Rubber Calendering In The 8 Kinds Of Common Defects And Repair Methods Revealed–Rubber calendering is a process whereby raw materials are calendered and extruded to form the required shapes and sizes. The calendering process ensures consistency of performance and quality of the rubber during production. Rubber calendering plays a vital role in the manufacturing industry. It is especially important in producing rubber products. Advanced manufacturing technology and strict quality control measures are the key to ensuring high-quality rubber products.
Rubber products are widely used in many industries such as automotive, electronics, construction, and medical. High quality rubber products have various properties, like abrasion resistance and high temperature resistance. These properties can be adapted to the needs of specific applications. It is used in critical areas, such as automotive braking systems, medical devices, and other rubber products. Its quality directly affects product safety performance. Ensuring the high quality of rubber products is crucial to both the production and use processes.
Table of Contents
Air bubbles and porosity
Bubbles and porosity are common defects in rubber products during calendering. They may negatively impact product performance and quality. The reasons for their formation include the following:
Quality of raw materials:Substandard raw materials or rubber with volatile components may release gas during processing. This may lead to the formation of bubbles and porosity.
Uneven mixing of raw materials: If the rubber is mixed unevenly during the mixing process, gases may remain in the rubber. These gases are not completely dispersed and form air bubbles.
Improper control of process parameters: If the calendering time, pressure, and temperature aren’t controlled properly, it may also lead to the formation of bubbles and air holes.
Bubble and porosity repair method:
Optimize the mixing process: Avoid gas generation by adjusting factors such as mixing time, temperature, and amount of additives. This will ensure uniformity and adequacy in the rubber mixing process.
Accurate control of process parameters: Accurately control the temperature, pressure, and time in the calendering process. This will ensure that there is no excess gas residue in the rubber processing.
Vacuum treatment: Vacuum-treating rubber before calendering can effectively remove excess gas and increase density. This reduces the generation of bubbles and air holes.
Use of degassing products: You can use specialized degassing agents to release gases from the rubber. This reduces the generation of air bubbles.
Uneven surfaces
Uneven rubber surfaces can lead to a variety of problems. These problems include poor appearance or reduced performance. Crowns Machinery describes less-than-flat fixes below. These methods include adjusting the calender roll spacing and optimizing the calendering temperature.
Problems, such as raw material quality or equipment wear and tear during production, can lead to uneven rubber product surfaces. This affects product appearance and performance.
Poor product appearance not only reduces the overall product aesthetics. It is also unfavourable to the brand image.
The uneven surface of some products, such as seals, will lead to a poor sealing effect. This affects the effectiveness of the product.
Uneven problem repair methods
Control the quality of raw materials:Using high-quality raw materials can greatly reduce uneven product surfaces.
Optimize the calendering temperature: Ensure that the appropriate calendering temperature promotes rubber fluidity. This, in turn, helps form a flat surface.
Adjust the distance between calendering rollers: Appropriate roller spacing can better control the rubber’s thickness. This helps achieve better smoothness and flatness.
uneven stretching
In the calendering process, rubber may be unevenly stretched. This may affect the performance and quality of the final product.
If the heating system does not provide uniform temperature to the rollers, the rubber will stretch unevenly as it passes through the different parts of the rollers during calendering.
The rollers have uneven pressure distribution. This causes each part of the rubber to receive different pressure during calendering. It also results in uneven stretching.
Repair method of uneven stretching problem
Adjust the temperature, pressure, and other parameters appropriately. This optimizes the stretching performance of the rubber.
Optimise the heating system to ensure consistent temperature distribution between the rollers.
You can optimize roller pressure uniformity with automatic pressure adjustment devices or by adjusting the hydraulic system.
foreign matter embedded
During the production process of rubber products, various impurities and other foreign matter are easily mixed into the rubber. This phenomenon is called foreign matter embedded, and may lead to the following problems:
Quality problems arise when foreign matter is embedded in rubber products. This affects the overall quality, including the product’s appearance and performance.
Safety issues: Foreign objects embedded in rubber products weaken the strength of rubber products. This can cause fractures and damage. In the rubber automotive industry and other high-security applications, it directly threatens user safety.
Prevention method: Strengthen the inspection of rubber raw materials. Strictly control the quality. Ensure no foreign matter is embedded. At the same time, strengthen staff training and equipment inspection. Improve awareness of foreign matter prevention and control.
