Linking culture and conservation in the Caura River Basin

Initial Success With Small Production Run of Tanks

Thursday, November 3, 2011
Removing the extrusion die from the blow molding machine.
Off-center machining to ovalize the extrusion die.
First tank run.

Maracay, Venezuela. Caura Futures’ innovative fuel tank has finally seen the light of day. Its design challenged the blow molding shop due to the tank’s unique nesting shape. In the blow molding process, a hot-extruded high density polyethylene (HDPE) sleeve is pinched off inside the mold and expanded forcefully with a burst of pressurized air. In tests using our mold, the corners of the blown tank were too thin. To correct this problem, the extrusion die had to be ovalized, which resulted in more material reaching the corners. This required a trial-and-error process, using a felt pen to determine where to modify the die by registering where marks on the extruded plastic finished on the blown tank. Then, off-center mounting in a large lathe enabled its operator to make subtle scoops in the die. This process worked to help homogenize wall thickness and then the overall tank weight was increased to produce a durable container. The next step is field testing with water.