Silicone rubber calendering is an important step in today’s material fabricating processes. It is important you understand the entire process and equipment you need.
In this guide, you will find all information you need about this rubber calendering process.
Let’s dive right in:
Advantages of Calendering Silicone Rubber
There are many reasons why you should consider this silicone rubber fabrication technique:
- Allows for continuous and high-volume silicone rubber fabrication
- A versatile process that can produce rubber with different thicknesses, surface finish, and flexibility depending on the material grade
- Since silicone calendering takes place at rooms temperature, there is no need for any form of stabilization
- Easy to make continuous rubber sheets
Best Silicone Material for Calendering Process
Not all silicone materials are suitable for the rubber calendering process. Usually, this is due to their formulation which may not produce quality products.
Take for instance;
High-temperature vulcanizing silicone or high-consistency rubber (HCR) is a perfect material for the rubber calendering process. Of course, this is due to its molecules which are heavyweight and highly reactive silicone.
On the other hand, liquid silicone rubber (LSR) is not suitable for rubber calendering. It exists in fluid form making it virtually unsuitable for the calendering process. Therefore, you can use other techniques such as liquid silicone rubber injection molding.
Step-by-step Silicone Rubber Calendering Process
Silicone Rubber Calendering Process
Silicone rubber calendaring refers to a mechanical process. In this process, silicone rubber passes through a series of heated rollers. This result in high strength and uniform thickness sheet formation.
An option exists to add other materials in the composition to strengthen the properties of silicone rubber.
Step 1: Feeding
In this stage, the silicone rubber in the granules form remains within the silicone rubber calendering machine hopper. You can add up other materials to the hopper. The materials you add depend on the final properties you want to achieve in the end product. You can add the following materials to the silicone.
- Monofilament Blends
You can also change the proportion or percentage of the material you add to silicone rubber. From the hopper, they get into another component. This stage refers to feeding.
Silicone Rubber Calendering
Step 2: Mixing
The next step in silicone rubber calendering process is mixing. The materials from the hopper get transferred into the screw. This screw exists right below the hopper.
A screw mixer comprises a long hollow shaft containing a screw in either a clockwise or anticlockwise direction. These screws rotate throughout the shaft within a vessel.
The screw mixer homogeneously mixes the material and conveys the material in the forward direction.
You can also tweak the speed of the mixer, and it also depends on the thickness of the material composition. If it gets mixed quickly, then you can increase the speed. If the material is thicker, you can decrease the rate to give more, resulting in a homogenous mix.
Step 3: Conveying
Conveying is the function of a screw mixer. It conveys the silicone rubber composition to the steel rollers. The number of rollers that exists in a machine varies. Some contain three, and some have more than three. When it is conveyed to the roller, the next stage begins.
Step 4: Heating & Extrusion
Calendering Process for Silicone Rubber
The heat mainly comes through the steel rollers. The heating element is within the rollers. You can control the temperature setting as per requirement. This heat causes the material to pass through the rollers easily.
The roller then causes the material extrusion. The space between the rollers determines the end thickness of the sheet. You can control the thickness of the material better by tweaking the distance between consecutive rollers.
The clockwise and counterclockwise rotation of the roller leads you to the homogenous, uniform, and high-strength sheet.
Step 5: Embossing
After the heating and extrusion through several series of rollers now come embossing. You can put on the logo, message, or any precautions by embossing. This technique creates a noticeable raised pattern from the surface of the sheet.
By doing this, you can take branding to the next level. An option exists to create the custom logo through embossing to personalize the silicone rubber sheet.
Step 6: Cooling
After the embossing has ended. Now you need to place the sheet to allow it to cool down. As the cooling proceeds, the properties of the material become strengthened. Cooling is essential because, without cooling, you can experience deformation and non-uniformity in the end product.
Step 7: Discharging
In the end, stage, there comes discharging. The sheet from the silicone rubber calendering process comes out from the machine. Now it is ready to ship anywhere you want.
Applications of the Silicone Calendering Process
When it comes to applications, by calendering silicone, you can make many products including:
- Ceiling covering
- Wall covering
- Shower curtains
- Flexible reservoir tanks
- Conveyor belt systems
- Seating upholstery in the aerospace industry
Of course, there are hundreds of industries benefiting from calendering rubber material.
Now you know everything about silicone rubber calendering. You can follow the above stages to carry out the process conveniently. Suppose you have any questions or want to share your thoughts on it. Feel free to comment in the comment section. We would love to hear your feedback and assist you in this regard.
Silicone Manufacturing – Source: LegenDay
Silicone Rubber – Source: Science Direct