Fabricating processes secondary operations

Material selection process must also address processing considerations such as type of fabrication process, secondary operations, and component assembly. 

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. 

Experimental expander vanes are being fabricated to potentially qualify a unique powder metallurgy process that provides net shape, finish, and hardness without secondary operations. 

The development of an alternative fabrication technique that would solve these issues would have commercial benefits. Researchers have demonstrated that embossing techniques offer solutions to many of the previously detailed problems [3]. Localized heating coupled with embossing has been demonstrated by many researchers to fabricate micro-features on thermoplastic substrates. However, this process produces undesired flash which must be removed with costly secondary operations [4]. Because the substrate is only locally heated, the material that is displaced during the embossing caimot be captured by the embossing tool to form a flat surface. It is possible to heat the entire surface of the substrate and reform the flash to a flat surface, but this is not desirable because it increases the heat input. 

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