Rubber sealing strips are a very common product in our daily lives; many of the seals used on doors and windows in homes are rubber seals. Based on their structure, rubber sealing strips can be divided into two types: single‑extrusion seals and composite seals. Different types of seals require distinct production equipment and processes. For example, single‑extrusion seals are manufactured using an extrusion line that employs a rubber extruder to form the product, followed by three-stage hot‑air curing ovens for in‑line curing, and finally water cooling to produce the finished item. The production process for single‑extrusion rubber seals is relatively simple, with straightforward equipment operation. In contrast, the three‑layer composite seals used in automobiles necessitate more auxiliary equipment. During extrusion, two rubber extruders are employed to shape the material; their output is fed through a three‑layer die head, where the rubber from each extruder is laminated together to create the desired composite structure. After curing, the product must undergo further processing—such as punching, web cutting, and final shaping—before it is ready for use. Thus, the equipment configurations of different sealing‑strip production lines vary, and it is essential to select the appropriate setup based on the specific product type.

1. Operating Principle

Extrusion molding is a manufacturing process in which a plasticizable compound is continuously forced through a die under specific conditions, thereby forming a product with a defined cross-sectional shape.

As the rubber compound advances along the screw, mechanical and thermal effects cause changes in its viscosity and plasticity, transforming it into a viscous fluid. Based on the material’s behavior during extrusion, the working section of the screw is typically divided into three distinct zones—feeding, compression, and metering—each serving a specific function.

2. Cold-feed extrusion

Advantages: It saves on hot‑melt processing equipment, facilitates mechanization and automation, and, thanks to the extruder’s enhanced screw shear and plasticizing action, ensures uniform temperature and plasticity of the compound. It also improves the quality of extruded products, enhances surface finish, and produces semi‑finished extrudates with more stable and consistent dimensions. Furthermore, cold‑feed extrusion is less sensitive to pressure fluctuations and offers greater operational flexibility, while requiring lower capital and operating costs.

3. Equipment Features

Suitable for extruding rubber compounds (EPDM, natural rubber, nitrile rubber, butyl rubber, and reclaimed rubber), it is used in the production of composite sealing strips for architectural doors and windows, single‑extruded sealing strips for automobiles, as well as a wide range of dense and foamed rubber products—such as strip‑shaped, bar‑shaped, tubular, and sheet‑like items—for applications in construction, electrical appliances, machinery, water conservancy, and other industries.

Cold-feed rubber sealing strip extruder: This is a type of equipment that uses cold rubber in the production process, typically employing forced cold feeding. Cold-feed rubber extruders are characterized by high production efficiency and stable operation. Extruders are commonly used to manufacture products such as sealing strips and rubber hoses, which can be produced via extrusion. An extruder is a rubber‑processing machine designed for extruding tire treads, inner tubes, rubber hoses, and various rubber profiles.

Hebei Shuangda Rubber & Plastics Machinery Co., Ltd. is a modern enterprise integrating research and development, manufacturing, and sales of complete sets of extrusion equipment for rubber, silicone, and plastics. The company’s main products include rubber extruders, rubber hose extrusion lines, three‑layer composite sealing strip extrusion lines, silicone sealing strip production lines, plastic sealing strip production lines, plastic profile production lines, plastic pipe production lines, elastomer extruders, and other extrusion equipment, as well as production machinery for engineering seals, automotive seals, wire and cable applications, air‑conditioning hoses, braided hoses, automotive hoses, waterstop strips, and related products.