Embossing and Press Forming

Embossing and press forming are thermomechanical glass forming methods. They are especially important because the viscosity of glasses continuously changes as function of temperature (see Fig. 1.11). Commonly a glass is 

Cooling of the formed glass article tc reduce stress 

The direct press forming of a glass melt (see also Sect. 3.3.2) is commonly used for the forming of optical elements, such as lenses. A review of the historical development and a comparison of the processes used to produce traditional glass articles can be found in [409]. The following press forming and embossing processes to produce precise optical lenses are used  

The microstructuring of different glasses by embossing was investigated by Schubert et al. [455]. Using complex-structured tools such as etched silicon tools complex geometries were also made. 

The surface layer of the tool which will be in contact with the glass provides major challenges for all pressing and embossing techniques. This layer must be of perfect surface quality because its surface topography is replicated into the formed glass part. The tool surface has to be of sufficient wear and chemical 

---

ASTM 255 124 Inserts in wood, plastics, bolt anchors, founding cores and patterns, embossing dies, press-form blocks, dupUcating plaster patterns, mbe bending, and hobbyist pans... 

The process involves formation of a carbon perform by a low-cost slurry molding process. The pre-form is pressed and a flow field pattern is embossed in the surfaces. The porosity of the plate is then filled to the desired density by chemical vapor infiltration. 

Extrusion is the most commonly adopted shaping process used in the structural ceramic industry. The majority of products receive their final shape directly by means of the extrusion process. This does also apply to extruded roofing tiles, but these may, however, be subjected to ftirther forming, that is re-pressed, for example in the manufacture cambered tiles and to obtain an embossed surface. Slabs are extruded for the production of pressed roofing tiles, the final shape of which is achieved by a repressing process. 

Sprigging. The decoration of pottery vases, etc., by affixing clay figures (frequently classical) or other motifs to form a bas-relief. The figures are pressed in a biscuit pottery mould separately from the ware and are made to adhere to the ware by means of clay slip (cf. embossing). 

In the hot-embossing process a heated die carrying the negative of the conductor layout presses a specially coated copper film on to a thermoplastic substrate, applying thermal loading and mechanical pressure. The die cuts out the film, forming a positive bond to the locally melted plastic close to the surface of the blank. Figure 3.16 shows the process chain in simplified, schematic form. 

---