Fiberglass vs Thermoforming Plastics: Which Process is Right for Your Project?

Fiberglass vs. Thermoforming Plastics: How to Choose?

Hengtuopu’ core competence lies in the design, manufacturing, and production of custom thick-spec thermoformed plastic parts.

Both thermoforming and fiberglass molding processes can be used to create similar parts. However, when selecting the right process for a specific plastic part, it’s important to consider the pros and cons of each. The information on this page provides general guidance on how to choose between fiberglass and thermoforming.

Thermoforming Plastic Process

Thermoforming is a plastic manufacturing process that involves heating a rigid thermoplastic sheet and using vacuum and/or pressure to shape the sheet into a three-dimensional form. Thermoforming is typically used for production volumes ranging from 250 to 3000 parts per year, offering lower mold costs, faster product development cycles, and parts with color and texture options.

Fiberglass Molding (FRP/GRP) Process

Fiberglass molding is a process where resin reinforced with glass fibers is molded into useful shapes. The resin is applied in multiple layers to increase strength and achieve the desired thickness. This process and material are best suited for making large, high-strength structures, but it comes with higher mold costs and slower production times.

Choosing the Best Manufacturing Process for Your Plastic Parts

Hengtuopu works with clients to ensure that the technology, production process, and materials are best suited for each job. Here are some guidelines and considerations for choosing between thermoforming and fiberglass molding (FRP/GRP):

Volume

Fiberglass (FRP/GRP) parts are primarily used for small-batch production and prototype projects. Thermoforming, on the other hand, is more cost-effective for production volumes of 250 to 3000 parts per year. For high volumes, neither thermoforming nor fiberglass molding is particularly cost-effective.

Thermoplastic Materials and Industry Compliance

Thermoplastic Olefins (TPO) are commonly the preferred alternative to fiberglass for parts. Compared to fiberglass, TPO materials are more durable, crack-resistant, UV-resistant, have better conductivity, and are lighter.

Various thermoplastic manufacturers, such as Kydex or Spartech, offer specialty thermoplastic materials designed for specific industries and environments, with different performance characteristics like tensile strength, flammability, chemical resistance, UL certification, and weight. Many of these products meet industry standards and fire, smoke, and toxicity (FST) requirements for aerospace, public transportation, and medical devices, such as EN 45545, DIN 5510-2, NF P 92-501 (-504, – 505), NF F 16-101/102, FRA Type I, FRA Type II, ASTM E162, ASTM E662, SMP-800C, or BSS 7239.

For more information on how to match the ideal thermoplastic that meets industry requirements with your project needs, please contact us.

Lead Time

The fiberglass molding process is labor-intensive and typically requires multiple tools to produce one part, which leads to slower production speeds, higher costs, and longer lead times compared to thermoformed plastic production.

In contrast, thermoforming is highly automated and relatively simple, requiring fewer labor resources. Most applications use just one tool for each part. As a result, thermoforming typically offers shorter lead times and lower tool and labor costs compared to fiberglass molding. From a pure process perspective, for smaller production volumes of 250–3000 parts per year, thermoforming is generally faster and more cost-effective than fiberglass molding.

Design, Finish, and Branding

The fiberglass process can produce high-quality finishes, but its applications are limited. Thermoformed plastics offer a variety of colors and surface textures. Techniques like screen printing, thermoforming printing, and post-processing painting can also be used to enhance branding and graphics potential on thermoformed plastic parts. The ability to achieve precise tolerances and complex geometric designs is only feasible for a limited number of applications made with fiberglass, making these applications costly or difficult to achieve otherwise. These advantages allow designers greater freedom to create more aesthetically pleasing and functional complex modern designs.

Tools

Due to the complexity and labor-intensive nature of fiberglass production, open-contact molding processes typically require multiple tools to complete a part. This increases tool costs and production time requirements for each part.

Thermoforming, however, is highly automated, requiring less labor, and most applications need only one tool per part. As a result, tooling costs are lower, and productivity is greatly enhanced compared to fiberglass molding.

Weight Considerations

Thermoformed plastic parts are lighter than fiberglass parts, typically reducing part weight by 30%. This fact is further supported by comparing the specific gravities of raw material products from industry suppliers like Covestro (formerly Bayer MaterialScience) or SEKISUI SPI (formerly KYDEX, LLC).

Thermoforming Plastic vs. FRP Weight Comparison Thermoformed plastics and their manufacturing process are environmentally safe, as the materials are recyclable, and most thermoplastic raw materials are free from volatile organic compounds (VOCs). In contrast, the fiberglass process generates significant amounts of harmful styrene and is not recyclable.

Summary Comparison Table

Factor Thermoforming Fiberglass Molding (FRP/GRP)
Production Volume 250–3000 parts/year (cost-effective for this range) Small batch, prototypes (less cost-effective at higher volumes)
Material Type Thermoplastic (e.g., TPO) Glass-reinforced resin
Mold Cost Lower Higher
Lead Time Shorter (typically under 10 weeks) Longer
Design Flexibility High (complex shapes, custom finishes) Limited (higher cost for complex designs)
Weight 30% lighter than fiberglass Heavier
Environmental Impact Recyclable, VOC-free Non-recyclable, generates harmful styrene
Strength Suitable for general uses, lighter parts Higher strength for large structures
Compliance Industry-specific thermoplastic options available Suitable for high-strength, large structures

This comparison table can help you make an informed decision based on your production needs, design goals, and material requirements. For additional guidance or a consultation, feel free to reach out to Hengtuopu.