• March 2, 2026
Choosing the right plastic manufacturing process can make or break your project’s success. Whether you’re producing 500 units or 50,000, the decision between Reaction Injection Molding (RIM), injection molding, and thermoforming comes down to understanding your part’s design requirements, production volume, and budget. At AdvancTEK, we offer all three processes under one roof — giving us a unique perspective on when each method delivers the best results.
We sat down with Patrick McAllister, one of our senior manufacturing experts, to break down the practical differences between these processes and help you determine which one is right for your next project.
Understanding the Three Processes
Injection Molding
Injection molding is one of the most widely used plastic manufacturing processes. Molten plastic resin is injected under high pressure into a precision-machined steel mold, producing complex, high-quality components with tight tolerances. Parts often feature both “A” and “B” side design elements that can be functional, structural, or aesthetic. With presses ranging from 65 to 3,500 tons, AdvancTEK handles everything from small precision components to large structural parts.
Reaction Injection Molding (RIM)
RIM combines two reactive components that are mixed and injected into a mold under low pressure. As the polyurethane reacts, it fills the mold cavity and cures to form the finished part. This process allows for extensive material customization and significant design flexibility — similar to injection molding — but with a substantially lower tooling investment.
Thermoforming
Thermoforming involves heating an extruded plastic sheet and drawing it over a mold, then applying vacuum pressure to pull the heated plastic into its final shape. Secondary trimming processes create the final geometry and incorporate installation and design features. AdvancTEK can handle sheet sizes up to 6′ x 8′, making it well-suited for large-format components.
Key Factors in Choosing the Right Process
When to Choose Each Process
Choose Injection Molding When:
- You need high production volumes with consistent repeatability
- Your part design requires tight tolerances and complex B-side features
- Cost per unit is a primary concern at scale
- You need minimal waste and fast cycle times
“With Injection molding, materials are introduced to the mold under immense pressure. A large amount of detail and complexity can be incorporated into these parts. Action can be incorporated into the tool design to allow for die lock features to be designed into the part.”
— Patrick McAllister, AdvancTEK
The images below show a real injection molded door panel—the A-side (exterior-facing) and B-side (interior with structural and attachment features)—demonstrating the level of complexity injection molding can achieve.
Choose RIM When:
- You’re producing large, lightweight parts that require a high strength-to-weight ratio
- Your project calls for low- to mid-volume production (500–10,000 units annually)
- You need design flexibility with complex geometries and varying wall thicknesses
- Tooling budget is a concern—RIM offers significant cost savings over injection molding tooling
- Your application requires superior acoustic or thermal properties
“RIM is an especially attractive option when you need the design flexibility of injection molding but the tooling investment doesn’t justify the production volume.”
— Patrick McAllister, AdvancTEK
Choose Thermoforming When:
- You’re manufacturing large-format parts where reduced tooling investment is essential
- Your part geometry is relatively simple and doesn’t require extensive B-side molded features
- You need rapid prototyping with low-cost wood or epoxy tooling
- Your application includes roofs, fender liners, storage bins, fascias, or enclosures
“Thermoforming delivers the best results with simple geometries that don’t require a lot of action in the tooling. B-side design features will require a secondary operation, like bonding, to attach — they cannot be molded directly into the part.“
— Patrick McAllister, AdvancTEK
The AdvancTEK Advantage: All Three Processes Under One Roof
Most plastic manufacturers specialize in a single process. That means when you bring them a project, they’ll recommend the process they offer — whether it’s the best fit or not. AdvancTEK is different.
With injection molding, RIM, and thermoforming capabilities across our facilities in Concord, NC; Dublin, VA; and Saltillo, Mexico, we evaluate every project on its own merits and guide you to the right manufacturing method. Our team doesn’t just recommend a process — we help you understand why it’s the right choice for your specific volume, part design, and budget requirements.
“Our ability to offer various molding processes gives us a competitive edge. We can guide customers to the right process based on their design and requirements rather than trying to force-fit a project into the only process we have.“
— Patrick McAllister, AdvancTEK
Combined with IATF 16949 and ISO 14001 certifications, in-house design and engineering support, and over 35 years of manufacturing experience, AdvancTEK is uniquely positioned to be your single-source partner for custom plastic manufacturing.
Not sure which process is right for your project? Our team can help. Contact AdvancTEK today to discuss your requirements and get a quote.
