Modern Alternatives to Injection Molding

Plastics processing is one of the key technologies in numerous industries – from medical technology to automotive to packaging. For a long time, injection molding was considered the standard for the serial production of thermoplastic molded parts: precise, fast, and economically scalable. However, increasing demands for customization, sustainability, and shorter development times are ensuring that new processes are becoming increasingly important. Modern alternatives such as additive manufacturing, thermoforming, or powder sintering enable new degrees of freedom in design and production – and open up potential for more flexible, resource-efficient processes. In many applications, they are thus emerging as a serious complement to, or even replacement for, traditional injection molding.

Additive Manufacturing: Flexibility at the Push of a Button

Additive manufacturing – especially 3D printing with plastics – is at the forefront. Processes such as fused deposition modeling (FDM), stereolithography (SLA), and selective laser sintering (SLS) enable the layer-by-layer production of complex geometries without costly tooling. 3D printing offers immense advantages, particularly in prototyping, medical technology, and small-batch production: customization, short setup times, and minimal material waste.

One current disadvantage is limited production speed and capacity. Furthermore, the choice of materials is limited compared to traditional thermoplastics, although significant progress is being made in this area – for example, with high-performance plastics such as PEEK or PA12.

Thermoforming and Deep Drawing: Cost-Efficiency for Medium Batch Sizes

Another established process is thermoforming, in which heated plastic sheets are drawn over a negative mold. This process is ideal for large-area components with simple geometries, for example, in aviation or vehicle interiors. It scores points with low tooling costs and comparatively fast production – but with limited detail fidelity and design freedom.

Powder Sintering (SLS, MJF): Complexity without Tools

Selective Laser Sintering (SLS) and Multi Jet Fusion (MJF) are among the powder-based additive manufacturing processes. They enable the tool-free production of mechanically resilient components with high dimensional accuracy. In industrial applications, they are increasingly replacing machining processes and offer enormous design freedom, especially for complex, functional parts.

Integration into existing production lines

The greatest challenge of modern processes lies in system integration. While traditional injection molding systems are designed for high volumes, modern processes offer advantages in customization and early development phases. A hybrid production approach can be the solution here: Prototypes and pre-series production are manufactured additively, while validated designs are scaled up in injection molding.

Digital process chains (keyword: digital thread) and CAD-CAM links play a central role in the integration of new manufacturing technologies. Furthermore, modern MES (Manufacturing Execution Systems) systems offer options for cross-process control and quality control.

Sustainability and Resource Efficiency

Modern processes also offer potential in terms of sustainability: Additive processes reduce waste, enable more local production, and contribute to reducing storage and transport costs through on-demand manufacturing. At the same time, intensive work is being done on biodegradable or recyclable materials, such as PLA or PETG with recycled content.

Conclusion

Plastics processing is at a turning point. Traditional injection molding processes remain irreplaceable in mass production, but modern alternatives such as 3D printing, thermoforming, or powder sintering open up new avenues for greater flexibility, sustainability, and innovation. A well-thought-out combination of established and new processes is the key to future-proof manufacturing.

Sources and Literature

1. Ngo, T. D., Kashani, A., Imbalzano, G., Nguyen, K. T. Q., & Hui, D. (2018). Additive manufacturing (3D printing): A review of materials, methods, applications and challenges. Composites Part B: Engineering, 143, 172–196. DOI: 10.1016/j.compositesb.2018.02.012

2. Michaeli, W., & Hopmann, C. (2013). Thermoformen – Grundlagen, Verfahren, Anwendungen. Carl Hanser Verlag.

3. Liravi, F., Wang, W., & Li, D. (2019). Powder-based additive manufacturing for polymer materials: A review. Additive Manufacturing, 27, 389–417. DOI: 10.1016/j.addma.2019.03.022

4. Rösel, A., et al. (2021). Digitale Prozessketten in der Kunststofftechnik – Potenziale der Industrie 4.0. Kunststoffe, 111(3), 34–38.

5. Torres, J., Coleman, S., & Wicker, R. (2016). Effect of recycling on the mechanical behavior of 3D-printed materials. Rapid Prototyping Journal, 22(5), 869–878. DOI: 10.1108/RPJ-03-2015-0036