Silicone rubber extrusion is one of the most used rubber product-making processes. This method has been widely used in factories since the 18th century. Silicone rubber extrusion generally shapes silicone and gives it a continuous length.
The machine used in this process is called an extruder machine. It has a central chamber, a hopper, and a die opening. The process first takes the raw material through a hopper. Then the screw inside the main chamber pushes it forward. There’s a heating chamber that melts or smoothens the silicone. Melting the silicone helps create shapes according to the shape of the die.
This method produces flexible, robust, and heat-resistant silicone parts. It is simple, affordable, and creates perfect silicone profiles—extrusion is becoming increasingly common.
Extruded silicone products have many applications. One of the most popular products is silicone rubber seal strips. This product is widely prevalent for sealing machines, boats, and even in your car. Other products are Silikonplatten, tubes, and gaskets.
This article mainly focuses on how these extruded silicone products are made. You will go through every step followed in factories. Note that this process might be similar to other rubber types.
How are Silicone Extrusion Profiles Made?
Silicone is a highly flexible, heat-resistant, and durable rubber. One of the best things about silicone is its temperature rating. It typically melts at 80 to 220 degrees Celsius. So you can realize that your silicone rubber extrusion process must be able to handle it. Most silicone extrusion manufacturers follow a few steps. These steps are all professional level.
Step #1 Preparation
Preparation is the first crucial step in the silicone extrusion process. Your application determines the silicone substance you use. Extrusion uses two forms of silicone: solid and liquid. People like solid silicone because it is long-lasting and heat-resistant.
Designing the extrusion die comes next and is also absolutely vital. You must ensure it is built with excellent tool steel and accuracy. Usually, the die shapes and sizes of the finished extruded silicone product. To make a new product, you must create the custom dies first.
The next important thing to do carefully is to set up the extrusion equipment. To prevent contamination, you must clean the machines before the actual process. You should also focus on expert calibration of the device. Once everything is prepared, you can start the process.
Step #2 Material Mixing and Compounding
Step #1 includes this one as well. We included it separately since it is among the most critical stages in the silicone extrusion process.
As you know, extruded silicone profiles come in various colors. Also, some profiles are strong, while some are highly heat-resistant. You can determine what raw materials you must use to get these properties at this stage.
You can use colorants, stabilizers, and flame retardants when making the mixture. Colorants generally give the material its look. Stabilizers improve the durability of the extruded silicone products. However, flame retardants are crucial for safety in many applications.
This whole process is done in a controlled environment. Some call it a milling process, while others call it a compounding process. Whatever the name, it involves homogenizing the silicone mixture.
Step #3 Silicone Rubber Extrusion Process Setup
After preparation, you must apply the appropriate setting to the production line for silicone rubber extrusion. An extruder usually has several components: a hopper, barrel, and dies. These three are the main components, though. There are other critical parts as well.
When you put the raw or compounded silicone into the hopper, it goes directly into the barrel. Inside it, a screw pushes them forward.
Note that every factory operates the extrusion process in a controlled environment. One critical part of this process is temperature adjustment. Therefore, you must check the working temperature. At the same time, pressure checks are also necessary. Finally, you can adjust the speed. Note that the appropriate speed depends on the thickness and profile shape.
Note that you must synchronize the above factors properly. If not, the final product might not match the design. Therefore, in factories, experts always balance them. It typically helps them ensure the quality of the silicone extruded profiles.
Step #4 Heating and Silicone Extrusion
Let’s come to the actual process. The silicone rubber extrusion operation can begin once everything is ready. Feed the hopper either raw or processed silicone rubber first. Gradually, the hopper will feed them into the extruder machine—where a screw exists. This screw’s primary use is to advance the material.
This extruder machine usually has a way to control the heating. The temperature needs to be high enough to melt the silicone rubber. Why is melting or softening silicone necessary? There are several reasons. The important one is that it helps silicone pass smoothly through the die. The silicone rubber also needs to be continuously heated to maintain its features.
Step #5 Cooling and Post Curing
Once the newly shaped silicone rubber comes out of the die, it needs cooling. Note that the extruded silicone profiles are long and continuous. Therefore, the cooling chamber must be long enough to cool and harden the extruded silicone.
There are various types of cooling methods. The process can be done by air, water, or passing the profile along a conveyor system. Whatever the process, the goal is to stabilize the shape quickly.
As we mentioned earlier, many silicone-extruded products exist. Some are strong, while others are flexible. Again, some can endure high heat, while others cannot. So, after cooling your silicone extrusion profiles, they might need a post-curing method.
A post-curing method is typically a heating process. Here, the cooled profiles are further heated to gain the exact properties as needed. Note that this heating process must be accurate; otherwise, your profiles may be defective. In general, the post-curing method improves the durability and strength of the material. Also, it maximizes flexibility. Note that this process improves the high heat resilience of the silicone extrusion profiles.
There is another benefit to the post-curing method. It mainly reduces the risk of compression setting. FYI: Compression set is the ability of a material to return to its original shape after being compressed.
If you don’t do the post-curing, the silicone rubber extrusion products may wear out quickly under pressure. Therefore, every factory ensures proper control of both cooling and post-curing.
Step #6 Cutting and Final Processing
After completing the cooling and post-curing process, you can cut the profiles into various lengths or roll them up to ship in bulk. Machines usually do this work, and because of this, they always have consistent cutting quality.
After cutting, your silicone rubber extrusion profiles may need extra finishing. This post-processing generally improves your product’s look. People mostly use methods like surface treatments, trimming, and co-extrusion.
Surface treatments mean treating or processing the material’s surface. For silicone rubber extrusion, you can smooth it or add a protective coating. Trimming, on the other hand, cuts the excess part from the profile. Sometimes, you may also need co-extrusion or multi-extrusion processes. You will mostly need it for reinforced or multi-layer extrusion silicone profiles.
Step #7 Quality Control
In this step, the factory engineers check whether the product meets the standards. During this step, different testing methods may be used. The first is to examine the profile’s measurements. Second, surface checks look for cracks, air bubbles, or unevenness. Third, different tests check the profile’s stretch and tensile strength. Other tests are also done, such as chemical protection tests.
Once tested, the factory generally creates a quality certificate, which is later delivered to the customer. Some standards, such as FDA and ISO, are followed when manufacturing.
Step #8 Packaging and Distribution
Customers usually check a few things during delivery. The transportation and compliance paper lists the industry standards. The quality certificates show that the product is of good quality. High-quality packaging ensures that the shipping is safe, especially for foreign delivery. Finally, they check the quantity of the delivered product.
A reputable factory like Seashore Rubber always ensures the customer meets these requirements. They also ensure the packaging and distribution are done accurately and safely. The manuals are provided so the customer can understand how to use them properly.
Custom Silicone Extrusion at Seashore Rubber
Custom silicon extrusion is a process of making unique profiles or designs. In other words, there is no product replacement or standard dies for custom products. Custom silicone rubber extrusion is becoming increasingly popular as the need for unique tools has increased dramatically.
Custom silicone rubber extrusion has several benefits. First, it can meet diverse customer needs. Second, it offers you more precise solutions and design versatility. Although the initial cost might be higher, you can get an active market response.
At Seashore Rubber, you can get custom silicone extrusion services. The company provides high-quality silicone profiles for every industry. All you need to do for custom products is provide your project’s data. If your design is ready, you can save time and investment. It’s also okay not to have the design ready; their expert engineers can create custom dies based on your data.
Get in Touch With Us! Ready to start your project? Contact Seashore Rubber today. We’re eager to help with your custom silicone extrusion needs.