Flexible Film vs. Rigid Film Thermoforming: Application-Based Differences and Engineering Considerations

Introduction

Thermoforming packaging technology has become one of the most efficient packaging options across food, medical, and industrial sectors. As global packaging demand increases for vacuum packaging, modified atmosphere packaging (MAP), vacuum skin packaging (VSP), and high-integrity sealing solutions, manufacturers increasingly rely on thermoforming solution to form packages directly from rollstock film with high consistency, hygiene, and automation.

In most cases, the terms thermoforming, flexible film, and rigid film packaging are often used interchangeably, which leads to confusion. In reality, thermoforming is the core packaging technology, while flexible film and rigid film are two material used during the thermoforming process.

Both flexible and rigid packages are produced by heating rollstock film, forming it into a cavity, filling the product, sealing, and cutting—using the same thermoforming packaging platform. The difference lies not in the technology itself, but in its nature, such as, stiffness and thickness of the film, which determine whether the final package behaves as a flexible pack or as a self-supporting tray.

Understanding the relationship between flexible and rigid film thermoforming is therefore not about choosing a “better” technology. It is about recognizing how thermoforming technology can be engineered to meet different product requirements, distribution conditions, and presentation goals by applying different film material.

Thermoforming as a Unified Technology Platform

From an engineering perspective, both flexible and rigid film thermoforming follow the same fundamental process sequence: film heating, forming, product loading, sealing, and cutting. These steps are executed through a synchronized system controlled by the programmable logic controller (PLC).

The core distinction lies in film stiffness, forming depth, and post-forming structural behavior. Flexible films create packages that rely primarily on the product for support, while rigid films form self-supporting trays capable of maintaining their shape independently.

Research on thermoformable multi-layer materials confirms that forming stability, mechanical performance, and barrier properties are largely determined by material structure and process control rather than by machine itself (Benito-González, Martín, & Villalobos, 2020). This explains why a single thermoforming machine—when properly engineered—can support both flexible and rigid packaging strategies through adjustments in tooling, heating zones, and sealing parameters.

Flexible Film Thermoforming: Efficiency-Oriented Production

Flexible film thermoforming is widely applied in high-throughput production environments where efficiency, versatility, and cost control are primary objectives. Thin rollstock films are heated and drawn into shallow or medium-depth cavities, then sealed into compact, lightweight packages that closely conform to the product.

This format is commonly used for fresh meat, cheese blocks, sausages, seafood, and various ready-meal components. In these applications, packaging primarily serves to preserve freshness, maintain hygiene, and protect products throughout cold-chain logistics, rather than provide structural rigidity.

From an engineering standpoint, flexible film thermoforming systems are designed to support high product variability and continuous production environments. The process allows manufacturers to package products of different sizes and geometries on the same line while maintaining stable forming and sealing performance.

Flexible thermoforming is typically configured for vacuum and modified atmosphere packaging (MAP), enabling processors to optimize shelf life, hygiene, and packaging efficiency without altering the fundamental machine structure. This adaptability makes flexible film thermoforming particularly suitable for centralized processing facilities handling multiple SKUs and frequent product changeovers.

Key characteristics include:

• High-speed continuous production for large-scale processing

• Reduced material consumption and optimized cost per package

• Strong compatibility with vacuum and MAP preservation methods

Food engineering studies emphasize that when lightweight packaging materials are used—particularly for liquid or semi-liquid products—accurate filling and reliable sealing are critical to maintaining package integrity (Singh & Heldman, 2014). As a result, flexible film thermoforming is particularly effective in centralized processing facilities supplying foodservice, wholesale, and multi-SKU production lines.

Rigid Film Thermoforming: Structural Stability and Retail Performance

Rigid film thermoforming addresses a different set of packaging priorities, focusing on structural integrity, product presentation, and retail suitability. Thicker rollstock films are formed into self-supporting trays that maintain their geometry during filling, sealing, transportation, and shelf display.

This format is widely used for premium meat products, poultry, seafood, dairy slices, ready meals, and specialty foods. Rigid thermoforming enables manufacturers to package larger and more three-dimensional products while maintaining tray strength, shape stability, and consistent appearance throughout filling, distribution, and retail display.

Rigid thermoforming technology is most commonly paired with MAP and VSP technologies, where gas composition, sealing integrity, and tray rigidity work together to extend shelf life and enhance visual appeal. Compared with flexible formats, rigid trays offer superior resistance to deformation, stacking pressure, and handling stress across extended distribution chains.

