Injection Molding vs Thermoforming 

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Injection molding and thermoforming are two of the most common techniques used to create cost-effective plastic components.

Injection molding uses high pressure to force molten thermoplastics into detailed cavity molds. Since each cycle can fill many molds, injection molding is extremely efficient, and its results are both precise and repeatable. Thermoforming also uses heat and pressure to mold plastic. However, it begins with a solid sheet of thermoplastic, which conforms to a molded tool when pressure is applied. While it has a low start-up cost, thermoforming lacks some of the benefits of injection molding. 

This article explores the advantages of each process to help you make the optimal choice for your next thermoplastics project.

Thermoforming vs. Injection Molding Cost

The cost differences between thermoforming and injection molding are largely due to differences in tooling costs. The molds used for thermoforming tend to be less complex, and because the process uses lower pressure levels, they can be made from more affordable materials. Together, these factors mean that thermoforming tend to require a lower initial investment than injection molding. 

At the same time, while injection molding requires more money up-front, the tooling is extremely durable and can be reused across multiple high-volume runs. The same is not true of thermoforming molds, which will need to be remade after a certain amount of wear. This means that injection molding is often more affordable in the long term, especially for clients with high-volume requirements.

Thermoforming vs. Injection Molding Lead Times

Differences in tooling similarly affect the lead time for thermoforming and injection molding. Due to their higher complexity, injection molds typically take longer to create than thermoforming dies. It is not uncommon for injection molds to require a prolonged design and prototyping phase before production begins. 

The first time you order injection-molded components, the lead time will likely be longer than if you had chosen thermoforming. However, injection molding is also known for its high-efficiency thanks to multi-cavity molds and the potential for automation. This means that, after the first run, lead times become much more favorable for injection molding.

How to Choose Between Thermoforming & Injection Molding

When considering injection molding vs. thermoforming, it is important to consider how the methods' advantages relate to your project parameters. 

Thermoforming

Thermoforming's key advantages include:

• Short development cycle. Thermoforming dies are relatively simple to produce, so manufacturers can move from concept to prototype very quickly.
• Adaptability. The ability to quickly and affordably develop tooling makes it easy for manufacturers to adjust designs on the fly. Making changes to an injection mold is much more involved.
• Aesthetic choices. Thermoforming makes it easy to achieve varied colors and textures, and finished components are compatible with many finishing processes to further expand the options.

In general, thermoforming is preferable to injection molding for large parts, or for simple designs at low production volumes. If the product has complex features, or if you need more than 3,000 pieces, injection molding is likely the better option. Still, thermoforming is a fast and cost-effective choice for many components, including:

• Automotive & Aerospace Parts
  • Dashboards
  • Interior panels
  • Bumpers
  • Air ducts
  • Seat components
  • Galley equipment
  • Window shades

• Equipment for Homes & Offices
  • Housings for printers and copiers
  • Electrical panels
  • Wall panels

• Medical Equipment
  • Imaging systems (MRI, CT, and X-ray housings)
  • Mobility aids and assistive equipment

• Construction
  • Tool cases
  • Equipment housings
  • Exterior and interior panels

Injection Molding

There is some overlap in the range of projects that can be accomplished with thermoforming and injection molding. However, the chief advantages of injection molding benefit a different set of products. These strengths include:

• Complexity and precision. Injection molds are ideal for achieving intricate geometries and sharp features. They also enable tighter tolerances than thermoform dies.
• High efficiency. A single injection molding cycle creates multiple parts with the exact same features.

Based on these advantages, injection molding is best used for small or complex parts, or those requiring tight tolerances. It is also the better option for large or recurring orders. Typical applications include:

• Aersospace & Automotive
  • Gears
  • Panels
  • Turbine housings and blades
    
• Construction Components
  • Fasteners and fittings
  • Handles
  • Locks
  • Building accessories
  • Hand tools

• Medical Components
  • Surgical kits
  • Fittings for diagnostic equipment

• Retail Supplies
  • Elements for point-of-purchase displays
  • Packaging elements

Injection Molding Services from Advanced Prototype Molding

Injection molding and thermoforming are both effective, versatile techniques with many advantages. There is no single best choice that suits all projects. Instead, you should consider project parameters and constraints to identify the best option. 

If your project involves small elements, complicated features, or high volumes, injection molding may be the right fit for you. As an ISO 9001:2015-certified manufacturer, Advanced Prototype offers reliable injection molding services, including options for urethane castings and RTV molds. To learn more, contact us or request a quote today.