses. Simultaneously, the raised features of the stamp in contact with the substrate absorb the solvent. The resulting polymer thin film reproduces the pattern of the raised features of the stamp. Features with lateral dimensions as small as 2 μm are faithfully reproduced. We use this stamping process to fabricate arrays of polymer thin-film transistors (TFTs) using poly(fluorene-co-bithiophene) and poly(thiophene) semiconductors.