Packaging research has shown that package structure and sealing performance play a direct role in maintaining product quality and microbial stability under modified atmosphere conditions (Caleb et al., 2013). In addition to protection, rigid film thermoforming also supports high-quality visual presentation, enabling clear product visibility and, where required, compatibility with skin-style packaging concepts that enhance product appearance by tightly conforming to the product surface.

For this reason, rigid film thermoforming is often selected for retail-ready packaging where both product protection and shelf presentation are critical.

Application-Based Comparison: Flexible vs. Rigid Formats

When evaluated through application requirements rather than material labels, the distinction between flexible and rigid thermoforming becomes clear:

Flexible film thermoforming prioritizes throughput, material efficiency, and operational flexibility, making it well suited for high-volume processing and multi-product production lines. In contrast, rigid film thermoforming focuses on tray stability, shelf presentation, and extended shelf life, supporting premium product positioning and retail-oriented distribution channels.

In real-world production environments, many processors operate both formats simultaneously. Flexible thermoforming lines may supply bulk or foodservice channels, while rigid thermoforming lines produce retail-facing products. This parallel deployment highlights the importance of application-driven equipment selection rather than format-based assumptions.

Engineering Considerations in Format Selection

Selecting between flexible and rigid thermoforming formats requires evaluating how the packaging solution performs across three core dimensions:

• Product characteristics – including moisture content, fat levels, product geometry, and sensitivity to deformation, which directly influence forming behavior and sealing requirements.

• Presentation requirements – such as whether the product is intended for bulk distribution or retail display, the need for tray support, product visibility, and overall shelf appearance.

• Protection performance – including resistance to physical impact during handling and transportation, sealing integrity, and the ability to extend shelf life through vacuum, MAP, or VSP.

Studies on hygienic packaging equipment design emphasize that closed-system processing, reduced manual handling, and integrated automation significantly improve food safety and operational stability (Moerman & Tollenaere, 2017). These principles apply equally to both flexible and rigid thermoforming systems, particularly in high-capacity industrial operations.

Sustainability and Material Recyclability in Thermoforming Packaging

Sustainability in thermoforming packaging is increasingly driven by material structure optimization and end-of-life design, rather than by disruptive changes to established packaging formats. Current developments focus on improving how packaging structures can be separated, identified, and recovered after use, allowing them to integrate more effectively into existing recycling systems.

One important direction is the adoption of separable packaging structures, where forming and lidding components are intentionally designed to be detached from each other. This improves post-use handling and enhances sorting efficiency within recycling streams. In parallel, material systems are evolving toward mono-material or material-compatible multilayer designs, reducing structural complexity while maintaining required barrier and sealing performance.

Material efficiency also plays a critical role in sustainable packaging development. Thermoforming enables precise control over forming thickness and cavity geometry, allowing manufacturers to reduce material usage per package without compromising functional integrity. This source-reduction approach contributes directly to lower overall material consumption across high-volume production.

By combining recyclable-oriented material design with stable, repeatable thermoforming processes, manufacturers can move progressively toward more sustainable packaging solutions—supporting environmental objectives while maintaining product protection, hygiene standards, and industrial-scale reliability.

Conclusion

Flexible and rigid film thermoforming should be understood as two material-based packaging strategies, rather than as different packaging technologies. Each approach addresses distinct application needs, ranging from high-throughput efficiency to structural stability and retail presentation.

Manufacturers that evaluate thermoforming through real production scenarios—rather than simplified material comparisons—are better positioned to build scalable, adaptable packaging operations. As tray-based vacuum and MAP packaging continue to expand across global food markets, thermoforming platforms with strong engineering foundations and application flexibility will remain a critical driver of long-term packaging performance.

References:

1. Benito-González, I., Martín, M., & Villalobos, R. (2020). Mechanical and barrier performance of thermoformed multilayer bio-based films. Polymers, 12(6), 1327. https://doi.org/10.3390/polym12061327

2. Singh, P., & Heldman, D. R. (2014). Introduction to food engineering (5th ed.). Academic Press.

https://www.sciencedirect.com/book/9780123985309/introduction-to-food-engineering

3. Moerman, F., & Tollenaere, A. (2017). Hygienic design of food packaging equipment. Food Safety Magazine.

https://www.food-safety.com/articles/5400-hygienic-design-of-food-packaging-equipment

4. Caleb, O. J., Mahajan, P. V., Al-Said, F. A.-J., & Opara, U. L. (2013). Modified atmosphere packaging technology of fresh and fresh-cut produce and the microbial consequences—A review. Food and Bioprocess Technology, 6(2), 303–329.

https://link.springer.com/article/10.1007/s11947-012-0932-4

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