Rubber calendering is a rubber processing process. A rubber compound is extruded and stretched between a pair of rollers. This forms a rubber sheet or film of the desired shape and thickness. This process is commonly used to prepare rubber products, such as tires, rubber sheets, and rubber flooring. Below are some basic concepts related to rubber calendering:
Rubber Mix: The first step in rubber calendering is to mix the rubber with other additives. These include vulcanizers, plasticizers, fillers, and pigments. These mixtures are often referred to as rubber mixes.
Calender: The calender is the key piece of equipment used for rubber calendering. It usually consists of a pair of large metal rollers. They have an adjustable distance between them to control the thickness of the rubber sheet.
Extrusion and Extension: In the rubber calendering process, the rubber compound is placed in the feed area of the calendar. Between the two rollers, it is extruded and extended by the rotation of the rollers. This results in the deformation of the compound. Ultimately, it forms a rubber sheet of the desired thickness and width.
Cooling: This cooling process ensures that the rubber does not overheat during stretching.
Table of Contents
Key role in industry and production
The rubber calendering process plays a key role in industrial production. It is particularly important in the manufacturing of rubber products.
Preparation of rubber materials: rubber calendering is one of the key steps in the preparation of rubber mixes. Mix the rubber with additives. Next, extrude and stretch it on a calender. This ensures the rubber mix has proper homogeneity and processability.
Improving rubber properties: The calendering process helps improve the physical properties of rubber. It enhances tensile strength, elasticity, and abrasion resistance. By controlling extrusion and extension, we can adjust the arrangement of rubber molecules. This changes the properties of rubber.
Formation of composites: In some applications, rubber can be combined with other materials to form composites. These composites have specific properties to meet different industrial needs.
Mass production: Rubber calendering is a mass-production process. It efficiently manufactures many similar rubber products. This is essential to meet industrial needs, reduce production costs, and ensure product consistency.
Adaptation to different applications: By adjusting the composition of the rubber compound and the parameters of the calender, you can flexibly produce rubber products adapted to different applications. This flexibility makes it essential in the production of rubber products.
Process flow of rubber calendering
Material Preparation And Mixing: First, prepare the rubber mixture by mixing rubber with various additives like vulcanizers, plasticizers, and fillers. Pre-treat the mixture to ensure the ingredients are evenly dispersed.
Basic Working Principle of Calender: The rubber compound is fed into the feed area of the calender, between two rollers. The rollers rotate to squeeze and stretch the compound, deforming it to the desired thickness, shape, and size.
Temperature and pressure control in calendering process: A calendering machine usually has an automatic control system. It can set and adjust parameters like temperature, pressure, and time according to production requirements. This enables intelligent and precise control of the calendering process.
Different types of rubber calendering applications
The rubber calendering process is widely used in various industrial fields. It produces various rubber products. This includes, but is not limited to:
Rubber products manufacturing industry: used to manufacture various rubber and plastic products. These include rubber sheets and rubber belts.
Chemical industry:used to manufacture rubber pipes, rubber seals, etc.
Electronic industry: used to manufacture rubber seals, rubber gaskets and so on.
Automotive industry: used in the manufacture of automobile tires, rubber seals, etc..
Construction material industry: used to manufacture rubber gaskets and other shrinkage materials.
Comparison with other rubber processing methods
Comparison with extrusion method
1. Difference in process principle
Rubber Calendering: Calendering is the process of forming a thin sheet of rubber compound by squeezing and stretching action between two rollers. The focus is on flattening and stretching in the horizontal direction.
Rubber Extrusion: The extrusion process is the process of forming a rubber compound into a desired cross-sectional shape by squeezing it through the screw barrel of an extruder, allowing it to pass through a die or extrusion head. More emphasis is placed on extrusion in the vertical direction.
2. Differences in the shape of the final product
Rubber calendering: the calendering process is commonly used in the preparation of flat rubber sheets, plates, etc.
Rubber Extrusion: The extrusion process is used to prepare rubber products with complex cross-sectional shapes such as sealing strips, tubes, and so on.
3. Different equipment organizations
Rubber calendering: The calender mainly consists of a pair of horizontal rollers that can adjust the distance.
Rubber Extrusion: The main component of the extruder is a spiral cylinder, which feeds the rubber mixture into the extrusion head by rotation.
