What Types of Products or Shapes are Suitable for the Thermoforming Process?

Thermoforming is a versatile manufacturing technique that heats thermoplastic sheets and molds them into a variety of products by applying vacuum or pressure, followed by cooling to set the shape. This process is celebrated for its cost-effectiveness and efficiency, making it a staple in industries such as packaging, automotive, and appliances. However, its suitability depends heavily on the types of products and shapes it can effectively produce.

Thermoforming is ideal for products like packaging trays¹, automotive panels², and appliance liners, with shapes that are relatively shallow, have gentle curves, and avoid sharp corners or undercuts.

In this blog post, we’ll dive into the common products and shapes that thrive with thermoforming³, explore key design considerations, and compare it to other manufacturing methods. Whether you’re designing a new product or optimizing production, this guide will illuminate when thermoforming shines.

What are the Common Products Made Using Thermoforming?

Thermoforming excels at producing lightweight, durable items with large surface areas, serving a broad range of industries. Its adaptability to both thin- and heavy-gauge materials makes it a go-to for applications where cost and speed outweigh the need for ultra-precise tolerances.

Common thermoformed products include packaging trays, automotive interior panels⁴, refrigerator liners, and medical device casings, all benefiting from the process’s ability to handle large, shallow designs efficiently.

Product Type	Industry	Notes
Packaging Trays	Food, Electronics	Thin-gauge, disposable
Automotive Panels	Transportation	Heavy-gauge, durable
Appliance Liners	Home Appliances	Heat-resistant, large
Medical Casings	Healthcare	Sterile, precise

Packaging Trays

Thermoforming dominates the production of packaging trays, blister packs, and clamshells, typically using thin-gauge sheets (under 0.060 inches). These items are perfect for high-volume, single-use applications in food and electronics, offering quick production and minimal material use. Companies like Amcor leverage thermoforming for custom, protective packaging solutions.

Automotive Interior Panels

In the automotive sector, thermoforming crafts interior components like door panels and dashboard covers from heavy-gauge sheets⁵ (over 0.060 inches). These parts demand durability and aesthetics, often enhanced by pressure forming⁶ for detailed textures. Faurecia uses this process to create lightweight, robust panels meeting rigorous standards.

Appliance Liners

Thermoforming produces seamless liners for refrigerators and ovens, utilizing materials like ABS for heat resistance and insulation. Its ability to form large, single-piece components cost-effectively is a key advantage. Whirlpool relies on this method for efficient appliance manufacturing.

Medical Device Casings

For healthcare, thermoforming creates precise, sterile casings and trays using materials like PETG. Its compatibility with sterilization processes makes it invaluable. Tek Pak specializes in such solutions, ensuring functionality and safety.

What Shapes are Suitable for Thermoforming?

The shapes best suited for thermoforming align with the process’s reliance on stretching a flat sheet over or into a mold. Geometric constraints like depth, angles, and curvature play a critical role in determining feasibility.

Suitable shapes for thermoforming are relatively shallow with gentle curves, a draw ratio up to 3:1⁷, and draft angles of 1.5–5 degrees⁸ to ensure easy mold release.

Draw Ratio

The draw ratio—mold surface area divided by the original sheet area—should ideally not exceed 3:1. This means a part’s depth shouldn’t be more than three times its width to avoid excessive thinning. For example, a 6-inch deep tray should be at least 2 inches wide.

Draft Angles

Draft angles (1.5–5 degrees) taper side walls to ease part removal from the mold. Deeper features need larger angles—e.g., a 4-inch deep part might require 3 degrees, while a shallow one could use 1.5 degrees.

Avoiding Sharp Corners and Undercuts

Sharp corners thin the material unevenly, and undercuts complicate mold release. Generous radii and simplified designs are preferred, though movable mold parts can handle undercuts at added cost. A tray with rounded edges forms better than one with sharp corners.

Complex Shapes with Pressure Forming

While vacuum forming suits simple shapes, pressure forming uses higher pressure⁹ for detailed, textured parts—like automotive panels with intricate designs. Ray Products showcases this capability effectively.

What are the Design Considerations for Thermoforming?

Successful thermoforming hinges on thoughtful design to balance manufacturability and performance. Key parameters guide this process.

Key design considerations for thermoforming include maintaining a draw ratio of up to 3:1, incorporating draft angles of 1.5–5 degrees, and avoiding sharp corners and undercuts¹⁰.

Design Parameter	Recommended Value	Notes
Draw Ratio	Up to 3:1	Avoid excessive thinning
Draft Angles	1.5–5 degrees	Larger for deeper features
Corner Radius	≥ Material thickness	Ensures even distribution
Undercuts	Avoid or use movable cores	Increases cost and complexity

Material Selection

Materials like PET (for packaging clarity), ABS (for impact resistance), and PP (for heat resistance) dictate formability and properties. Choosing the right one aligns with the product’s needs.

Wall Thickness

Thinning occurs in stretched areas, so starting with a thicker sheet (e.g., 0.125 inches for a 0.060-inch final thickness) or adding ribs ensures strength without excess material.

Tolerances

With tolerances around ±0.020 inches, thermoforming suits less precise applications. Tighter specs may require secondary machining, as seen in some medical casings.

How Does Thermoforming Compare to Other Manufacturing Processes?

Thermoforming’s strengths and limitations become clear when compared to alternatives like injection molding and blow molding.

Thermoforming offers lower tooling costs¹¹ and faster lead times¹² than injection molding but is less precise and not suitable for highly complex or hollow parts.

Thermoforming vs. Injection Molding

• Tooling Costs: Thermoforming’s tooling is 50–90% cheaper—$10,000 vs. $100,000 for a large panel.

• Lead Times: Weeks vs. months for tool creation.

• Precision: Injection molding wins for tight tolerances and complexity.

• Material Use: Thermoforming excels for large, thin-walled parts.

Thermoforming vs. Blow Molding

• Geometry: Blow molding suits hollow items (e.g., bottles); thermoforming fits open, shallow parts.

• Efficiency: Thermoforming handles larger parts better.

• Speed: Both are fast, but thermoforming scales efficiently for flat designs.

Conclusion

Thermoforming shines for producing large, lightweight parts¹³ like packaging trays, automotive panels, and appliance liners, especially in low to medium volumes. Its cost-effectiveness and speed make it a standout, though it’s less suited for complex, precise, or hollow designs. By mastering suitable products, shapes, and design considerations, you can harness its full potential.