Rubber Extrusion

What Is Extrusion Process?

Extrusion is a unique manufacturing technique where a die manipulates material to a definite shape. In this case, you can transform rubber into continuous shapes using an extrusion die.

When making extruded rubber parts, the tooling system here is the die.

Extruding Rubber Parts Benefits

• Economical way to manufacture rubber parts due to slightly low production costs
• Versatile product that can produce rubber parts in a variety of shapes
• Durable and long-lasting parts
• Reduces material wastage
• Rubber parts are lightweight
• Suitable for making uniformly shaped rubber parts
• Extruded rubber parts are flexible
• Better performance in various temperature conditions

Choosing Rubber Materials for Extrusion Process

Rubber materials come in different properties.

As a rule of thumb, you must understand your application requirements before choosing rubber for the extrusion process. Some application requirements may include;

• Pressure rating requirements
• Temperature resistance requirements
• Vibration
• Exposure to corrosive environments
• Shear forces
• Abrasion specifications
• Compression requirements
• Electrical insulation requirements

Let’s explore common types of rubber materials:

How Rubber Extrusion Process Works

Extruding rubber is a systematic process involving several processes. The complexity or number of stages will depend on the rubber part designs.

Ideally, the process entails:

• Designing extrusion die
• Preparing rubber material or compounding
• Heating
• Kneading
• Rubber material pressurization
• Extruding rubber
• Vulcanizing rubber

Let’s look at these processes in detail:

Step 1: Design Rubber Parts

Knowing the exact rubber profile you wish to extrude is very important. It will help you design a suitable tooling system for your rubber part.

It doesn’t matter whether you want standard or custom rubber extrusions. You will design a suitable die for the extrusion process.

In short: Have suitable extrusion die for the rubber material.

Step 2: Prepare Rubber Material for Extrusion Process

You must understand your rubber application requirements. With this information, you will know the various performance properties of extruded rubber products.

For example;

• Heat-resistant gaskets in the food industry – go for silicon rubber
• Hoses with excellent aging resistance – choose Neoprene rubber

However, choosing rubber material for extrusion is never enough. You must prepare the rubber by adding various additive or subjecting it to certain processes.

This way, you will improve the intrinsic properties of rubber material. Usually, the process is called rubber compounding. That is, you can add:

• Fillers
• Stabilizers
• Vulcanizing/curing agents
• Special ingredients

Let’s summarize why these four elements are critical when extruding rubber:

Step 3: Rubber Extrusion Process

First, feed the rubber material prepared in step 2 above in the hopper. From here, the rubber material will move to the processing changer.

Second, configure and switch on the machine. The shearing screws will begin to rotate.

As the screw rotates, they transform the rubber to a pliable state. There are two screw designs:

• Single screw
• Twin screw

So, which options should you choose for extruding rubber parts – let’s compare:

Note: For a simple rubber extrusion process, you can choose single screw systems. It is affordable and easy to control.

At times, you may use rubber strips in the extrusion process.

Third, as the rubber moves through the conveyor system, the action of the screws heats the rubber. Consequently, the rubber will be ready for extrusion. At the same time, the screw’s action subjects the rubber material to pressure.

Finally, the screws will force pliable rubber material through a die. The rubber material exits the die (tooling systems). It will conform to the shape of the die system.

The extruded rubber parts will leave the die system. You will vulcanize rubber making it harden. You can shorten the rubber vulcanization timeframe using activators and accelerators.

Again, before rubber vulcanization starts, you may maintain the temperature between 140°C and 160°C.

Your extruded rubber product will be ready for secondary operations and quality inspection. Depending on the specific features you may want the rubber parts to have, you can:

• Cut to size
• Splice
• Drill
• Coat, etc.

Although the processes may vary slightly, generally, this is how to make rubber extrusions.

How Plastic Extrusion Compares to Rubber Extrusions

Ideally, the extruding two materials are virtually the same. What differs mainly is the applications and property specifications.

Take a look:

However, there are instances where you can extrude both rubber and plastics. Through co-extrusion you can easily make parts with both rubber and plastics.

Such components have unique properties such as soft and rigid.

Remember, co-extrusion is a sensitive process that requires engineers to consider many variables such as:

• Temperature for co-extrusion process
• Production cost
• Adhesive
• Recyclability
• Color

Applications of Extrusion in Rubber Parts Production

Extruded rubber products are available in many configurations. Common applications are:

Ideally, you can use rubber materials in many applications such as:

• Piping sealing systems
• Automotive part assembly
• Vibration reducer applications
• Window and door sealing systems
• Pressure systems
• Storage systems

In short, from aerospace, food processing, chemical petroleum, to agricultural industries, rubber parts play an integral role.