Types of Plastics Used in Vacuum Forming

Vacuum forming is a widely used manufacturing process that transforms plastic sheets into various shapes and products by heating the plastic until it becomes pliable, then using a vacuum to pull it over a mold. This method is particularly cost-effective for low to medium production runs and is commonly used in industries like packaging, automotive, and consumer goods. The success of vacuum forming¹ largely depends on selecting the right type of plastic, as different materials offer unique properties suited to specific applications.

Vacuum forming heats a plastic sheet, stretches it over a mold, and uses a vacuum to shape it, ideal for simple to moderately complex parts like packaging or automotive components.

This article explores the types of plastics that can be used in vacuum forming, providing insights into their properties, applications, and how to choose the best material for your project. Whether you're new to vacuum forming or looking to optimize your material selection, this guide will help you make informed decisions.

What Are the Common Plastics Used in Vacuum Forming?

Vacuum forming relies on thermoplastics², which can be heated and reshaped multiple times. Each plastic has distinct properties that make it suitable for specific applications.

Common plastics for vacuum forming include ABS, acrylic (PMMA), PETG, HIPS, PVC, polycarbonate (PC), and HDPE, each chosen for properties like durability, clarity, or cost-effectiveness.

Acrylonitrile Butadiene Styrene (ABS)

ABS is a popular choice for vacuum forming due to its toughness and impact resistance. It’s widely used in automotive parts, machine housings, and consumer goods like toys. ABS can be easily painted or printed on, making it versatile for various finishes.

Acrylic (PMMA)

Acrylic, or polymethyl methacrylate (PMMA), is known for its clarity and brittleness. It’s ideal for applications where transparency is important, such as signs, displays, and light diffusers. However, it’s less stretchy and requires careful temperature control during forming.

Polyethylene Terephthalate Glycol (PETG)

PETG is a food-safe plastic³ with high impact strength and clarity. It’s commonly used in medical trays, food containers, and point-of-sale displays. PETG is highly formable and suitable for applications requiring sterilization.

High-Impact Polystyrene (HIPS)

HIPS is an affordable and versatile plastic, making it a go-to for toys, packaging, and displays. It’s easy to form and can be finished with various textures, paints, or prints.

Polyvinyl Chloride (PVC)

PVC is chemical-resistant and flame-retardant, making it suitable for packaging, car trims, and machine guards. It’s easy to form in thin gauges but may require specialist inks for printing.

Polycarbonate (PC)

Polycarbonate is extremely strong, clear, and heat-resistant, making it ideal for safety shields, skylights, and aircraft trim. It requires higher forming temperatures but offers excellent detail retention.

High-Density Polyethylene (HDPE)

HDPE is durable and chemical-resistant, often used for containers, outdoor parts, and vehicle components. It has high shrinkage, so careful tolerance control is needed during forming.

Why Choose Vacuum Forming Over Other Methods?

Vacuum forming offers several advantages, especially for specific production needs and design requirements.

Vacuum forming is cost-effective for low to medium production runs⁴, allows quick design changes, and is ideal for large, simple to moderately complex parts.

Additional Benefits:

• Consistency: The same mold ensures repeatable results.

• Single-Piece Construction: Produces seamless parts, enhancing durability.

• Material Efficiency: Uses less material than other methods for similar parts.

However, vacuum forming may require post-processing like trimming or painting, which can add to the overall cost and time.

How to Choose the Right Plastic for Your Project?

Selecting the appropriate plastic depends on several factors, including cost, durability, environmental resistance⁵, and regulatory requirements.

Choose plastics based on project needs: cost⁶ (HIPS, PVC), durability⁷ (ABS, PC), clarity⁸ (acrylic, PETG), or environmental resistance (HDPE, PC).

Cost Considerations

For budget-conscious projects, HIPS and PVC are low-cost options⁹. They are suitable for applications where high strength or special properties are not required, such as disposable packaging or simple displays.

Durability and Strength

If your project requires tough, impact-resistant parts¹⁰, ABS or polycarbonate are better choices. These materials are ideal for automotive components, machine housings, or safety equipment.

Clarity and Aesthetics

For applications where transparency is important, such as signs or displays, acrylic or PETG are excellent options. Polycarbonate also offers clarity but is stronger and more heat-resistant.

Environmental Resistance

For outdoor use or exposure to chemicals, HDPE or polycarbonate are more suitable due to their durability and resistance to UV light and chemicals.

Regulatory Compliance

If your project involves food contact or medical applications, PETG is a safe choice as it is FDA-approved¹¹ and sterilizable.

Conclusion

Vacuum forming is a versatile and cost-effective manufacturing process suitable for a wide range of applications, from packaging to automotive parts. By understanding the properties of different plastics—such as ABS, acrylic, PETG, HIPS, PVC, polycarbonate, and HDPE—you can select the right material for your project based on factors like cost, durability, clarity, and environmental resistance.