EFFECTS OF EXTRUSION BLOW MOLDING INTERNAL COOLING ...

1.3.5 Efficiency
Fasti USA claims to increase production by reducing air blow cycles by as much
as 35%. The entire forming process for one bottle is 9.51 seconds, with 6
seconds of that being used for blowing of the bottle. If a bottle machine produces
one bottle every 9.51 seconds, that machine will produce 379 bottles in a 1-hour
period. Reducing forming time to 7.42 seconds will allow the machine to produce
485 bottles in 1 hour, a 28% production increase. Production improvements like
this will directly translate into lower costs and higher profits. Savings such as this
could have significant impacts on any industry that uses blow-molding processes.
1.4 Objective
The question that remains is: what effect do the cooler temperatures and
reduced cycle times have on the physical properties of the finished bottle?
1.4.1 Crystallinity
Forming temperatures have a direct relationship with the crystallinity and density
of HDPE containers. Polymer crystallinity and density have a direct correlation
with such properties as clarity, permeability, column crush strength, and impact
strength (Hernandez, Selke, and Culter, 2000). The objective is to quantify what
effect lower processing temperatures will have on bottle performance in these
areas. Table 2 shows the effect of decreased crystallinity on various bottle
properties
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