With the continuous development of manufacturing processes, the weaving forms of packing glands have gradually diversified. Depending on the usage conditions and environment, different weaving forms directly affect the sealing performance and service life. The main weaving forms used in braided packing glands include: braided packing, layered braiding, through-core braiding, and sandwich braiding.
The weaving forms and characteristics of packing glands are as follows:
1. Braided Packing
Braided packing uses eight spindles running on two tracks to weave the packing. There is no core at the four corners and in the center. The cross-section of the woven product is square. Its characteristics are that the packing is loose, but it provides some compensation for shaft vibration and eccentricity. It is only used for small cross-section packings. However, with larger cross-sections, the packing surface will have a rough texture, loose structure, and poor density.
2. Layered Braided Packing
Layered braiding uses 8, 12, 16, 24, 36, 48, or 60 spindles woven on two tracks. The number of layers depends on the packing specifications, typically 1-4 layers. There is no central core. Layered packing provides good density and strong sealing, but because it is layered, the layers are prone to delamination due to the lack of fiber connections. Therefore, it is mostly used for static sealing or low-speed equipment.
3. Sandwich Braided Packing
Sandwich braiding uses rubber or metal as the core, with fibers on the outside, woven layer by layer. The number of layers depends on the needs. Similar to layered braiding, sandwich braiding offers good density, high strength, good bending performance, and good sealing. However, like layered structures, the surface layer is prone to detachment after wear. It is generally used in pumps and valves, and rarely in reciprocating equipment.
4. Through-the-core braiding
Through-the-core braiding uses 8, 12, 16, 24, 36, 48, or 60 spindles woven on three or four tracks. It has a square cross-section, a smooth surface, good elasticity and wear resistance, high strength, and good density. The contact surface with the shaft is larger and more uniform than that of braided packing, and the gaps between fibers are small, resulting in excellent sealing. Even after surface wear, the packing will not loosen, leading to a long service life. It is a relatively advanced braiding structure.
When selecting packing, the braiding method should be chosen according to the specific operating conditions of the equipment to ensure the packing achieves its intended sealing performance.
