What Are the Common Thermoforming Terms and Glossary?

October 2, 2023 8:22 pm Published by Leave your thoughts

Thermoformer,Top,Film,Reel,Holder,Film,Unwinding,System,Processing,PackagingThermoforming is a widely used manufacturing process in which plastic sheets are heated and formed into specific shapes through the use of heat, pressure, and vacuum. Whether you are involved in the thermoforming industry or simply looking to learn more about it, understanding the common thermoforming terms and glossary can be beneficial. In this blog post, we will discuss some of the most commonly used terms in thermoforming.

1. Thermoforming:

Thermoforming is the process of heating a plastic sheet to a pliable temperature and then using a mold to shape it into a desired form. This process is widely used in various industries, including packaging, automotive, and medical.

2. Plastic Sheet:

Plastic sheet refers to a flat and thin piece of plastic material that is used as the raw material in thermoforming. These sheets come in different sizes, thicknesses, and types of plastics, such as ABS, polycarbonate, and PVC.

3. Mold:

A mold is a tool or form used in thermoforming to shape the heated plastic sheet. It can be made of various materials, including aluminum, steel, or composite materials. The mold determines the final shape and details of the formed part.

4. Vacuum Forming:

Vacuum forming is a type of thermoforming in which a vacuum is used to draw the heated plastic sheet into a mold. The pressure difference generated by the vacuum helps in shaping the plastic sheet accurately.

5. Pressure Forming:

Pressure forming is another thermoforming technique that involves the use of both heat and pressure to form the plastic sheet. The plastic is pressed against the mold using compressed air, which enhances the details and improves the surface finish of the formed part.

6. Solid Sheet Thermoforming:

Solid sheet thermoforming refers to the process of using a solid plastic sheet to create a formed part. This method is advantageous when precision and durability are needed.

7. Roll-Fed Thermoforming:

Roll-fed thermoforming is a process in which a continuous roll of plastic sheet moves through the thermoforming machine. The sheet is heated, formed, and then cut into individual parts.

8. In-Line Thermoforming:

In-line thermoforming is a continuous production process in which a thermoforming machine is directly connected to an extruder. The plastic sheet is extruded and immediately formed into parts without the need for additional handling.

9. Twin-Sheet Thermoforming:

Twin-sheet thermoforming involves the simultaneous formation of two plastic sheets that are bonded together to create a hollow, double-walled part. This technique is commonly used in the production of containers and enclosures.

10. Plug Assist:

A plug assist is a tool used to shape the heated plastic sheet accurately and press it against the mold during the thermoforming process. It helps in achieving uniform thickness and reducing material waste.

11. Draw Ratio:

The draw ratio is a term used to describe the amount of elongation or stretching of the plastic sheet during thermoforming. It is typically calculated by dividing the final length of the formed part by the initial length of the plastic sheet.

12. Sagging:

Sagging refers to the undesired stretching or deformation of the plastic sheet during the thermoforming process. It can occur when the sheet is heated too much or when the mold design does not support the material properly.

13. Trim:

Trim refers to the excess plastic material that is removed from the formed part after thermoforming. Trimming may involve cutting, routing, or punching the excess material to achieve the desired final shape.


Thermoforming is a versatile and efficient process that offers numerous advantages in terms of design flexibility, cost-effectiveness, and production speed. By familiarizing yourself with these common thermoforming terms and glossary, you can gain a better understanding of the process and communicate effectively with plastic fabrication professionals.

Got Questions? Let Us Help!

D&D Plastics is a design and development company that assists clients in taking a concept or design and developing it into a viable product. With over 35 years of experience in vacuum forming and fabrication, we are pushing the boundaries of what we can do with plastic today. At D&D Plastics, if you can think it up, we can make it! We specialize in custom plastics, sheets of plastic, tubing, thermoforming, vacuum forming, acrylic, plastic rod, ABS and polycarbonate, and MUCH more. We love what we do and strive to become the best. We focus on creating a win-win with our customers and want them to succeed and grow with us. Our customers always have, and always will come first, and no project is too small! Contact us today and learn more about what we can do for you!

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