RPM Industries LLC
Rubber Compression Molding

Brief Introduction to the Workings of Rubber Compression Molding

Rubber compression molding is a method used for molding various types of rubber. With this method, the finished product is in a specific rubber mold design that matches the customer’s specifications. In other words, the mold is what defines the shape, size, and detailing of parts and components that the customer will use for their products that ultimately go out to consumers or get used for their own manufacturing processes.


To better understand how this process works, the compression molding process steps are provided below.


To start with, this is a closed mold process in which high-pressure is applied. Typically, this method is most beneficial for low to medium production volumes of larger parts; the reason is that these parts do not require perfect finishing or tight tolerances. To complete the process, machinery known as a Compression Molding Press is used. In most cases, this machinery is driven by hydraulics.


With compression molding, the mold is usually preheated. Then, the uncured rubber material is pre-formed to a controlled shape and weight. This pre-formed piece of rubber goes directly into the mold cavity, the mold is closed, and the rubber is then compressed between two plates; this causes the material to flow into the cavity, filling it up. Under high pressure that is increased to activate the cure system in the rubber, the material remains in the mold. Once the optimal level of curing is reached, the cycle ends. At that time, the finished part or component is ejected from the cavity.


Advantages and Disadvantages of Compression Molding

One of the biggest advantages to compression molding is that it’s a very cost-effective method. In addition, this machinery can accommodate large molding sizes and changeover between different molds is quick, resulting in shorter production runs. Another advantage of using this molding method is that the machine has no tooling features. Being void of spruces, runners, or gates also helps speed up production without compromising the quality of the finished product.


Although there are plenty of reasons for using compression molding for rubber, there are some disadvantages. For instance, both the loading and unloading of the output must be done manually, which in turn, increases labor costs since this requires distinctive skill. In addition, because compression molding is not as precise as other molding processes, including injection molding, there is more product waste.


RPM Industries, Inc. is a leading manufacturer of rubber compression molded products and more. Please visit our website to learn more about what we offer or you can contact a team expert by phone.