Repair method: Remove the foreign matter. Then, use the rubber repair agent to fix the damaged area. At the same time, strengthen the quality control of production. This will ensure the timely detection of foreign matter.
too high or too low temperature
The rubber calendering process. If the temperature is too high or too low, it will affect the performance and productivity of rubber products.
Unsuitable temperatures will lead to uneven rubber distribution in the calendering process, causing bubbles and cracks. Temperature that is too high or too low will change the rubber’s molecular structure. It will affect the final product’s strength, elasticity, and other properties.
Impact on production efficiency: A temperature that is too high or too low will make it harder to control the production process. It will also increase the process’s instability and reduce efficiency.
Repair method:
Optimize the temperature control system: Optimize and adjust the temperature to a suitable range. Keep it stable through the regulation system.
Use insulation materials: Use insulation materials in important parts. This maintains temperature stability in the calendering process.
Use of cooling devices: Installing cooling devices in the equipment can lower the rubber temperature when it’s too high.
Roll surface wear
A calender roller will wear out over time due to friction. Once the roller surface is worn, the rubber pressure during calendering becomes uneven. This affects the performance and quality of rubber products. To ensure product quality, the worn roller will need frequent replacement. This will also reduce its service life.
Repair methods:
Use high-quality rollers: high-quality rollers naturally have good wear resistance and prolong service life.
Regular maintenance: Regularly clean the roller surface and lubricate the bearings and other components. This can effectively reduce roller wear.
Use of suitable coatings: Apply suitable protective coatings to the rollers’ surface to improve their wear resistance.
uneven thickness
Rubber products in the calendering process will be due to inconsistent roller spacing and other problems resulting in uneven thickness. This problem affects the following:
Uneven thickness will lead to performance differences in different parts of the rubber, such as elasticity and strength. This affects the reliability of the overall product.
Uneven rubber thickness can cause an uneven surface, bubbles, cracks, and other quality problems.
Repair method:
Adjust the roller spacing: According to the production demand, adjust the rollers to the appropriate spacing. This makes the rubber subjected to uniform force in the calendering process, ensuring a consistent thickness.
Adopt an online thickness detection system: You can measure the thickness of rubber products at any time using laser measurement and other technologies. If you find uneven thickness, adjust the relevant parameters promptly.
Regular inspection and maintenance of equipment: Ensure the consistency of roller spacing and the flatness of the roller surface. This ensures the normal operation of the equipment.
Under or over vulcanisation
Analyze the performance problems that may result from under or over vulcanization of rubber, like insufficient strength or excessive hardness. Provide remedies such as optimizing vulcanization time and temperature control.
In the vulcanization process, an incorrect degree of vulcanization will lead to under or over-vulcanization of rubber. This affects the stability of product performance in the following ways:
Insufficient vulcanization: Rubber products that are not vulcanized enough will have relatively poor performance in terms of strength and abrasion resistance.
Excessive vulcanization: Rubber products with excessive vulcanization become too hard and lose elasticity. They can break easily.
Repair method:
Adjust the dosage of vulcanizing agent: Increasing the dosage of the vulcanizing agent can promote the vulcanization reaction. Decreasing the dosage will reduce the vulcanization reaction. So, the degree of vulcanization of the product can be controlled by adjusting the dosage of vulcanizing agent appropriately.
Adjust the time and temperature of vulcanization: If the vulcanization is excessive, shorten the vulcanization time or lower the vulcanization temperature. Insufficient vulcanization can increase the vulcanization time or increase the vulcanization temperature.
Adoption of vulcanization monitoring system: The on-line monitoring system allows for adjusting vulcanization parameters as needed and for monitoring the vulcanisation process in real time.
Conclusion
Through the analysis of the above eight rubber calendering process in the common defects, as well as the corresponding repair methods, it is not difficult to find, from the quality of raw materials to the production process of real-time monitoring, as well as the maintenance of related equipment, are related to product quality, to reduce the occurrence of defects in the important links and measures. Therefore, strengthening quality control to increase the quality audit is the rubber calendering is to ensure that the product meets the standards of the key.
As a professional rubber calender manufacturer, Crowns Machinery has a wealth of knowledge about rubber calendering and can help you solve a variety of problems, welcome to contact us!
