Injection Molding is the most cost-effective way to make plastic products at scale. This plastic manufacturing process takes plastic resin, melts it into molten material, and injects it into a “mold tool.” After cooling, plastic manufacturers eject the formerly molten plastic material from the injection unit, creating complex three-dimensional shapes with a smooth surface finish. This process can rapidly repeat hundreds or thousands of times, amortizing the cost of the mold tool and driving down costs as one orders more plastic products. Since the same mold tool is used for each part, and the plastic pellets used for plastic molding are so cheap, this plastic manufacturing is well suited to produce affordable parts of consistent quality.

The extrusion process is used to create continuous linear bars. After molten material is sent through an extrusion machine and comes out the other end of a two-dimensional die opening,  creating rod-like shapes with complex cross-sections, outer shapes, and even inner voids. These complex shapes of long bar, often 100 or 1000 feet long, are typically cut with a band saw and can be shaped and post modified or placed in an assembly.

Benefits and Disadvantages

There are some similarities between the injection molding process and the extrusion process; Both injection molding and extrusion are affordable options if you want to create thousands of the same parts. But, before ordering, one should keep in mind the relative advantages and disadvantages of each method.