An In-Depth Look at Costs, Time, and Features of Thermoforming Vs. Injection Molding

Since 1988, our plastic fabrication and manufacturing company has worked with customers throughout the Southeast and Mid-Atlantic, providing the custom parts and components used in a variety of industries, including automotive, medical, refrigeration, and telecommunications. When our team of designers and engineers sit down with a customer to discuss the design and production of a new component or product, one of the most important decisions is choosing which manufacturing method is best – thermoforming vs. injection molding.

That’s a question that we get asked frequently – “Which is better, thermoforming vs. injection molding?” The short answer is “Neither” because each project is different, and we have to look at a variety of variables that affect which method of production will get you the lowest cost and  shortest lead time without sacrificing accuracy and quality. To help you understand not only the pros and cons of thermoforming vs. injection molding, but also the variables we look at when choosing a method, we’re providing an in-depth look at both ways we manufacture custom plastics.

Understanding Thermoforming

When we refer to thermoforming, this method requires heating a sheet of thermoplastic to where it is flexible and malleable, then forming it around a custom designed tool. The single sided tool is generally made from aluminum, meaning it is quick to create and made from less expensive materials, reducing the initial costs.

At Advanced Plastiform, Inc., we offer three different types of thermoforming to ensure an accurate design that is the most cost-effective to our customers.

Vacuum Forming

The vacuum forming process involves pressing the heated plastic sheet to the mold and vacuuming out the air to form a tight fit against the mold. It’s the quickest, and also most cost-effective way to form plastics, but because it uses the least amount of pressure, it’s best for large pieces that don’t require heavy detailing, sharp corners, or sharp angles.

Pressure Forming

Plastic pressure molding works in an opposite way to vacuum forming. Once the plastic is heated and fitted around the tool, it’s blasted with highly pressurized air to force the plastic against the tool, getting the sharper corners and details that vacuum forming can’t.

Twin Sheet Forming

Twin sheet forming uses two sheets of heated plastic are pressed against one mold from opposite sides and fuse where both sheets meet. Often used to make air ducts, vending machines, bed liners, and hollow or double-walled industrial products, this method requires care and precision to ensure the pieces are lined and fused with total accuracy.

Understanding Injection Molding

The injection molding process involves thermoplastic pellets to be heated to liquid and injected into a custom, 3D mold using high pressure. This forces the melted plastic into every void in the double-sided mold, ensuring a highly accurate finished product, Injection molding is best used to create components with variable thickness, intricate details or ridges, and sharp corners and angles, especially for smaller plastic pieces.

Cost of Thermoforming Vs. Injection Molding

The up-front cost of thermoforming is generally much less expensive than injection molding. Much of this is due to the cost of tooling used in thermoforming vs. injection molding. Because the pressure used in thermoforming is not nearly as great as injection molding, most tooling can be made from aluminum, a cost-effective material. Additionally, a single sided tool is much easier and less expensive to make than the molds required for injection molding.

Injection molding requires a much heavier, dual-sided mold that can withstand up to 530 tons of pressure, so the molds are made from more expensive materials, including steel, heavier aluminum, or beryllium-copper alloy. However, once the tooling for injection molding is made, it can be used repeatedly, making this more cost-effective for large orders or repeat order fulfillment.

Lead Times with Thermoforming Vs. Injection Molding

Thermoforming does often have a much shorter lead time than injection molding, and again, this is generally due to tooling design and creation. Designing and prototyping a single-sided aluminum tool is much quicker than the process to create a heavy, double-sided 3D mold used in injection molding. At API, lead times for thermoforming, including design and development all the way to delivery, are generally around 14 weeks. Injection molding, on the other hand, takes up to 20 weeks due to the tooling design and creation.

Again, tooling for injection molding is a one-time factor – once it’s in use, it can continue to be used, so after the initial run, lead times and per-unit costs are significantly reduced.

Choosing Thermoforming Vs. Injection Molding

Like we said, one method is not better than the other, choosing thermoforming vs. injection molding really is about which one is better to get the most accurate finished plastic at the lowest cost in the shortest amount of time.

Choosing Thermoforming

Generally, thermoforming is best for these variables:

  • Larger plastic pieces are needed or consolidating multiple components into a single piece
  • Smaller orders under 3,000 pieces or a one-time run
  • Final product doesn’t require complicated design, varying thickness, sharp angles or corners

Commonly thermoformed plastics include vehicle dashboards, bathtubs, shipping trays, and freezer liners.

Choosing Injection Molding

Generally, injection molding is best for these variables:

  • Smaller plastics are needed
  • Large orders or frequent fulfillment is needed
  • Component is highly detailed, requires variable thickness, sharp or crisp corners and angles

Examples of plastics created through injection molding include dials and knobs on cars, packaging, and bottle caps.

Contact Advanced Plastiform, Inc. Today

Because every project is unique, determining if your custom plastics should be manufactured using thermoforming or injection molding is best determined when you work with an experienced team of engineers and designers. At Advanced Plastiform, Inc., our team is with you every step of the way, assisting with design, creating a prototype, selecting the best method of manufacturing, and even providing inventory management solutions if needed.  When you are ready to get started with your custom pressure-formed or injection molded product, contact Advanced Plastiform. Inc. API offers high quality, custom manufactured components to companies in North Carolina, South Carolina, Georgia, Maryland, Pennsylvania, Tennessee, and Virginia.

Contact Advanced Plastiform, Inc.

Please contact us today by calling 919-404-2080 or filling out our form below to discuss your custom plastic manufacturing needs.
  • This field is for validation purposes and should be left unchanged.

Request a Quote

  • This field is for validation purposes and should be left unchanged.