The cast film process involves the extrusion of polymers melted through a slot or flat die to form a thin, molten film. We typically speak of a film when its thickness is below 1 mm. Thicker materials (> 1 mm) are sheets. These thin plastic membranes are used to separate areas or volumes, to hold items, to act as barriers, or as printable surfaces. As most plastics can be formed into a thin film, the non-exhaustible materials list covers PE, PP, Polyester (e.g. BoPET), Nylon, Polyvinyl chloride, PVC, Polycarbonate and PLA as well as a variety of bioplastics and biodegradable plastics. The use of coextrusion is on the rise, simultaneously extruding multiple materials from a single die to form a multi-layered film. This responds to the need for plastic films offering a performance that cannot be achieved by films composed of a single material.
With rising global population and disposable income, plastic films are finding increasing applications in packaging as well as in non-packaging sectors globally. In packaging, plastic films are used in food, pharmaceuticals, personal care, industrial and other applications. Today, plastic films are extensively used in flexible packaging. In non-packaging, plastic films find applications in agriculture, construction, medical and health care, consumer goods, and others.
Asia-pacific is the key market for plastic films with more than 30% of global market share, fuelled by the rising middle class in China and India. North America and Europe are experiencing slow growth in the sector, with specialty films and biodegradable films slowly gaining importance.
Our CURTAIN integrates our M-Ray technology enabling full-industrial solutions. CURTAINs are tailored to perform a 24/7 industrial measurement task. Each CURTAIN machine consists our innovative Marveloc 602 measuring device. The CURTAIN itself is basically a rigid metal frame that support high measurement reliability and robustness. The rigidity of the frame guarantees robust measurements even in harsh environments. The Marveloc 602 sensors in the CURTAIN system measure through the material, with the transmitter of the sensor positioned above the measured material and the receiver underneath. The M-Ray technology and CURTAIN’s respectable gap height support high measurement standoff, avoiding scratches and defects on the material.
The CUBE solution is a compact module, positioned above the moving material in any production line. It runs reflective basis-weight or thickness measurements from above, so there are hardly any space constraints from underneath. The CUBE measurement system – including state-of-the-art electronics, algorithms and mechanics – is ready for immediate action.
The cooling in the extruded film process is much more efficient than that of blown film. This results in higher production rates with superior optical properties of the product. As the degree of draw and orientation is significantly lower in the cast film process than in the blown film process, the thickness distribution in cross direction is more uniform with cast processes. However, thickness measurement solutions of Hammer-IMS, connected in closed-loop, control the extrusion process to achieve and maintain film thickness variations between 1.5 and 3%.
To support high-width production, plastic cast film manufacturers can decide on the frame length of the Marveloc 602-CURTAIN solution as well as the number of integrated measuring units. The traveling sensors ensure maximum coverage in cross-machine direction. That is the perfect strategy to detect local deviations, which generally correspond to individual screwing bolts of the extrusion die. Thickness measurement in flat film extrusion lines ensures high film quality and reduces the consumption of raw materials.
The M-Ray based measuring solutions of Hammer-IMS offer lower total cost of ownership (TCO) compared to conventional nuclear and radioactive measuring technologies. This is good news for manufacturers with the ambition to equip their production lines with faster and more accurate quality control.
The plastics conversion industry is highly-automated. Check out our technology section on which control loops Hammer-IMS can assist.