Table of Contents
Introduction – Why thermal failure analysis is crucial
Additive manufacturing has established itself as a transformative technology in industrial production – particularly in the development of functional prototypes. It enables the realization of highly complex geometries that would be nearly impossible to produce using conventional manufacturing methods. However, this high degree of design freedom also introduces new challenges in quality assurance: In additive manufacturing, components are built layer by layer, meaning that even the smallest material defects or process deviations can accumulate and compromise the functionality of the final product.
A key quality feature is the thermal behavior of the materials used. Differences in crystallinity, melting behavior or thermal stability have a significant impact on the processability and performance of a material. At the same time, many of these properties are not visible or difficult to detect with mechanical tests alone—especially in powders, copolymers, or polymer blends, such as those used in laser sintering or multi-material 3D printing.
Against this backdrop, thermal analysis is becoming increasingly important—especially differential scanning calorimetry (DSC). It offers the possibility of testing materials for thermal anomalies both before and after the printing process. This not only allows for better evaluation of material quality, but also quantifies the influence of process parameters such as cooling speed or storage conditions.
The aim of this article is to illustrate the practical benefits of DSC for the additive manufacturing of functional prototypes. The focus is less on the technical details of the measurement methodology and more on its contribution to error prevention, material evaluation, and process optimization. The focus is on specific applications, current research results, and their transfer into industrial routines.
Thermal analysis with DSC – fundamentals and potential
Differential Scanning Calorimetry (DSC) is a thermoanalytical technique used to measure the amount of heat absorbed or released by a sample during a programmed temperature cycle. The method is based on comparing the heat flow between the sample under investigation and an inert reference under identical conditions. Whenever a physical or chemical transition occurs in the sample—such as melting, crystallization, or a reaction—the heat flow changes in a measurable way.
By evaluating thermal reactions under defined temperature conditions, material-specific fluctuations, aging effects, or inhomogeneities can be objectively recorded. This enables a reliable assessment of material consistency and allows both storage conditions and manufacturing parameters to be specifically adapted to the respective material behavior.
In practice, this means that a polymeric starting material such as polyamide 12 can exhibit different melting behavior depending on storage or thermal pretreatment, which has a direct impact on component quality. DSC can be used to determine whether the powder is still processable due to thermal degradation, crystallization, or additive changes. At the same time, the method can also be used after the printing process, for example, to examine the homogeneity of structures or to detect undesirable phase transformations.
A particular advantage of DSC is its suitability for comparative analyses: by directly comparing fresh, used, and recycled powders, conclusions can be drawn about material aging, stability, and recyclability. This is particularly relevant for companies that rely on multiple reuse of their materials for cost reasons. Studies such as that by Rüppel et al. (2022) show that thermal parameters can change significantly with repeated use—with a direct impact on print quality.
Another area of application is the targeted development of new material combinations: DSC can provide information on whether blends or copolymers exhibit homogeneous thermal behavior, whether additives are distributed evenly, or whether undesirable side reactions occur. The method thus also acts as a link between material development and process design—a decisive factor in an industrial environment where innovation cycles are becoming ever shorter. DSC measures the difference in heat flow between a sample and a reference as both are heated or cooled in a controlled manner. Any physical or chemical change in the sample causes a measurable change in heat flow (Menczel & Prime, 2009).
These parameters are crucial for additive manufacturing, as they not only determine the energy input and process windows, but also decide whether a material is suitable for certain applications. For example, too low crystallinity can lead to deformation, while too high a melting temperature prevents complete fusion. DSC makes it possible to analyze these properties in the raw material or to check them after the printing process.
In addition, DSC can be used to study the effects of additives or aging processes. This is particularly relevant when recycled powders are reused or new material mixtures are tested. The reusability of polymer powders such as PA12, for example, strongly depends on whether their thermal properties change significantly during the printing process (Rüppel et al., 2022).
