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Directional Composites through Manufacturing Innovation

Periodic Reporting for period 2 - DiCoMI (Directional Composites through Manufacturing Innovation)

Reporting period: 2020-03-01 to 2023-12-31

The DiCoMI project’s overall goal was to develop a low-cost hybrid system that will combine the fibre directionality obtained from 5-axis material extrusion with the accuracy obtained from other machining techniques in order to create a truly novel composites manufacturing system capable of producing parts with increased accuracy, reduced cost and enhanced functionality. DiCoMI focused on Directional Fibre-Reinforced Polymers (FRP) materials and combined different manufacturing techniques into a unique and innovative hybrid system.

To develop this innovative hybrid manufacturing system, the following scientific and technical objectives were targeted:

* Objective 1: Define the optimal performances specifications for the DiCoMI system process and materials according to the selected industries' requirements.
* Objective 2: Develop and test a range of polymer/fibre combinations matching pre-defined specifications.
* Objective 3: Design the system with appropriate manufacturing processes parameters.
* Objective 4: Build and test the prototype for specific directional composite/FRP components.

The DiCoMI project had a direct impact on the European and international scientific state of the art in the fields of composite materials and manufacturing equipment, while supporting innovation potential in the automotive and aerospace industries. The outcome was a truly novel prototype composites manufacturing system capable of producing parts with increased accuracy, reduced cost and enhanced functionality.
During the project, the main results achieved were as follows:

WP1 Performance specifications
- Concentrated on medium-performance, continuous fibre reinforced materials, aiming for properties similar to conventional manufacturing.
- Conducted a comprehensive review of conventional and additive manufacturing processes, highlighting the need for improved 5-axis control in additive manufacturing.
- Developed specific KPIs for the DiCoMI process, covering aspects like target applications, materials, system architecture, extruder requirements, and financial considerations.

WP2 Composite materials studies:
- Conducted an extensive review to select a range of existing composite materials, narrowing it down to 11 potential fibres for reinforcement and 7 polymer matrix materials suitable for the DiCoMI system.
- Investigated new polymer/fibre combinations, emphasizing the need for surface treatment of fibres before adding them to the polymer matrix and identifying natural fibres like jute, sisal, and hemp as promising for future development.
- Performed material extrusion tests with various polymer and composite materials, including PLA with carbon fibre reinforcement and a bio-sourced PLA with wood fibre reinforcement, concluding that any material available in filament form could meet the manufacturability requirements of the DiCoMI system.
- Identified carbon fibre (CF) reinforced PLA, PA, and ABS, along with wood fibre reinforced Ingeo PLA as final target materials, although CF-reinforced PEEK emerged as a common choice in aerospace and other industries.
- Tested material specimens made from various composites under tensile and compression conditions, finding that all specimens showed improved mechanical properties compared to pure polymers, especially for CFR polyamide/carbon fibre materials.

WP3 Design of hybrid manufacturing system
- Determined key parameters for additive processing of target materials, including a maximum extrusion temperature of 400°C, platform temperature of 170°C, chamber temperature of 120°C, and nozzle tip diameter ranging from 0.4 to 0.9 mm.
- Identified essential parameters for subtractive processing, including the use of Guhring CR100 dry milling cutters, a spindle speed of 5000 rpm, and a cutter feed rate of 60 mm/s.
- Developed a twin-tool system architecture (extrusion head plus milling cutter) with automated change-over between tools, a single machine configuration, and non-continuous deposition with integrated mechanical cutting of continuous reinforcement fibres.
- Completed the detailed design of the hybrid manufacturing system, which included a new extrusion head design, integration of a rotary table, and exploration of a cost-effective tool changer.
- Demonstrated the system's capability for material extrusion with a range of continuous fibres, surpassing commercial systems in using PLA, PETG, and nylon polymers for continuous fibre fabrication and processing new materials like biodegradable yarns and metallic fibres​.

WP4 Prototyping and demonstration
- Successfully designed, prototyped, and tested the DiCoMI system, focusing on modular design, technical problem-solving, and quality assurance.
- Developed a slicer software using Marlin-based G-code libraries for the MAMEX system, featuring a user-friendly interface for direct input of parameterised CAD parts and machine code generation. The software accommodates continuous strand fibres and has been upgraded to include a rotational print bed.
- Created guidelines for the DiCoMI Material Extrusion (ME) system, which allows 3D layer building with no fixed orientation. The system offers new possibilities in design and material deposition, including controlling extrusion tracks in three dimensions and optimising part strength and stiffness.
- Achieved multi-axis Additive Manufacturing (AM) and fibre deposition through two methods: coating fibres with AM polymers and a dual feed custom AM print head.
- Conducted tests on parts fabricated with continuous fibres, revealing differences in print time and cost among methods. Polymer melt extrusion was the fastest and cheapest, while dual feed fibre and filament were slower and more expensive.

WP5 Project Co-ordination, Management and Dissemination
- Two presentations about the project's results made at MTeM 2023, Cluj-Napoca, Romania.
- Project video published: https://www.youtube.com/watch?v=4Y_l6nmVFyA
- 9 collaborative proposals prepared related to DiCoMI. 5 funded.
Over the whole project, the following progress beyond the state-of-the-art was achieved:

- A method for optimizing process parameters in 3D printing of PLA (Polylactic Acid) components. A new Hybrid Manufacturing Equipment was developed to produce PLA parts using both additive and subtractive techniques. DiCoMI focused on improving surface quality and involved analysing parameters such as spindle rotation, cutting depth, feed rate, layer thickness, nozzle speed, and surface roughness. The researchers developed linear regression and neural network models to predict and improve the surface roughness of manufactured parts.
- Experimental research on 3D printing of composite parts using continuous reinforced fibres in a plastic matrix. The printing process offered advantages like short manufacturing time, high strength, and low part weight. The internal structure of the parts was designed according to load requirements, with continuous fibre placed only in necessary layers. DiCoMI analysed different design possibilities for the internal structure of an industrial part.
- Explored the simulation of piercing composite materials (CFRP) using abrasive water jet (AWJ). The challenge in CFRP processing is to machine internal shapes, holes, or slots without causing delamination. A theoretical simulation using FEA was carried out to study the stresses and deformations during the process.
Partners attending the first DiCoMI meeting
Participants at the MTeM-DiCoMI Conference, at Cluj-Napoca, October 2019
DiCoMI logo