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 types: thermosets and thermoplastics. When heated, thermosets’ chemical bond will change, so upon cooling (the ‘cured’ state), they can no longer be melted or reshaped. Thermoplastics will soften when heated and can be totally melted into a liquid. Because no chemical change to the bond takes place, they can be reshaped without any change to the plastic properties.
Materials used in vacuum forming and injection-moulding processes are generally Thermoplastics. That way they can be heated, shaped and moulded without losing any of their inherent properties and each has their own particular merit of course.
So what are the best plastics for vacuume forming? Here are the most popular plastics used at the Vacform Group.
High Impact Polystyrene (HIPS)
This cost-effective plastic is one of the most common used in vacuum forming. It has a relatively high melting point and its formula includes a small amount of rubber, which results in a pliable material that’s easy to work with. Once cured, the finished items are durable and long lasting. HIPS is available in a number of different colours and finishes (matt and gloss) and as it’s FDA compliant, is found in a number of food and medical applications.
High Density Polythene (HDPE)
With more strength than standard polythene materials, HDPE is also resistant to oils, alcohol and acids. It’s a great choice for tougher vacuum forming or injection moulding jobs. This durable plastic can take extreme temperature ranges too. It’s usable for food projects, but is a popular choice for objects used in manufacturing and engineering.
Acrylonitrile Styrene Butadiene (ABS)
ABS plastics are highly robust and rigid and can withstand hard impacts, UV and chemical exposure. They are still flexible and easy to work with though and come in a wide range of colours and finishes. With their reasonably low cost, they are an excellent choice for many heavy-duty applications such as those found in building, automotive and engineering industries.
Polyvinyl Chloride (PVC)
PVC is another versatile plastic that suits the thermoforming process extremely well. Its base material can have additives made to make it fit different applications, from thin sheets and canvas materials to rigid pipes. Depending on the types of additives, it can be an extremely cost-effect material that can cover a number of different applications.
Acrylic is a clear and flexible material that can be thermoformed relatively easily to form many different plastic parts. It softens at high temperatures, but it doesn’t reach a liquid state until around 320 degrees, making it a great option for heat shaping. It’s available in many different colours, clarities and finishes.
This type of plastic is an economical alternative to polycarbonate and both lighter and cheaper than glass. It has generally good strength giving it shatter-resistant properties, as well as strong UV tolerance and polishability and so will often be found in point of sale and retail environments, LCD screens, greenhouses etc. Popular brand names of acrylics include Perspex and Plexiglas.
Polycarbonates, like Acrylics, are transparent and also incredibly tough and able to maintain rigidity up to140°C. It’s this hardness that sees it being used in a huge variety of demanding applications, including riot shields crash helmet and glazing. In its standard form it’s rated as slow burning, but there are grades there are also a number of grades available that pass some of the strictest fire tests known.
Polyethylene Terephtalate Glycol-Modified (PETG)
PETG is another transparent material and also extremely lightweight. It can withstand a high level of impact too. Available in many different thicknesses, it has excellent thermo-forming capability and also acts as a good stopper of solvents, gas and alcohol. PETG is used significantly in the retail environment for packaging, trays and displays.
Polyvinylidene Difluoride/Polyvinylidene fluoride (PVDF)
If purity of materials is your key objective for your project, then PVDF is an excellent choice. It’s also an excellent barrier against solvents, acids and heat and because of these properties, finds its way into a number of finished goods, such as chemical liners and pump and valve parts, where it needs to stand up to harsh chemical or heated conditions. PVDF is also able to withstand long-term exposure to ultraviolet radiation.
Here at the Vacform Group, we can discuss the different types of materials available and make a recommendation that fits your budget and gives the right performance levels for which the part will be employed for.
If you would like to discuss material types for a plastic vacuum forming job, please don’t hesitate to get in touch.