Maguire: LineMaster software for film producer
A newly installed yield control system from Maguire has already made possible outstanding product quality and consistency in a three-layer blown film coextrusion line operated by Coextruded Film Technologies [Pty] Ltd. (CFT), according to Bob Boden, managing director of this relatively new producer of polyolefin packaging and industrial films. The yield control system, based on new Maguire (R) LineMaster (TM) software (see accompanying news release), is the latest Maguire technology to be installed in the company’s initial production line, which also includes three Maguire (R) weigh scale blenders (one for each extruder), a Clear-Vu (TM) loader, an LPD (TM) resin dryer, and Maguire (R) Extrusion Control Network (TM) network software.
‘Maguire’s LineMaster system has enabled us to maintain extremely precise layer ratios and to produce rollstock with weights that are virtually identical from one roll to the next,’ said Boden. ‘Our control over layer ratios has resulted in films with consistent heat sealing and mechanical properties-an achievement which has proved invaluable for supplying quality film for high-speed wicketted bag production.’
While Maguire’s Extrusion Control Network controls product thickness by monitoring the weight of raw material metered to the extruder per unit of time and using this data to adjust extruder throughput, LineMaster software provides more advanced control by adjusting both extruder throughput and line speed (length of product per unit of time) to maintain target yield (weight per length of extruded product).
Extrusion Control Enhanced Quality, Saved Material, and Increased Level of Automation
Founded in December of 2000, Coextruded Film Technologies is focused on developing specialized multi-layer polyolefin films. ‘We set up our plant to maximize three capabilities: technological excellence for innovation, quality assurance for customers, and efficient, precision control of all operations by management,’ said Boden. ‘Maguire equipment and systems are at the heart of these capabilities and play a critical role in our current program to institute ISO 9002, EN ISO 14001, and OHSAS 18001. In the meantime, CFT is deliberating the installation of a second, larger three-layer line.’
The current blown film line centers on three 55-mm (2.17-in.) extruders feeding a 300 mm (11.81-in) die and includes oscillating nip, web guide, and tension control. The system is configured to produce film with overall thickness of 10 to 120 microns with three layers of equal thickness. Monthly output is around 70 metric tons (155,000 lb.), according to Boden.
Prior to installing Maguire’s Extrusion Control Network, CFT had set all three extruders to operate at a screw speed of 87 rpm, with the assumption that the three brand-new machines would yield layers of equivalent thickness, according to Chris Crittenden, sales manager of Maguire Europe, which worked with CFT to install Maguire systems. ‘Even at identical screw speeds, however, layer thicknesses differ because of differences in the melt indices and bulk densities of the resins and in conditions inside the extruders,’ said Crittenden. ‘Once CFT installed our Extrusion Control Network and set thickness targets at 33% of overall gauge for each layer, they found that screw speeds now varied from one extruder to another to offset resin and process differences and produce layer thicknesses on-target. This increased control also made possible raw material savings that we estimate roughly at 12%.’
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