What Types of Plastics Are Used in Vacuum Forming?
There are many types of plastics that are suitable for vacuum forming parts. Each has its own specific properties and these elements will determine which is most suitable for a particular job.
Plastics fall into two distinct categories: thermosets and thermoplastics. When heated, thermosets undergo a chemical change, meaning that once they cool (or ‘cure’), they can no longer be melted or reshaped. Thermoplastics, on the other hand, soften when heated and can be fully melted into a liquid. As no chemical change occurs, they can be reshaped without altering the plastic’s properties.
Materials used in vacuum forming and injection moulding are generally thermoplastics. This allows them to be heated, shaped, and moulded without losing any inherent qualities, each offering its own particular advantages.
So, what are the best plastics for vacuum forming? Here are the most commonly used plastics at the Vacform Group.
High Impact Polystyrene (HIPS)
This cost-effective plastic is one of the most widely used in vacuum forming. It has a relatively high melting point and contains a small amount of rubber, making it a pliable material that is easy to work with. Once cured, the finished items are durable and long-lasting. HIPS is available in various colours and finishes (matt and gloss) and, as it’s FDA-compliant, is often used in food and medical applications.
High-Density Polyethylene (HDPE)
Stronger than standard polyethylene, HDPE is resistant to oils, alcohol, and acids, making it ideal for tougher vacuum forming or injection moulding tasks. This durable plastic can withstand extreme temperatures and is also suitable for food projects. However, it is most commonly used for items in manufacturing and engineering.
Acrylonitrile Styrene Butadiene (ABS)
ABS plastics are highly robust and rigid, capable of withstanding impacts, UV exposure, and chemicals. Despite this, they remain flexible and easy to work with and are available in a wide range of colours and finishes. Due to their reasonable cost, ABS plastics are excellent for heavy-duty applications, including in the building, automotive, and engineering industries.
Polyvinyl Chloride (PVC)
PVC is another versatile plastic well-suited to the thermoforming process. Additives can be introduced to its base material to make it suitable for various applications, from thin sheets and canvas materials to rigid pipes. Depending on the additives, it can be an extremely cost-effective material suitable for a wide range of uses.
Acrylic (PMMA)
Acrylic is a clear and flexible material that can be thermoformed relatively easily into a variety of plastic parts. It softens at high temperatures but only reaches a liquid state at around 320°C, making it an ideal choice for heat shaping. Available in various colours, transparencies, and finishes, acrylic is an economical alternative to polycarbonate and is both lighter and cheaper than glass. With its good strength, shatter-resistant properties, UV tolerance, and polishability, acrylic is often used in point-of-sale displays, LCD screens, greenhouses, and more. Popular brand names include Perspex and Plexiglas.
Polycarbonate
Like acrylic, polycarbonate is transparent and extremely tough, maintaining its rigidity up to 140°C. Its strength makes it ideal for a wide range of demanding applications, such as riot shields, crash helmets, and glazing. In its standard form, polycarbonate is rated as slow-burning, but there are grades available that pass the strictest fire safety tests.
Polyethylene Terephthalate Glycol-Modified (PETG)
PETG is another transparent and lightweight material that also offers excellent impact resistance. Available in various thicknesses, it has superb thermoforming capabilities and is an effective barrier against solvents, gases, and alcohol. PETG is commonly used in retail for packaging, trays, and displays.
Polyvinylidene Difluoride/Polyvinylidene Fluoride (PVDF)
If purity is a key requirement for your project, PVDF is an excellent choice. It provides an excellent barrier against solvents, acids, and heat. Due to these properties, PVDF is often used in products such as chemical liners and pump and valve parts, where it must withstand harsh chemical or high-temperature conditions. PVDF is also highly resistant to long-term UV radiation exposure.
At the Vacform Group, we can guide you through the different material options and recommend the most suitable choice for your budget and the specific performance needs of your project.
If you would like to discuss material types for a plastic vacuum forming job, please don’t hesitate to get in touch.
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