Table of Contents
Introduction
Selecting the right material is one of the most critical decisions in the thermoforming process. The choice of thermoplastic impacts everything from durability and flexibility to cost and manufacturability. Different materials offer unique benefits, such as impact resistance, heat stability, chemical resistance, or optical clarity.
This article explores the key considerations for choosing thermoforming materials and provides an overview of the most commonly used thermoplastics to help manufacturers optimize performance, cost, and production efficiency.
1. Key Factors in Thermoplastic Selection
Not all plastics behave the same during thermoforming. Some stretch uniformly, while others thin out unpredictably. Some offer excellent heat and chemical resistance, while others are better suited for food packaging or high-impact applications. The right material must balance performance, cost, and ease of manufacturing.
1.1 Rigidity vs. Flexibility
The mechanical strength of a material is a major consideration in thermoforming. Depending on the application, a plastic should be rigid enough to hold its shape or flexible enough to allow deformation without cracking.
- Rigid Plastics: High-Impact Polystyrene (HIPS), ABS, Polycarbonate (PC)
- Flexible Plastics: Low-Density Polyethylene (LDPE), Polypropylene (PP)
For structural components such as automotive panels or enclosures, rigid plastics are preferred. For packaging, liners, or food trays, flexible materials like polyethylene (PE) or polypropylene (PP) work best.
1.2 Transparency vs. Opacity
Many thermoformed products require optical clarity, particularly in medical trays, display covers, and protective shields. However, opaque materials are often used in industrial enclosures, automotive parts, and packaging applications.
- Transparent Materials: PETG, Polycarbonate (PC), Acrylic
- Opaque Materials: ABS, HIPS, Kydex
When choosing a transparent material, factors like scratch resistance, UV resistance, and impact strength should also be considered.
1.3 Heat and Chemical Resistance
In applications where parts will be exposed to high temperatures, aggressive chemicals, or harsh environments, material selection becomes even more critical.
- High-Heat Resistance: Polycarbonate (PC), Polypropylene (PP), Kydex
- Chemical Resistance: Polyethylene (PE), Polypropylene (PP), PVC
For instance, medical and laboratory equipment often requires polypropylene (PP) for its chemical stability, while outdoor signage benefits from UV-resistant acrylic.
1.4 Food Safety Considerations
When manufacturing food containers, trays, or packaging, FDA-compliant materials must be used. These materials should be non-toxic, resistant to contamination, and capable of withstanding heat and moisture exposure.
- Common Food-Safe Materials: PETG, Polypropylene (PP), High-Impact Polystyrene (HIPS)
PETG is widely used for clamshell packaging and medical trays, while polypropylene is preferred for microwave-safe food containers.
2. Overview of Common Thermoforming Materials
2.1 High-Impact Polystyrene (HIPS)
✅ Low cost, easy to form, lightweight
⚠️ Brittle in cold temperatures, poor UV and heat resistance
🔹 Applications: Packaging trays, covers, lightweight enclosures
HIPS is one of the most commonly used thermoforming materials due to its affordability and ease of processing. However, it is best suited for indoor applications since it lacks UV and weather resistance.
2.2 PETG (Polyethylene Terephthalate Glycol-Modified)
✅ Excellent clarity, strong impact resistance, food-safe
⚠️ Soft surface, prone to scratching
🔹 Applications: Medical trays, food packaging, display cases
PETG is a top choice for clear thermoformed parts, especially in medical and food applications, due to its non-toxic properties and high impact strength.
2.3 ABS (Acrylonitrile Butadiene Styrene)
✅ High impact resistance, tough, chemically resistant
⚠️ Can be flammable unless modified with additives
🔹 Applications: Automotive panels, protective covers, enclosures
ABS is widely used in automotive and industrial applications due to its durability and ability to withstand mechanical stress.
2.4 Kydex (ABS/PVC or Acrylic/PVC Blends)
✅ High impact strength, flame retardant, chemical resistant
⚠️ Higher cost than standard ABS
🔹 Applications: Aircraft interiors, medical enclosures, protective cases
Kydex is ideal for applications requiring flame retardancy and impact resistance, making it a preferred material for aerospace and high-performance industrial applications.
2.5 Polycarbonate (PC)
✅ High stiffness, impact strength, heat resistance
⚠️ Expensive, difficult to form into fine details
🔹 Applications: Protective shields, medical equipment, lighting covers
Polycarbonate is one of the toughest thermoforming plastics, often used in applications where high impact strength and transparency are required.
2.6 Polyethylene (PE) – HDPE & LDPE
✅ Chemically resistant, flexible (LDPE) or rigid (HDPE), low cost
⚠️ High shrinkage rate, which reduces tooling lifespan
🔹 Applications: Containers, liners, chemical-resistant trays
Polyethylene is highly versatile and widely used for chemical storage and industrial applications, where resistance to harsh environments is critical.
2.7 Polypropylene (PP)
✅ Excellent chemical resistance, moderate rigidity, food-safe
⚠️ Higher shrinkage rate, lower impact resistance than PE
🔹 Applications: Food containers, lab equipment, automotive components
Polypropylene is one of the most widely used thermoplastics due to its chemical resistance and high-temperature stability. It is commonly found in microwave-safe food packaging and laboratory applications.
2.8 PVC (Polyvinyl Chloride)
✅ Good mechanical strength, electrical insulation, and chemical resistance
⚠️ Requires additives for impact resistance
🔹 Applications: Enclosures, piping, signage
PVC is used in chemical and electrical applications, where durability and corrosion resistance are required.
2.9 Acrylic
✅ UV-resistant, rigid, excellent optical clarity
⚠️ Brittle, difficult to form into sharp bends
🔹 Applications: Display cases, outdoor signage, skylights
Acrylic is the preferred choice for outdoor and high-clarity applications, such as display windows and light covers.
3. Optimizing Material Usage for Cost and Efficiency
3.1 Custom Sheet Sizes for Reduced Waste
Standard plastic sheets come in 48″ x 96″ sizes, but ordering custom sheet sizes for large-scale production can minimize material waste and improve yield.
- Standard Order Minimums: 500–5000 lbs, depending on the supplier.
- Custom Cutting Options: Available for optimizing part layout and reducing scrap.
3.2 Scrap Factor and Recycling Considerations
Thermoforming typically generates 10–20% material waste due to trimming and cutouts. Using recycled materials or regrinding excess plastic can help reduce costs and improve sustainability.
4. Get the Right Thermoforming Material with RapidMade
At RapidMade, we help manufacturers choose the best thermoplastic materials for their applications. Whether you need impact-resistant ABS, optically clear PETG, or heat-stable polypropylene, our team of experts can guide you through material selection, tooling, and production optimization.
📞 Contact us today to discuss your thermoforming needs!
📩 Email: [email protected]
🌐 Website: rapidmade.com
With the right materials and expert guidance, you can enhance durability, reduce costs, and streamline your production process. Let RapidMade be your partner in efficient, high-performance thermoforming!
