There are two main processes used to make plastic molds: injection molding and thermoforming. Though similar, both techniques offer unique features and benefits, making each method ideal for specific applications.
Injection molding involves injecting molten liquid polymers into a mold at high temperature and extreme pressure. Once the mold cools, the newly formed plastic parts are released. Thermoforming, on the other hand, involves heating thermoforming plastic sheets and forming them to a mold’s surface.
Key Differences Between Injection Molding and Thermoforming
There are several key differences between plastic injection molding and thermoforming. First off, each process can handle different types of production volumes. Typically, plastic injection molding is used for large, high-volume production runs, while thermoforming is used for smaller production quantities. And whereas the injection molding process usually produces parts as finished pieces, thermoforming often requires secondary finishing processes to create the desired aesthetics.
Injection molding is ideal for creating smaller, more intricate and complex parts, as it can accommodate difficult geometries and tight tolerances — sometimes less than +/- .005, depending on the material used and the thickness of the part. Thermoforming, on the other hand, accommodates simpler geometries and larger tolerances, making it ideal for larger parts with more basic designs.
And finally, while injection molding can be used for a wide variety of plastics, thermoforming is more limited in terms of what types of materials can be worked — particularly when dealing with stronger materials.
Which Process Is Best for Me?
For some industries and applications, both processes may be used for the manufacture of plastic parts. But many industries turn to a specific method based on the unique attributes of the project at hand. To determine which process is best for your plastic molding job, it’s important to carefully assess the unique characteristics and requirements of your project.
For most projects requiring higher production volumes, very complex or detailed designs, short lead times, or automated programming to decrease manufacturing costs, it’s best to use injection molding. The injection molding process can accommodate all of these requirements, accurately producing large runs of high-precision parts in a timely, cost-effective manner.
Alternatively, thermoforming is ideal for projects requiring smaller production quantities, lower tooling costs, or parts with color and texture. For larger parts with simplified designs, thermoforming offers short lead times and a wide array of aesthetic options.
Whether you’re working with plastic pellets for injection molding jobs or sheets of plastic for thermoforming, both methods ensure great reliability and high quality. The best option for a specific job will depend on the unique requirements of the application at hand.