Extrusion 8-2016

58 Review Extrusion 8/2016 each profile. During the suction process the parison tends to twist in the mould cavity, depending on the cavity shape and on some process parameters. This type of parison rotation (which is not vi- sible, because the parison is fed into the cavity when the mould is already closed) can jeopardize the specific radial varia- tions of the parison thickness that are in- tentionally generated during extrusion to compensate for the different stretch ra- tios during the blowing process – unless it can be accurately predicted and taken into account in the radial profiling of the parison. In order to measure the twisting behaviour of the parison in a specific mould and adjust the radial profile ac- cordingly, it has been a common practice to spray white paint on one side of the parison during extrusion to create a white line: the position of this white line on the blow moulded item identifies the rotation that has occurred in each sec- tion of the parison. Extending the limits of parison mark- ing: new possibilities with “W-Print” : The new “W-Print” takes advantage of the sharp definition of the marking dots and offers the possibility of printing cha- racters and text directly on the parison during extrusion. This function opens a wide array of new possibilities to tune n Among the world leaders of blow moulding machinery manufacturers, ST Soffiaggio Tecnica has earned a recog- nized position of excellence in parison suction technology. The ASPI series of machines has been the market bench- mark for the past ten years, to such an extent that today the name “ASPI” is synonymous with “parison suction” technology. The parison suction process is a tech- nique of efficiently manufacturing con- voluted 3D ducts: no seam lines, en- hanced wall thickness uniformity and mi- nimum energy consumption. This tech- nique has proven to be extremely effi- cient for the production of ducts for the air induction systems of turbocharged engines for cars and trucks. As a world leader in this technology, ST Soffiaggio Tecnica has been continuously improving the performances of its ASPI machines and developing new features to achieve better quality of the blow moulded parts, more efficient produc- tion and easier machine operation and maintenance. Other specific features introduced for the first time on this ASPI 150.3 model – such as the Parison Diameter Monitoring and the Production Data Report acces- sible from remote devices via ST App – make the new ST Soffiaggio Tecnica ma- chines ready for Industry 4.0. At K 2016 ST Soffiaggio Tecnica exhibi- ted the new ASPI 150.3 machine – the third release of the best-selling model of parison suction machines. Compared with the previous version ASPI 150.2, the new model offers larger platens (900mm wide, 1100mm high) to accommodate moulds up to 1650mm long. The ma- chine is equipped with a new HMI based on a 21,5” full HD multi-touch screen that integrates all machine functions in a new job-oriented and context-sensitive navigation concept. The operators can log-in simply and quickly through a per- sonal RFID card instead of inputting al- phanumeric codes. The job-oriented na- vigation concept works on configurable profiles (production/tool-setting/mainte- nance/ quality control) for mistake-proof access to the functions of interest for Pace towards Blow Moulding Factory 4.0 the process (marking the point number instead of just a dot), in the quality con- trol (marking the type of inspection to be performed at that point), and in produc- tion traceability (marking the date and time of manufacture). A ghost ink is also available, if the mar- ked characters must be visible only to in- tended operators when illuminated by a UV lamp. In-line Parison Diameter Monitoring (patent pending) : The “swell factor” measures the tendency of the parison diameter to exceed the head tool diame- ter due of a variety of factors: plastic re- sin type, head tool profile, push-out speed, and others. It is a very important parameter in any extrusion blow mould- ing process, and it may become critical in the parison suction process. Measuring the parison diameter at every cycle and monitoring the swell factor is now possible on the new ASPI 150.3 ma- chine. Once the process has been accu- rately optimized for a certain mould, the parison diameter can be recorded in the recipe and used by the SPC (Statistical Process Control) as a parameter for the evaluation of the process stability and production repeatability. If the diameter, measured at every cycle, exceeds the lower or the upper set limit in the tole- S.T. Soffiaggio Tecnica booth at this years K-show (Photo: S.T. Soffiaggio Tecnica)