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What is Thermoforming?

Thermoforming machine

Simply speaking, thermoforming is a manufacturing process in which a plastic sheet is heated to make it pliable and flexible, and then a force is applied to the sheet to stretch it over a mold so the sheet takes on the shape of the mold. The forces applied can be vacuum, pressure, mechanical, or a combination of these methods.  

If you’ve ever made caramel apples by heating a sheet of caramel over the apple and watching it melt and take on the shape of the apple, you understand thermoforming. 

Thermoforming is used in multiple markets to make a wide variety of products, things such as bathtubs, automotive panels, internal door liners for refrigerators, bins, pallets, trays, containers, and much more. 

In this article, we provide:

  • an overview of thermoforming
  • the types of thermoforming
  • the benefits of thermoforming


At its core, thermoforming consists of two main steps: heating and forming. That’s where the process gets its name: Thermo (“heat”) + forming.

Heating is accomplished in several ways. Most often, infrared heaters are used. These can be located on one side or both sides of the plastic. The length of time the plastic must be heated can vary depending on the plastic being used, its thickness, and its color. The goal is to soften the plastic enough that it can be stretched to fit into the contours of the mold, but not heat it so much that it melts or deforms.

Forming is achieved in a variety of ways, as described below. In all cases, the goal is to get the warmed plastic to take on the shape of the mold to create the desired part. Even when plastic is heated, it does not become pliable enough to fit snugly into the mold by itself. Force must be applied to the plastic in a way that does not damage it but makes it fit into the nooks and crevices of the mold. 


In thermoforming, the forming function can be achieved in three ways:

  • With vacuum
  • With pressure
  • Mechanically


The earliest thermoforming method, developed in the 1950s, was vacuum thermoforming. In vacuum thermoforming, negative pressure is used to draw the heated plastic sheet onto the mold. 

Vacuum thermoforming is quick, efficient, and easy to implement. It is ideal for shallow parts that don’t have many deep cavities or intricacies.


In contrast to the vacuum method, pressure thermoforming uses positive pressure (i.e., air) to force the heated plastic sheet onto the mold. 

Pressure forming has several advantages:

  • Higher pressure can be applied
  • More detailed shapes and textures can be achieved
  • Deeper holes in the mold can be filled


In mechanical thermoforming, no air or pressure is used. Instead, matching positive and negative molds are used to compress the heated plastic sheet into shape. It is very much like a stamping process.

The advantage of mechanical thermoforming include: 

  • better dimensional control 
  • better surface detailing on both sides of a part. 

The disadvantage of mechanical thermoforming is that two mold halves are needed. In vacuum and pressure thermoforming, only one mold is used. 


Why do manufacturers choose thermoforming as opposed to other plastic part-making processes such as injection molding? Well, thermoforming offers these advantages. 

  • Large Parts at Low Cost.  For large parts, thermoforming beats other plastic methods. For example, on a 45”x48” part, thermoforming tooling is roughly half the cost of an injection mold. The per-piece piece price is usually less, too.
  • Rugged, durable performance. With heavy-gauge thermoforming, we can create larger, thicker packaging for items that need more durable containers. 
  • Low Tooling Investment. With vacuum and pressure thermoforming, only one mold is needed to create a part.
  • Rapid Development.  Thermoforming utilizes prototype tools made from wood or epoxy. These tools can be used to create several finished parts that truly represent the final product, which is better for testing. Also, with thermoforming, the prototype is formed from the exact same material as the final product, allowing you to identify design or fit issues sooner, before going to production tooling.
  • Product Design Advantages. Thermoforming can capture more detail and textures in a part than other plastic methods. 


At Vantage Plastics, we design and manufacture many types of thermoformed products. Protecting products in transit and in storage is extremely vital and is what we do best. Within our facility, we have six single sheet machines, five twin sheet machines, and one sample machine dedicated to prototype samples. Anything needed for shipping or storage, we can create a package for it.

We have many solutions to meet your unique requirements. Contact us or call 989-846-1029 to discover how we can serve you!