In part one of this two-part blog series, we went over some of the basic differences between custom injection molding and compression molding for plastics. These are two of the most common processes for plastic manufacturing, and while they are similar in a few minor ways, they also differ in some other important ones that help define which is chosen for a given application.

At EnviroTech Custom Injection Molders, we offer comprehensive custom injection molding services, from product design consultation all the way through engineering and finalization. In today’s part two of our series, we’ll look at how compression molding compares to injection molding, plus some of the limitations of compression molding that lead many manufacturers to choose injection molding for a number of applications.

Compression Molding Benefits

As we noted in part one, compression molding involves heating a mold and placing plastic inside it, then closing the mold and compressing the plastic using hydraulics to create the desired shape. This heating process is known as curing, and products must be allowed to cool before being removed from the mold.

Compression molding is similar to injection molding in that both processes are efficient and cost-effective. Compression molding is not quite as versatile as injection molding, but can still be used for a wide variety of applications. Generally, compression molding is often used for higher-volume projects where less detail and complexity is required – it can’t achieve the same level of precision as injection molding, unfortunately.

Compression Molding Applications

Compression molding isn’t used in quite the diverse range of applications as injection molding, but it’s still widely-used. It’s often utilized when strong, durable parts are required, such as in automotive areas, clothing fasteners, circuit breakers, plastic dinnerware, stove knobs and even body armor for law enforcement agents.

As we noted above, however, compression molding is not ideal for any product that requires particular detail or complexity. Its inputs don’t allow for the same level of specificity as injection molding, where far more customization is possible.

Limitations of Compression Molding

As we’ve noted multiple times in this series, the primary limitation of compression molding is its inability to produce complex parts. It’s also limited in terms of the size of materials it can produce – generally speaking, it cannot handle any diameter closure above 48mm.

In addition, finding proper vendors for equipment when it comes to compression molding can be much more difficult than the same process for injection molding. Finally, any tamper evidence for compression molding usually requires secondary operations, which is not the case with injection molding.

For more on the differences between custom injection molding and compression molding for plastics, or to learn about any of our custom plastic molding products, speak to the staff at EnviroTech Custom Injection Molders today.