Vacuum forming, also known as thermoforming, is a manufacturing process in which a thermoplastic material is heated to a pliable forming temperature, formed to a specific shape in a mold, and trimmed to create a usable part or component. Vacuum forming is an economical, quick and reliable process for creating large scale, intricate parts and components in prototype, low volume and high volume production rates.
History
Vacuum forming was developed in the late 19th century as a way to quickly and economically mass produce items by using heat and vacuum to create intricate parts and components. The process has evolved over the years and today is often used in place of more traditional fabrication processes such as machining and injection molding.
Overview of Process
The vacuum forming process begins with a thermoplastic sheet, known as a preg (or pre-formed blanks in some circles), that has been heated to a temperature where it is soft, pliable and able to be formed. The preg is then draped over a mold or pattern and a vacuum is applied to the material which removes all of the air from between the preg and the mold or pattern, causing the preg to be sucked into the mold and conforming perfectly to its contours.
Once the preg is fully cooled, excess preg material is trimmed away using a hot knife, leaving a part that perfectly replicates the mold or pattern. The part is then removed form the mold or pattern and is ready to be used.
Materials
Vacuum forming can be used with a variety of materials, including Acrylic, ABS, Polyethylene, UHMW and Polycarbonate. Each material has its own advantages, such as:
Acrylic – Acrylic is an excellent option for vacuum forming due to its superior clarity, rigidity, and ease of forming.
ABS – ABS is widely used for forming due to its strength, durability, and ability to be easily painted and modified.
Polyethylene – Polyethylene is a lightweight, durable material that is widely used in vacuum forming applications.
UHMW – UHMW is a highly durable material that offers superior abrasion resistance, making it a great option for parts that will be subjected to heavy wear and tear.
Polycarbonate – Polycarbonate is often used due to its superior impact resistance and clarity.
Advantages
Vacuum forming offers a number of advantages over traditional fabrication processes. Some of the most important benefits include:
Strength – Vacuum formed parts are strong and durable, making them well suited for applications where strength and durability are important.
Light Weight – Vacuum forming can create parts that are light weight and easy to handle.
Efficiency – Vacuum forming can be used to quickly and efficiently create parts in a variety of sizes and shapes.
Cost – Vacuum forming is generally less expensive than other fabrication processes, making it a cost effective solution for many applications.
Environmentally Friendly – Vacuum forming requires very little energy, making it an environmentally friendly process.
Disadvantages
Although vacuum forming is a highly efficient process, there are some drawbacks, such as:
Limited Size – Parts created using vacuum forming are limited in size and complexity, making them unsuitable for some applications.
Cost – Vacuum forming may not be the most cost effective solution for large scale projects.
Inaccurate Parts – It is difficult to obtain precise tolerances with vacuum forming, which can lead to inaccuracies in the finished product.
Conclusion
Vacuum forming is a manufacturing process in which a thermoplastic material is heated and formed to a specific shape in a mold and trimmed to create a usable part or component. Vacuum forming is an economical, quick and reliable process for creating large scale, intricate parts and components in prototype, low volume and high volume production rates. Vacuum forming offers a number of advantages over traditional fabrication processes, including strength, light weight, efficiency, cost, and environmental friendliness. However, there are some drawbacks, such as limited size and accuracy, that should be taken into consideration.
