Injection stamping

CD-ROM disks are nearly identical to the weU-known compact disk-digital audio (CD-DA short CD). The information on a CD-ROM is stamped in the form of clearly defined pits on the disk surface during the disk s manufacture, using injection mol ding or injection stamping techniques. A metal stamper transfers the digital information to the disk s surface. 

The birefringence for phenyl-substituted PC (4) (T = 176 C) is reduced to about 50%, for benzyl substituted PC (5) (T = 138 C) to about 25%, and for four-ring bisphenol PC (6) to 8% of the value for BPA-PC (183,190,195,197,198) on condition of an optimum conformation of the phenyls in the side groups perpendicular to the aromatic rings in the backbone. In reaUty, however, these low birefringence values are not achieved, because the optimum conformation of the phenyl rings cannot be achieved in injection-stamped disks. 

This process, which has been used at least since the early 1940s (1), combines the best of injection molding and compression molding. The process also is called injection-compression or injection-stamping. Basically it involves using an IM machine (Chapter 2) to melt a plastic (unreinforced or reinforced TP or TS) and direct a fixed amount of the melt into a compression mold (Chapter 6). As shown in Fig. 8-3, a compression mold has a male plug that fits into a female mold. 

Injection-molded articles can be decorated by in-mold labeling or by post-mold decoration. In the former method, printed film is inserted into the mold cavity before injection. The plastic forms an intimate contact with the graphic material. Post-mold decoration includes hot stamping, dry offset printing, and decal printing. 

In the manufacture of shaft seals, the molding is the process where the compound and treated metal stamping (phosphated and adhesive applied) are brought together to form the conventional lip type shaft seal. Therefore, it is critical that the compounds used are formulated to suit the molding process. There are three fundamental molding processes in use today compression, injection, and injection/transfer. 

Hand Layup. Compression. Injection. Spray Jp. Vacuum Bag, Autoclave, RTM. RtM, Rotational. Stamping. Autocalve. Coining... 

Sublimation (diffusion) printing is a textile process in which color patterns in dry die crystals are transferred from a release film to the fabric under high heat and pressure. The process has been adapted to plastics. The equipment used is very similar to that used for hot stamping. Under heat and pressure, the dye crystals sublime (go directly to the vapor phase from the solid phase without melting) and the vapor penetrates the plastic product. As a result, the decoration is very durable and wear resistant. It is also cost competitive against other processes such as two-step injection molding or silk screening. 

Currently, one of the most important applications is the front-end of recent cars such as the Mini Cooper from BMW, Mazda 6, Audi A6, Ford Focus and VW Polo, associating long glass fibre reinforced polypropylene injected onto stamped metal, which leads to weight savings in the range of 30-35% compared to traditional solutions. 

Injection molding is employed to stamp out copies of the master discs from polycarbonate. The molded polycarbonate discs are cooled and hardened quickly, within about 4—6 sec, and evenly. The dye layer is then applied. The applied dyes are often proprietary and continually modified in an attempt to get a better dye. The dye must be compatible with the system and adhere to the polycarbonate base. It is applied by spin coating i.e., the disc is spun and the dye is sprayed onto the surface. The dye is then dried and cured. 

Corrin B. 1963. Aluminum pneumoconiosis II. Effects on the rat lung of intratracheal injections of stamped aluminum powders containing different lubricating agents and of a granular aluminum powder. BrJIndMed 20 268-276. 

Reinforced thermoset (RTS) plastic B-stage sheet material can be processed with its required heating cycle. However the most popular is to use reinforced thermoplastic (RTP) sheets usually using polypropylene plastics. Compared to injection molding RTPs, these stamped products can provide improved mechanical and physical properties with its longer fibers such as impact strength, heat distortion temperature, and much less anisotropy. 

When processing plastics some type of tooling is usually required. Tools include molds, dies, mandrels, jigs, fixtures, punch dies, perforated forms, etc. The terms for tools are virtually synonymous in the sense that they have some type of female and/or negative cavity into or through which a molten plastic moves usually under heat and pressure or they are used in secondary operations such as cutting dies, stamping sheet dies, etc. These tools fabricate or shape products. In this chapter injection molds and extrusion dies are primarily reviewed because they represent over 95% of all tools made for the plastic industry. This chapter also includes information applicable to other molds and dies used in the other processes some of the other chapters too provide information applicable to their tools. 

Lecithin will function as a release agent, providing cleaner and faster pet food or biscuit parting from a stamp or mold. A reduction in the amount of pressure required to create an impression with a stamp is seen when lecithin is used in the mix. The ease of formation of intricate, stamped, surface appearance details, especially with low-fat products, is also improved with lecithins. When dough is being cut, lecithin improves release from the die, especially with rotary cutters. With superior release, foods and biscuits are formed with a better impression, and lower numbers of cripples (i.e., improperly formed product). Some pet biscuits are formed from a batter injected into a mold prior to cooking. Lecithin can improve flowability of the batter so that it fills all the mold corners and cavities. After cooking, lecithin improves release from the mold. 

Fig, 10.24. Simplified schematics illustrating some deposition techniques (a) thermal evaporation (b) stamping (c) liquid-solid interface (d) electro-chemistry set-up (e) Langmuir-Blodgett technique (f) electro-spray deposition (g) pulse injection method (h) solution casting (i) spin-coating. 

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