Everything you need to know about extrusion lines
When we use plastic objects, pipes, cables, or packaging in our daily lives, we rarely think about how they are produced. Yet, behind the precise and continuous shape of these elements, there is often a single technology: extrusion.
What is an extrusion line
An extrusion line is an industrial system designed to transform thermoplastic, elastomeric, or metallic materials into a continuous product by pushing the molten (or plasticized) material through a shaped die. The entire process operates in a continuous and controlled manner, allowing adjustment of temperature, pressure, throughput, haul-off speed, and dimensional stability of the final product, thus ensuring geometric accuracy and consistent quality.
Configurations may vary: single-screw extruders for standard production, co-rotating twin-screw extruders for complex mixes and compounding, counter-rotating twin-screws for rigid PVC, flat dies for sheet production, or blown film systems for bubble film manufacturing.
Main components of the extrusion line
Every extrusion line is made up of essential components working in synergy.
The feeding section includes the hopper, gravimetric or volumetric dosing systems, and dehumidification units—crucial for moisture-sensitive materials such as PET, PA, or PC. Many plants also include metal detectors and filters to eliminate possible contaminants.
The extruder is the heart of the line. Inside the heated barrel, the screw divides the process into three main zones: feeding, compression, and metering. In these sections, melting, homogenization, and pressurization of the polymer occur before it enters the die. Sensors and thermoregulation systems ensure stable temperature and pressure.
The die gives the material its final cross-section. Its internal geometry is engineered considering the polymer’s rheology and the shrinkage occurring after cooling. There are annular dies for pipes and sheaths, flat dies for sheets and film, crosshead dies for cable coatings, and multilayer dies for co-extrusion.
After shaping, the product undergoes calibration and cooling. Thermoplastic profiles typically use vacuum calibration tanks and water-cooling baths; blown films use a cooling tower and air ring; sheets rely on cooled calender rolls. This phase stabilizes the product’s geometry, preventing deformation or ovalization.
The haul-off unit synchronizes the product’s speed with the extruder. Finally, the product is cut or wound using rotary saws, guillotines, or automatic winders.
The extrusion process
The cycle begins as the material enters the hopper. As it progresses through the screw, the polymer heats up through a combination of external heating and friction. Once melted, it becomes homogenized and pressurized until reaching the die, where it takes on the designed shape.
Immediately after leaving the die, the material is still plastic. It is therefore calibrated and cooled right away to stabilize its dimensions and mechanical properties. The haul-off unit ensures a constant speed, essential for maintaining tight tolerances. The finished product is then cut or wound, depending on whether it is a profile, pipe, or film.
Technical examples of products obtained by extrusion
Pipes and conduits
Polyethylene (PE100), polypropylene (PP-H, PP-R), or PVC-U pipes are extruded through annular dies and stabilized in cooling baths. Controlling ovality and wall thickness is crucial, especially for pressure pipes used to transport water or gas. Inline laser measurement systems ensure dimensional consistency.
Technical profiles in PVC, ABS, PC, or TPE
Profiles for window frames, automotive seals, thermal spacers, and furniture components are produced using single- or twin-screw extruders, depending on the material. Their accuracy depends on proper die temperature and vacuum calibration. Co-extrusion makes it possible to combine rigid and flexible materials into one functional profile.
Sheets and panels produced with flat dies
The production of PET, PC, PP, or PVC sheets uses flat dies combined with cooled calender rolls. The main challenge is ensuring uniform thickness, achieved by adjusting flow distribution in the die and precisely controlling roll temperature.
Blown film and cast film
Films are produced in two ways:
- Blown film: the molten material forms an air-inflated bubble that is cooled and then flattened.
- Cast film: the molten polymer exits a flat die and is immediately cooled on highly polished rolls.
The blow-up ratio (BUR), micrometric thickness, and cooling symmetry are critical parameters.
Quality control
Quality control in extrusion involves inline dimensional checks using laser systems, thickness analysis, monitoring of extruder pressures, and mechanical tests such as tensile and impact resistance. For plastic materials, thermal analyses (DSC, TGA) and color consistency checks using spectrophotometry ensure compliance with technical specifications.
A complete extrusion line is a complex system where material rheology, die design, thermal management, and speed control work together to produce a continuous and technically reliable product. Thanks to the flexibility of the process, it is possible to manufacture pipes, profiles, sheets, multilayer films, and metal structures with very tight tolerances and specific functional characteristics.
Omipa: a benchmark in extrusion line technology
In the world of extrusion technology, Omipa stands as one of the most historic and innovative companies in the sector.
Founded in 1963 as a small mechanical workshop producing accessories for plastics processing—such as extrusion dies, calendering systems, and auxiliary equipment—the company quickly expanded into the design and construction of complete extrusion lines for the production of sheets, film, foils, and hollow profiles in various thermoplastic materials.
Over more than 60 years, Omipa has grown from a local workshop into an international company renowned for the precision, reliability, and high quality of its extrusion lines.
Today, Omipa develops highly specialized extrusion lines for:
Applications: building and construction, roofing for large infrastructures, agricultural greenhouses, natural lighting systems, wall panels, interior design panels.
Applications: packaging, advertising and visual communication, pharmaceutical applications, automotive components, home appliances, agricultural applications, building industry.
Applications: food packaging, thermoformed products, display and retail advertising, stationery items.
Applications: displays, lighting, graphics, advertising, construction, safety barriers, interior design and furniture.
• High Quality Technical & Thermoforming Sheet
Applications: automotive, furniture and home appliances, sanitary equipment (bathtubs, showers), interior design.
Thanks to fully in-house manufacturing, every phase—from design to production—is under direct control, ensuring machines that combine efficiency, performance, and long-term durability.
Another key strength is the high level of customization: Omipa designs tailored solutions to meet specific production needs, integrating new technologies, advanced automation systems, energy-efficient configurations, and the ability to process both virgin and recycled materials.
Flexibility and uncompromising quality are our core values. By choosing Omipa, you’re investing not just in machinery, but in a guarantee of excellence and reliability without compromise.
