Chapter 5. Blown Film Dies
		
		
		

		

			
J. Vlachopoulos, R. Castillo, N. Polychronopoulos and S. Tanifuji

			
		
		
		

		

			
Abstract
			     Blown film extrusion is the most important process for the production of plastic films, ranging in thickness from 0.5 mm to as thin as 5 µm according to Butler [1].

			     The polymer is melted in an extruder and the hot melt is pumped through a die to form a thin-walled tube, which is simultaneously axially drawn and radially expanded.

			      In most installations the extruder(s) are horizontal and the blown film bubble is formed vertically upward as shown in Figure 5.1 (from Sidiropoulos [2]). Unlike the cast film process, which is discussed in Section 4.1, the film produced through film blowing can impart different physical properties into the film when the film is stretched both axially and radially. 


		
		
	
		

		

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