04/14/2010

Uniloy Milacron Srl

BLOW-MOLDING PPS FOR TURBO-CHARGED ENGINES (and more about sequential coextrusion)

Blow molding PPS at high temperature (beyond 300 °C) to produce 3D air ducts for the turbo-charged engines requires a special design of the blow molding machines. Uniloy Milacron Srl (Italy) recommend the use of 2 separate extruder+head units (one of them exclusively dedicated to PPS), if the same machine must process other resins (such as PA). The two processing units allow quicker production changeovers without any contamination of PPS with other resins.
Preventing cross contamination – without any long purging procedure at each resin change – is a major benefit when processing expensive engineering resins.
To make the machine set-up even quicker and mistake-proof when changing the mold, Uniloy provide the automatic positioning system of the head. Electric motors – controlled in closed loop through position transducers – move the extruder and head assembly to the right position above the mold, according to pre-set parameters recorded in the mold recipe.
In the last two years Uniloy Italy has introduced other significant innovations for the production of blow-molded air ducts for the automotive industry, such as a new sequential coextrusion head, recently developed by W. Mueller GmbH (Germany). The head – exclusively available for Uniloy Milacron Srl – includes the option for a third layer, and a revolutionary RPV (Radial Thickness Variation) to asymmetrically control the parison thickness (W. Mueller patent).
The Uniloy design of the sequential coextrusion machines maintains the injectors as processing units, but has been improved with a V-shaped layout, to minimize the resin path and get the fastest control on the parison sequence. If compared with other competitors’ technologies, like pre-accumulator chambers (“shot pots”), the injectors feature several major advantages:
• Lower power consumption (shorter resins paths, less components to be heated);
• Shorter purging time and less waste of expensive resins in the production change;
• Lower risk of failures (less components and wiring);
• Easier maintenance (simpler machine layout and better a accessibility);
• Cleaner machine (leakage-proof resin path – unlike “shot pots”, that need some leakage to prevent resin to burn).