Bio-based filaments: Almond PLA is born

In the Crea3D laboratories, innovation is combined with sustainability, and the experimentation on new materials for 3D printing is one of the key topics to focus on. In this perspective, a project was born that combines biotechnology, circular economy and additive manufacturing: the creation of a composite PLA filament, obtained by reinforcing the polymer matrix with powder derived from almond shells, a commonly available but undervalued agri-food waste.

The aim of this research is twofold: on the one hand, to study the technical and mechanical potential of a bio-based composite material; on the other hand, to concretely demonstrate how a circular approach can also be applied in the 3D printing sector, contributing to reduce the environmental impact of plastic materialsthe commonly used ones.

The project was conducted within a curricular internship in collaboration with the Polytechnic of Bari, who will take care of the performance tests, involving a student from the course Mechanical Engineering, who actively participated in all phases of the experimentation, from the preparation of the raw materials to the mechanical characterization of the printed specimens.

The choice to use agri-food waste as reinforcement for polymeric materials arises from a broader reflection on the circular economy and the need for reduce the use of virgin raw materials. I almond shells, normally considered agricultural waste, actually represent an interesting resource for their fibrous structure and the ease with which they can be transformed into powders compatible with thermoplastic matrices such as PLA. The objective is not only technical, but also ethical: to create materials with a lower environmental footprint, capable of responding to application needs without compromising the process sustainability productive.

One of the key elements of the project is the use of a extruder of the brand 3devo, an advanced platform for the production of experimental filaments. This tool has proven to be instrumental in ensuring the quality, repeatability and precision required in a research and development context.

The experimental workflow

To ensure the reproducibility and validity of the results, a detailed and methodical workflow was defined, which included the following steps:

1. Natural fiber preparation
The almond shells were initially subjected to a mechanical crushing phase, followed by fine grinding. The resulting material was then sieved with a calibrated mesh to obtain a powder with a particle size of less than 0.4 mm, a value chosen to optimize compatibility with PLA during extrusion and reduce the risk of clogging.

2. Drying and mixing
To avoid degradation or bubbles during extrusion, both the PLA pellets and the almond fiber were dried at a controlled temperature. The mixture was prepared in a proportion of 95% PLA – 5% fiber, dosing the materials with precision scales and mixing them uniformly before loading into the hopper.

3. Extrusion
The extrusion of the composite filament required careful calibration of the parameters. Thanks to the four independent heating zones, it was possible to set a gradual and specific thermal profile for the mixture. Real-time monitoring of the diameter ensured the production of a constant 1.75 mm filament, a fundamental parameter for FDM printing. The dedicated software allowed to record detailed data on temperatures, screw speed and process stability, offering valuable support for any future iterations.

4. Process optimization and stabilization
During the first tests, difficulties in homogeneously dispersing the fiber inside the polymer matrix were highlighted, with consequent fluctuations in the diameter of the filament. Through subsequent optimizations – both in the mixing phase and in the temperature regulation – it was possible to obtain a stable product, ready for printing.

5. Quality controls on the filament
The resulting filament was subjected to dimensional checks with a digital caliper and a visual analysis to evaluate the homogeneity of the fiber distribution. Once validated, it was used to print standardized specimens for mechanical tests.

The key element of the experimentation: the 3devo extruders

The success of this experimental activity was also made possible thanks to the use of a 3devo extruder, a compact but highly professional machine, specifically designed for the production and development of custom filaments. Its advanced configuration makes it an ideal tool for research and development activities, both in academic and industrial fields.

Among its main features are:

• Four independent heating zones, which allow precise and modular control of the thermal profile along the screw. This is essential when working with composite materials, where gradual and uniform melting of the polymer and filler must be ensured.
• Real-time monitoring of filament diameter, with dynamic adjustment to constantly maintain the desired size (1.75 mm in our case). This ensures high extrusion quality, avoiding waste and simplifying the subsequent printing phase.
• Proprietary software for data acquisition, which allows you to view, record and analyze key parameters such as temperature, screw speed, pressure and diameter consistency. This feature is particularly useful in the experimental field, where data traceability is essential for process optimization and reproducibility.
• Customizable presets for each material, which make it easy to switch from one formulation to another and allow optimal conditions to be replicated in future tests.

During our testing, the extruder demonstrated great reliability, precision and versatility, facilitating every stage of filament production. Even in the presence of unconventional materials, such as almond shell-derived fiber, the system responded well to adjustments, supporting both the initial exploration phase and the final optimization.

For laboratories, universities, startups or companies that wish to develop innovative materials, 3devo extruders represent one strategic tool: compact but professional, simple to use but highly configurable, designed for those who do real experimentation and want to quickly move from concept to prototype.

Considerations on the results

At the time of writing this case study, the process has reached a key milestone: the production of standardized specimens for mechanical tests, which will be performed at a later stage. Tensile tests and quantitative analyses will allow to objectively evaluate the actual contribution of almond fiber to the mechanical properties of PLA, but such data are not yet available.

Despite this, some qualitative observations on the filament already obtained allow us to draw interesting preliminary considerations. The material presents a good dimensional stability during printing and showed no clogging issues or irregularities in flow. Additionally, the filament surface finish, slightly rough and warm to the touch, is reminiscent in some ways of natural wood, giving the printed pieces a distinctive aesthetic appearance.

This feature opens up possible applications in the field of sustainable design and household items, where thevisual and sensorial aspect of the material can represent an added value. Even in the absence of mechanical performance superior to virgin PLA, the filament reinforced with almond powder could in fact justify its use in projects that favor aesthetics, tactility and low environmental impact.

Conclusions and future developments

This experiment has demonstrated the technical feasibility and the scientific value of using agro-food waste as a reinforcement for biodegradable polymers in 3D printing. The 3devo extruder played a central role, providing the control and flexibility needed to develop new materials with a high degree of precision.

The project represents a first step towards the creation of custom bio-composite filaments, where sustainability is not a limitation but an opportunity. The next phases of the research will include:

• The exploration of different load percentages of fiber to optimize mechanical properties.
• The use of other organic waste (such as fruit stones, rice husks or coffee grounds) as alternative fillers.
• A comparative analysis of theenvironmental impact throughout the entire life cycle of the material.

Thanks to the synergy between advanced technology, university research and attention to sustainability, we believe that projects like this can form the basis for a new generation of 3D printing materials: greener and equally high-performance.