Co-Rotating Twin-Screw Technology, Process Engineering and the Value of Working Together

Engineering Built Around the Process

For decades, ICMA San Giorgio has developed and manufactured co-rotating twin-screw extruders and complete processing lines for demanding applications in the plastics industry.

The company’s activity has evolved around a simple principle: an extruder is only one part of a successful industrial process. The characteristics of the polymer, the formulation, the feeding behaviour, the required mixing intensity, devolatilization, downstream operations and final product specifications all influence the design of a line.

For this reason, ICMA combines machine manufacturing with process engineering and plant engineering. Its experience covers conventional and highly engineered compounds, filled and reinforced materials, reactive extrusion, biopolymers, direct extrusion and, increasingly, advanced mechanical recycling.
This broad application base is particularly relevant today, as processors are being asked to handle more complex raw materials while improving product quality, energy efficiency and sustainability.

Co-Rotating Twin-Screw Extrusion at the Core

At the centre of ICMA’s technology are high-torque co-rotating twin-screw extruders.

Their modular architecture makes it possible to manage the main operations involved in polymer processing within a controlled and flexible system: feeding, melting, distributive and dispersive mixing, incorporation of fillers and additives, devolatilization and melt conditioning.

Rather than treating the extruder as a standard machine, ICMA develops the processing section around the application. Screw configuration, L/D ratio, feeding systems, thermal profile, degassing sections, filtration, downstream equipment and process control are defined according to the material and the required result.

This approach becomes especially important with difficult formulations or variable feedstocks, where the performance of the complete line depends on the interaction between several processing stages rather than on any single machine parameter.

From Extruders to Turnkey Plants

ICMA’s scope can extend from the extrusion section to complete turnkey plants.

For a customer developing a new production unit or expanding an existing operation, this can include raw-material handling and dosing, extrusion, pelletizing or direct extrusion, automation, downstream equipment and the integration of the complete process.

Turnkey engineering is particularly useful when a company is entering a new market, industrializing a new formulation or introducing a process that cannot simply be transferred from an existing standard line.
In these projects, ICMA’s role is to connect process requirements with mechanical and plant engineering, keeping responsibility for the interaction between the different parts of the system.

The objective is to design the plant around the material and the required product rather than adapt the process to a predefined equipment package.

The People Behind Technology

Technology alone does not determine the outcome of a complex extrusion project. The quality of the interaction between the customer and the engineering team is often equally important.

ICMA brings together process engineers, mechanical and automation specialists, project managers, commissioning technicians and experienced production personnel who remain closely involved throughout the development of a project.

Technical competence is combined with relatively short communication lines, rapid response and a pragmatic approach to problem solving. This is particularly valuable during process definition, testing, commissioning and start-up, when decisions frequently need to be made quickly and with a clear understanding of both the material and the equipment.

The result is a working relationship in which customers can interact directly with the specialists responsible for the process and the machine. This continuity from initial discussion through industrial implementation is an important part of ICMA’s engineering culture.

From Process Development to Industrial Validation

Process development has long been part of ICMA’s approach to engineering. The company’s Innovation Hub provides industrial-scale equipment where customers can work with ICMA engineers on real materials and applications before defining the final production solution.

The facility is not dedicated to one technology or market. It supports ICMA’s principal fields of activity, including advanced compounding, direct extrusion and mechanical recycling, as well as the development and validation of newer process concepts.

Industrial-scale testing is important because extrusion performance cannot always be predicted from laboratory data alone. Feeding behaviour, mixing efficiency, devolatilization, filtration, melt stability and final product properties are strongly influenced by the characteristics of the actual material and by the interaction between process stages.

Working with representative materials on industrial equipment allows process assumptions to be verified, operating windows to be identified and different configurations to be compared on the basis of measured results. The same environment also allows customer and supplier engineering teams to work together before the project moves to industrial scale.

For ICMA, the Innovation Hub therefore has a dual role: it is a facility for technology development and an engineering tool for reducing uncertainty when defining a new industrial process.

Sustainability Is Changing the Extrusion Challenge

The transition towards a circular plastics economy is creating a new generation of processing requirements.

Recycled feedstocks are inherently more variable than virgin polymers. Flexible films may have extremely low bulk density and be difficult to feed consistently. Post-consumer materials may also contain moisture, volatile substances, inks, organic residues and other contaminants that affect odor, melt quality and final properties.

At the same time, the objective of recycling is gradually moving beyond the simple conversion of waste into pellets. In many applications, processors need recycled materials with greater consistency and higher technical value, capable of returning to more demanding uses.

This shift brings recycling closer to the disciplines traditionally associated with compounding: controlled feeding, mixing, devolatilization, purification and material modification.

ReCoPurTech™: Applying Compounding Know-How to Advanced Recycling

One recent example of this development philosophy is ReCoPurTech™, ICMA’s technology platform for advanced mechanical recycling and up-cycling.

The project applies expertise developed in co-rotating twin-screw compounding to some of the more demanding issues in plastics recycling: efficient feeding, intensive devolatilization, melt purification and, where required, re-compounding of the recycled polymer.

The platform has been conceived for a broad range of feedstocks rather than a single waste category. These range from very low-bulk-density flexible materials to rigid HDPE and PP flakes and regrind with bulk densities above 0.4 g/cm³. Proprietary developments such as Boost-Feeder™ address the feeding of particularly light materials, while different extrusion and purification architectures can be selected according to the characteristics of the waste stream and the required final material.

ReCoPurTech™ can be configured around a single co-rotating extruder or, for more demanding purification and up-cycling applications, around a cascade arrangement. In the latter case, ICMA’s compounding experience becomes part of the recycling process itself, allowing recycled polymers to be modified and engineered for subsequent applications.

As with other ICMA processes, ReCoPurTech™ can be investigated at the Innovation Hub using customer materials and industrial-scale equipment, allowing the most relevant process parameters to be assessed before an industrial configuration is defined.

A Common Engineering Approach Across Different Applications

Although compounding, direct extrusion and recycling address different markets, they share many of the same engineering questions: how a material is fed, how it behaves inside the extruder, how energy is transferred, how volatiles are removed and how the required properties are obtained consistently at industrial output.

This common technological foundation allows knowledge developed in one field to contribute to another. Experience in high-filler compounding can inform difficult feeding applications; devolatilization know-how developed for reactive or sensitive formulations can support recycling projects; direct extrusion experience can help simplify production routes by eliminating intermediate processing steps.

ICMA’s development model is therefore based less on isolated product families and more on the continuous transfer of process knowledge across applications.

Looking Ahead

The plastics industry is being asked to reconcile performance, cost and sustainability at a time when raw materials and regulatory requirements are becoming more complex.

In this environment, equipment alone is not sufficient. Industrial projects increasingly require a combination of flexible extrusion technology, process understanding, the ability to validate concepts on real materials and an engineering team capable of responding quickly as the project develops.

ICMA San Giorgio continues to build its activity around these elements. High-torque co-rotating twin-screw extrusion remains the technological core, while process engineering, turnkey plant capability, industrial testing and the experience of the people behind each project extend that technology into complete production solutions.

Developments such as ReCoPurTech™ illustrate how this established competence can be applied to new challenges in circular plastics, while the same engineering approach continues to support advanced compounding and direct extrusion applications.

The underlying objective remains consistent: to turn process knowledge into reliable industrial solutions and to make the development of complex extrusion projects as straightforward and technically sound as possible.

ICMA San Giorgio