4. Differences in product properties
Rubber Calendering: Due to the horizontal directionality of extrusion and extension, rubber calendering may result in higher tensile strength and elasticity.
Rubber Extrusion: The extrusion method is more suitable for products requiring a specific cross-section and shape, and is slightly inferior to calendering in terms of performance.
Comparison with molding method
1.Principle of the process
Rubber calendering process: Calendering is the process of forming a thin sheet of rubber compound by squeezing and stretching action between two rollers. The focus is on flattening and stretching in the horizontal direction.
Rubber Molding Process: Molding is the process of placing the rubber mixture in a mold, and through the action of pressure and temperature, the mixture fills the cavity of the mold, thus forming the desired shape.
2.Applicable products
Rubber calendering process: calendering process is commonly used in the preparation of flat rubber sheet, plate, and so on.
Rubber molding process: molding method is suitable for seals, o-rings and other rubber products with complex cross-section and shape.
Process control
Rubber calendering process: by adjusting the distance between the two rollers of the calender and the temperature, different thicknesses and properties of the rubber sheet are realized.
Rubber molding process: Process control involves the design and adjustment of the mold to ensure the accuracy and consistency of the product.
Production efficiency
Rubber calendering process: applicable to large area, relatively thin products and mass production.
Rubber molding process: suitable for small batch production, especially for products with high shape and size requirements.
Product properties
Rubber calendering process: due to the directionality of extrusion and extension, higher tensile strength and elasticity can be achieved.
Rubber molding process: can achieve more accurate product shape and size, performance is slightly inferior to the calendering method.
Comparison with injection molding method
1.Process Principle
Rubber Calendering: The calendering method involves forming the rubber compound into flat or slightly curved rubber sheets by squeezing and stretching between two rollers.
Rubber Injection Method: The injection method involves injecting the rubber compound into a pre-designed mold and filling the mold with high pressure to form the desired product shape.
2. Product Shape
Rubber Calendering: Suitable for producing flat or slightly curved rubber products.
Rubber injection molding method: applicable to the production of various shapes of rubber products.
3. Process control
Rubber calendering: process control mainly involves the distance between the two rollers and temperature adjustment.
Rubber injection molding method: process control mainly involves the design of the mold and the adjustment of injection process parameters.
4.Production efficiency
Rubber calendering: suitable for mass production, especially for relatively simple shape products.
Rubber injection molding method: suitable for small batch production and high requirements for the shape of the industry.
5. Product performance: injection molding method is slightly inferior to calendering method in terms of tensile strength and elasticity of products.
Advantages of rubber calendering
Productivity and Cost Advantages: Rubber calendering allows for mass production and increased productivity for large-scale manufacturing of rubber products. At the same time, rubber calendering is usually able to reduce production costs compared to some other rubber molding processes, especially for high-volume production.
Quality control and customization ability: Through good control and adjustment, rubber calendering can ensure that the dimensions and properties of rubber products have a high degree of consistency and improve product quality. Meanwhile, through different calendering roller designs and adjustment of process parameters, flexible control of rubber product shape and product customization can be realized to adapt to different demands.
Technical and environmental challenges faced
The pressure of energy consumption and environmental protection: With the improvement of environmental protection requirements, energy consumption, and environmental pollution in the rubber calendering production process has become a challenge, and it is necessary to find a more energy-saving and environmentally friendly production process.
Adaptability to new materials: With the continuous emergence of new rubber materials, rubber calendering technology needs to continuously adapt to the characteristics of new materials and improve its adaptability to various rubber materials.
Technical difficulty: the requirements of high precision and high consistency make rubber calendering technology face certain technical difficulties in process control and equipment manufacturing.
The complexity of the molding process: For some rubber products with complex shapes and high-performance requirements, rubber calendering may face the complexity and challenges of the molding process.
Conclusion
As an important rubber processing technology, rubber calendering can not only realize large-scale and high-efficiency production of rubber products and reduce the production cost, but also ensure the consistency of the products, improve the product quality, and flexibly adapt to different production demands through the precise control of the process. Therefore, rubber calendering technology is widely used in tire manufacturing, construction engineering, electronic products, medical devices, and other industries, playing a key and irreplaceable role in the manufacture of rubber products. For tailored calendering solutions, reach out to Crowns Machinery today.
