Understanding the Rubber Injection Molding Process

Rubber injection molding is an efficient technique for manufacturing precise rubber parts and rubber-to-metal bonded components. It creates products with faster cycle times than transfer or compression molding. In addition, due to its advantageous qualities, it is widely used in various industries, such as the automotive, food and beverage, medical, electronic, and agricultural sectors.

The rubber injection molding process started in the mid-1960s after the successful modification of the plastics method. This procedure involves heating the rubber and exerting greater pressure per square inch on the cavity surface.

In this article, we will elaborate on the basics of the rubber injection molding process and how it works.

What Is Rubber Injection Molding?

The rubber injection molding process molds uncured rubber by injecting the raw material into a metal mold chamber. It provides precision and efficiency not typically observed in other rubber manufacturing processes. It is also suited for applications utilizing compounds with quicker curing durations.

Here are some of the common applications and uses of rubber injection molding:

• Bumpers
• Bushings
• Diaphragms
• Grommets
• Isolators
• Mounts
• O-Rings
• Pads
• Plugs
• Seals
• Suction cups
• Washers

What Are the Components of the Rubber Injection Molding Process?

Like any other methodologies, the procedure begins with material preparation. One advantage of rubber injection molding is that it allows the use of different varieties of rubbers.

The following are the most frequently utilized materials in the manufacturing industry:

• Butyl
• EPDM
• Fluorocarbon
• Fluorosilicone
• Hydrogenated nitrile butadiene
• Natural rubber
• Neoprene
• Nitrile
• Silicone
• Styrene-butadiene
• Urethane

In addition to the raw rubber material, an injection molding machine or press is required. Common components include an injection ram, a heating system, and a hopper. Also called platens, they support the molds used to shape the components.

Injection molding machines or presses are graded by their tonnage, indicating the amount of clamping force the machine can exert. Tonnage can range from less than 5 tons to more than 9,000 tons, with very few manufacturing operations employing the higher amounts.

How Does the Rubber Injection Molding Process Work?

Rubber injection molding starts with the bulk mixing of raw rubber, followed by its stripping into continuous lengths. Next, they are fed through a screw into a barrel containing a predetermined quantity of rubber material. The screw then preheats the material before being injected into the cavities. This reduces the substance’s viscosity, allowing it to flow freely into the cavities.

The rubber stock plasticizes to the desired temperature while heating. Then, the plasticized rubber material is injected into a heated, high-pressure mold chamber. Using a runner and a gate system, heat and pressure initiate the curing of the rubber compound, ultimately vulcanizing it. Once the required level of cure is achieved, the rubber is allowed to cool and harden in the mold. Lastly, the pieces are ejected from the mold in preparation for the next cycle.

Jefferson Rubber Works for High-Quality Rubber Injection Molding Solutions

At Jefferson Rubber Works, we combine industry experience with cutting-edge technology to provide customized solutions and services at affordable costs and unmatched speed and precision. We can also assist you with component design, prototype, manufacture, finishing, and assembly, so you do not need to collaborate with many companies for a single project.

Contact us today to find out more about our services and solutions. You can also request a quote, and we will be happy to assist you with your needs!