Three practical examples of the use of DSC
Metal powder for SLM: Fe-Si alloys
Fe-Si alloys such as Fe-6.5% Si offer high magnetic permeability and low magnetic losses, making them particularly sought after for electrical applications. However, these alloys are very brittle and therefore have limited formability. In the conventional casting process, the possible geometries are limited—a typical example of an application scenario for additive manufacturing. At the same time, due to their physical properties, these materials place special demands on process control in selective laser melting (SLM).
In a study by Gao et al. (2023), the thermal characterization of such alloys was performed using DSC. Among other things, the authors were able to quantify the Curie temperature, the melting enthalpy, and the solid phase transitions. This information was used to draw conclusions about the thermal stability of the alloys during the laser process. The targeted adjustment of the process parameters based on this data made it possible to minimize cracking and texture defects in the final components. This example shows how DSC can serve not only as a diagnostic tool, but also as a tool for process optimization (Gao et al., 2023).
Polyamide 12 in the PBF process
Polyamide 12 (PA12) is the most widely used polymer in the Powder Bed Fusion (PBF) process, especially in laser sintering. The quality of the resulting components depends largely on the thermal process control—more specifically, on the so-called “sintering window.” This describes the temperature range between the start of the crystallization process and complete melting. Only when the powder is within the stable sintering window can dense and dimensionally stable components be produced.
Rüppel et al. (2022) used DSC to show that the thermal properties of PA12 are sensitive to external influences. They were able to demonstrate that storage duration, moisture absorption, and thermal preloading lead to significant shifts in the sintering window. These changes have a direct impact on process reliability and the dimensional accuracy of printed structures. The study made it possible to define criteria for the reuse of powders and establish limits for permissible aging—a decisive contribution to the sustainable use of materials in an industrial context.
Aluminum alloys in additive casting production
DSC is also highly relevant for metallic materials outside of laser melting. One example is the investigation of aluminum alloys such as EN AB-42000, which are used in hybrid manufacturing processes. These are casting processes in which additively manufactured sand cores or casting molds are used to create complex geometries.
Schwienheer et al. (2023) investigated the targeted heat treatment of this alloy to improve its mechanical properties. DSC was used to determine characteristic transformation temperatures and phase changes, which were then used as the basis for customized heat treatment cycles. The result was a significant increase in ductility while maintaining strength—a typical trade-off in foundry engineering that was specifically resolved thanks to DSC measurement data. This application illustrates that thermal analysis can be crucial not only for additive manufacturing itself, but also for downstream process steps such as heat treatment and final testing.
Quality assurance and implementation in industry
The industrial use of Differential Scanning Calorimetry (DSC) for quality assurance in additive manufacturing is becoming increasingly important. While the process was originally used primarily in research and development, it is now also establishing itself in production-related processes. The added value lies not only in the precise characterization of materials, but above all in the ability to detect thermally induced deviations in the manufacturing process at an early stage and take targeted countermeasures.
One key area of application is incoming goods inspection. Even before the printing process begins, a standardized DSC analysis can be used to determine whether a batch of material meets the required thermal specifications. This is particularly important for hygroscopic polymers such as PA12, as even slight deviations in residual moisture or crystallinity can affect printing behavior. By analyzing melting and crystallization behavior, such material deviations can be clearly identified – long before they become visible in the component.
Another area of application is process validation. Here, the DSC is used to examine test specimens or reference samples taken from the production process for thermal consistency. This allows manufacturers to determine whether the actual printing conditions (e.g., laser power, exposure time, or cooling rates) match the planned parameters. This additional control is a valuable contribution to risk minimization, especially in safety-critical industries such as aerospace and medical technology.
DSC also provides valuable insights into the recycling of powder materials. Additive manufacturing processes such as laser sintering generally allow for the multiple use of unsintered powder. However, each reuse changes the thermal properties of the material—for example, through aging, thermal damage, or additive loss. DSC can objectively record such changes and indicate when a material loses its usability. Rüppel et al. (2022), for example, documented a shift in the crystallization range of PA12 after several recycling cycles, which had a direct impact on the dimensional stability and density of the components.
