Stamp forming

Other types of compression moulding and stamp forming used for continuous fibre reinforced composites are illustrated in Fig. 4.73. 

Figure 10.18 schematically illustrates the process. It uses elastomeric stamps similar those of pCP. or hard stamps formed using the etching procedures outlined in Fig. 10.10. Depositing a thin layer of solid material on to the raised features of the stamp constitutes the inking step. All of the examples described here use electron beam evaporation of a thin layer of Au (20-50 nm) or a bilayer of Au (20-50 nm)/Ti (2-5 nm).

Fig. 10.25. Multilayer thin film capacitor structure printed in a single step on to a plastic substrate using the nanotransfer printing technique. A multilayer of Au/SiNx/Ti/ Au was first deposited on to a silicon stamp formed by photolithography and etching. Contacting this stamp to a substrate of Au/ PDMS/PET forms a cold weld that bonds the exposed Au on the stamp to the Au-coating on the substrate. Removing the stamp produces arrays of square (250 pm x 250 pm) metal/...

Recently, the soft lithography [51,52] technique of micromolding in capillaries (MIMIC) [53,54] has been used to fabricate MIP micromonoliths on silicon wafers [55,56]. In MIMIC, an elastomeric stamp that possesses recessed features is placed in intimate contact with a soUd substrate. The recessed microchannels on the stamp form a network of empty capillaries. When a low-viscosity fluid precursor is placed at one end, it spontaneously fills the channels by capillary action. Curing of the fluid leaves patterned microstructures on the substrate surface as shown in Fig. 7. 

Lee, J.S., Hong Seok, J., Yu, W.-R., Kang Tae, J., 2007. The effect of blank holder force on the stamp forming behavior of non-crimp fabric with a chain stitch. Compos. Sci. Technol. 67 (3), 357-366. 

Fig. 8.3. Deformation state in a geomembrane, following the impressions with a stamp of given size. The stamp form simulates the contact area of a gravel particle on the geomembrane increased by the protective layer. The lateral dimension of the indentation was approx. 25 mm and the depth approx. 0.77 nun. Such indentations are typically seen, when protection layers are tested with 16/32 mm gravel. The calculated arch elongation eqnalled 0.25 %. However, local bending strain of the onter fibre is about ten times higher than the calcnlated arc elongation...

Wakeman W D, Zingraff L, Bourban P E and Manson J A E (2006) Stamp forming of carbon fiber/PA12 composites - A comparison of a reactive impregnation process and a commingled yarn system. Comp Sci Tech 66 19-35. 

Cabrera N O, Reynold C T, Alcock B and Peijs T (2008) Non-isothermal stamp forming of continuous tape reinforced all-polypropylene composite sheet. Compos Part A 39 1455-1466. 

Cabrera N O, Reynolds C T, Alcock B and Peijs T (2008) Non-isothermal stamp forming of continuous tape reinforced all-polypropylene composite sheet. Compos Part A 39 1455-1466. Abraham T N, Wanjale S D, Bar iny T and Karger-Kocsis J (2009) Tensile mechanical and perforation impact behavior of aU-PP composites containing random PP copolymer as matrix and stretched PP homopolymer as reinforcement Effect of beta nucleation of the matrix. Compos Part A 40 662-668. 

Several approaches have been developed that utilize PDMS stamps, formed as described above by casting PDMS onto a silicon master and curing it, as molds. In replica molding, a polymeric material (e.g., polyurethane) is formed by using the PDMS as a mold, enabUng multiple... 

Stamp forming processes are processes that form the heated organic sheet using exactly defined upper and iower stamps and quick-ciosing presses. This process enables extremely short cycle times of less than one minute. The stamp forming... 

Silicone stamp Metal stamp forming process ... 

In the pure metal stamp forming process, both mold halves are made from metal. In silicone stamp forming, one mold half is mostly made from elastic material (mostly the upper mold half). Table 1.11 shows a comparison between both processes concerning the most important features. 

Because the laminate is not in contact with the mold, the temperature loss (in comparison to the stamp forming process) worsens, which means that the cooling or cycle times increase. The service life of the mold is increased in comparison to the stamp forming process because no fiber marks occur on the mold surface due to the protection of the diaphragms so mold wear is then significantly decreased. 

In sandwich forming in multiple steps, the top layers and the core are separately transformed first and are connected in the following step [10]. A minimum of two forming molds and a various number of process steps are necessary due to the geometrical differences of the top layers. Forming should be done in separate metal stamp forming molds due to the necessary component accuracy. 

Figure 1.223 shows a metal stamp forming mold for sandwich forming with a clamping frame and a transformed component. Due to the compressibility of the core material, higher density deviations in the top layers can be tolerated, and local thickening can subsequently be integrated into the component concept without any mold modifications. 

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