The thermoforming process involves heating and molding a plastic sheet using air pressure and vacuum. In order to achieve the final product, thermoforming can use several different types of molds and processes.
To thermoform a plastic product:
- A sheet of plastic material is clamped into a thermoformer and sent into an oven for heating.
- Once it reaches the right temperature for processing, it’s pulled over or pushed into a mold with either vacuum or air pressure to form a part.
- The formed part is then cooled, removed from the mold and sent to the next station for trimming.
One of the most economical thermoforming technologies is vacuum forming. During the vacuum forming process, a vacuum pulls thermoplastic material against a mold to create a contoured surface.
When aesthetics are important, pressure forming is the best option. Pressure forming uses both a vacuum to pull thermoplastic material into the cavity of a mold and air pressure to push it tightly against the surface. The extra pressure allows the plastic to pick up precise detailing.
Thermoforming vs. Injection Molding & Rotomolding
The thermoforming process offers many advantages over other manufacturing processes for crafting plastic parts, including injection molding and rotomolding, which is commonly referred to as rotational molding.
To injection mold a plastic product, hot molten plastic is injected under high pressure between a mold cavity and a core. After the plastic cools and solidifies, the mold cavity opens and the part is ejected. Rotational molding is the process of creating hollow plastic products from flexible PVC, nylon, polymer resins, cross-linked polyethylene, high- and low-density polyethylene and urethane foam.
Advantages of Thermoforming vs. Injection Molding
- Design flexibility
- Time to production
- Lower tooling costs
- Cost-efficiency for smaller production runs
- Prototypes can be produced quickly and accurately
Unlike the thermoforming process, very large-sized parts become a problem to make using the injection molding process. For example, you wouldn’t make an injection molded canoe, but you can vacuum form one.
Tooling is the most important factor in manufacturing a quality thermoformed product. The right tooling can produce crisp lines, edges, texture and other detailing that stays consistent from piece to piece.
Compared to tooling for injection molded parts, tools for thermoformed parts are simpler to update or redesign. Replaceable inserts can add new styling features, logos, openings or other variations. That flexibility also means it’s simple to modify tooling when it’s time to redesign or update your thermoformed products. Injection molding tooling takes a long time to produce (anywhere from 12 to 16 weeks), whereas thermoforming takes six to eight weeks.
Advantages of Thermoforming vs. Rotomolding
- Tooling is less expensive
- More material options
- Tighter tolerances
- Greater thru-put for production
- Greater availability of resins
While rotomolding produces parts using minimal secondary processes, not every plastic material can be used to create parts. When selecting a material for your project, it’s important to consider the physical properties and suggested applications of the plastic sheet. In the thermoforming process, there are a multitude of thermoforming resins that provide just the right properties for your plastic formed product.
Our 3-Stage Plastic Thermoforming Process
Looking for a plastic forming solution for your new product? Joslyn Manufacturing can meet your specifications to facilitate cost containment, manufacturability and quality assurance. We combine industry expertise, innovative problem-solving and customer collaboration in our 3-stage plastic thermoforming process. Our team has the expertise to create innovative solutions in a wide range of industries and can aid in materials selection as well as part design.
If you’re interested in learning more about the thermoforming process and the advantages of thermoforming over other methods, contact us to speak with a plastic thermoforming professional.