In addition, DSC is used in the qualification of new materials or material mixtures. In industrial innovation projects where new types of powders, additives, or polymer blends are being tested, thermal analysis is an indispensable tool for assessing processability. Companies use it, for example, to check whether the mixture components are thermally compatible or whether homogeneous distribution in the process is realistically achievable. Thermally induced reactions such as unwanted pre-crosslinking can also be quickly identified and quantified using DSC.
One aspect that should not be underestimated is traceability and documentation: In many regulated industries, there is a growing demand for quality assurance to not only take place, but also to be systematically documented and validated. The evaluation of DSC data can be integrated into digital test reports and quality assurance systems. This facilitates audits, traceability, and continuous process improvement.
Overall, it is clear that implementing DSC in industrial practice is not purely an academic approach, but rather an economically and qualitatively worthwhile investment. It offers companies an additional level of control that helps to limit sources of error, increase process reliability, and ensure product quality in the long term. The industrial implementation of DSC measurements usually takes the form of standardized test protocols. DSC is particularly useful in incoming goods inspections, the qualification of new material batches, and the validation of process parameters. In practice, this means that a DSC measurement not only provides information about the suitability of a powder, but also about whether it can be reliably processed in the planned printing strategy.
DSC also plays an important role in research into the recycling of materials. For example, research is being conducted on PA12 to determine how the degree of crystallinity changes with repeated reuse and whether this leads to a change in the mechanical properties of the components (Rüppel et al., 2022). This information helps companies make informed decisions about the use of materials and avoid quality losses in reused materials.
Conclusion and overview
The examples presented here impressively demonstrate that Differential Scanning Calorimetry (DSC) is a versatile tool for quality assurance and process control in additive manufacturing. Particularly in the development and testing of functional prototypes, it enables the early identification of potential sources of error—whether in material selection, the printing process itself, or post-treatment.
The ability of DSC to provide precise information about melting behavior, crystallinity, and thermal stability opens up a wide range of applications: from incoming goods inspection and process optimization to material development. Companies that systematically use thermal analysis benefit from improved reproducibility, higher material efficiency, and reduced scrap rates. In regulated industries with high traceability requirements—such as medical technology or aviation—DSC also provides documentable proof of the thermal quality of the materials used.
At the same time, the method also offers great potential in research: interdisciplinary projects, such as the development of novel polymer blends or the investigation of alternative recycling strategies, benefit from precise thermal characterization. DSC is also gaining importance in the context of the circular economy, as it helps to objectively evaluate the reusability of powders.
A promising outlook lies in the automation and digitization of data evaluation. Modern evaluation algorithms—based on machine learning, for example—can recognize patterns in thermal measurement data, predict anomalies, or automatically adjust process parameters. This could enable DSC to be integrated even more closely into the industrial process chain in the future—possibly even as part of digital twins or predictive quality assurance systems.
Overall, anyone who wants to use additive manufacturing not only for geometry optimization but also for functional integration and process reliability will find it almost impossible to do without precise thermal analysis. DSC is a key process in this regard—small in terms of equipment, but big in terms of its influence on quality, innovation, and cost-effectiveness.
Selected Literature for Further Reading
- Gao, J., Zhang, H., Liu, S., et al. (2023).
Thermal behaviour and microstructure of Fe–Si alloy fabricated by selective laser melting. Materials Characterization, 194, 112520.
https://doi.org/10.1016/j.matchar.2022.112520 - Menczel, J. D., & Prime, R. B. (Eds.). (2009).
Thermal Analysis of Polymers: Fundamentals and Applications. John Wiley & Sons.
https://doi.org/10.1002/9780470423837 - Rüppel, A., Dobner, K., Schild, A., et al. (2022).
Influence of repeated reuse on the thermal and physical properties of PA12 powder for laser sintering. Polymers, 14(15), 3120.
https://doi.org/10.3390/polym14153120 - Schwienheer, C., Bente, K., Buhl, J., et al. (2023).
Heat treatment strategies for additive–cast hybrid aluminum components: Influence on microstructure and mechanical properties. Materials & Design, 230, 111946.
https://doi.org/10.1016/j.matdes.2023.111946
