Stamps, perforation

A variation of the normal sieve tray is the Turbogrid tray developed by the Shell Development Company. The Turbogrid tray uses slots instead of circular holes and operates as a counterflow plate unit with no downcomers. A typical tray consists of a flat grid of parallel slots. The slots can be stamped perforations in a flat metal sheet or the open spaces between parallel bars. 

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. 

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. 

In other materials, like paper, perforations are used to efficiently separate portions of paper (like the postcards, paper dolls, and original perforated stamps) from a larger piece, without the use of scissors. 

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