Rubber O-rings are an essential component in rubber seal applications that are heavily used in many application industries. Linde Polymer will give you a comprehensive overview of the rubber O-ring manufacturing process. From the selection of raw materials to the inspection of final products, every step is very important to produce high-quality O-rings. Reading through this article from Linde Polymer hopefully gives you an idea of the complex processes involved in the production of these versatile seals.
Selection of raw materials for rubber O-rings
The first step in manufacturing rubber O-rings is to select appropriate raw materials according to needs. The selection of rubber compounds mainly depends on specific application requirements, such as high and low temperature resistance, chemical compatibility, hardness, and other performance requirements. Commonly used rubber materials for O-rings are nitrile rubber (NBR), silicone rubber (VMQ), fluororubber (FKM), ethylene propylene diene monomer (EPDM), etc. The process of selecting raw materials involves factors such as operating environment, fluid compatibility, and performance expectations.
Compound mix
Once the raw materials are identified, the next step is compounding, a process that involves mixing the rubber compound with various additives such as curing agents, accelerators, and fillers. The mixing process is usually carried out in an internal mixer. The goal is to obtain a homogeneous mixture, so that the additive is evenly dispersed throughout the rubber compound. Careful control of mixing time and temperature is required to ensure optimum curing performance and product consistency.
Preformed
After the compound is mixed, it comes to the preforming stage. Preforming requires making the rubber mixture into a specific shape and using existing molds to make the required O-ring shape. Typically, this is done using compression molding or injection molding techniques. Compression molding works by placing a compound into a mold cavity and applying heat and pressure to shape it. Injection molding, on the other hand, injects the compound under high pressure into a closed mold. Both methods produce preforms that can be used in the final forming process.
Forming
The molding process is the process of converting a preformed rubber compound into the final O-ring shape. It is achieved through a combination of heat and pressure. The preform is first placed in the mold cavity and heated to soften the rubber. The mold is then closed and pressure is applied to ensure that the rubber fills the entire cavity and forms the desired shape. At this time, it is necessary to precisely control conditions such as temperature, pressure and time, and finally achieve the specified curing and dimensional accuracy.
Post-cure
This step is to further enhance the physical properties of the rubber O-ring. Post-curing exposes molded O-rings to high temperatures for a specific period of time, a process that helps improve the product’s heat resistance, chemical resistance, and compression set. The post-cure process is an important step in the ability of the product to meet the required specifications and provide a reliable seal in the final application.
Deburring and inspection
After the post-curing process is complete, the O-rings are deburred to remove excess rubber or burrs that may have formed during the molding process. Deburring can be done manually or using automated equipment, depending on production volume. After deburring, the product is thoroughly inspected for defects or blemishes. Inspections include dimensional accuracy, surface finish and overall quality. Any problematic products will be judged as non-conforming products and will not leave the factory, and qualified O-rings will enter the final stage.
Packaging and storage
The final step is packaging and storage, carefully packaged to prevent damage during shipping and storage. Typically stored in a controlled environment to maintain their physical properties and extend shelf life, appropriate labeling and data ensure product traceability and easy identification when required.
