Factors related to sealing components (auxiliary materials):
① Inappropriate material: The hardness of the sealing ring is crucial for deformation. If the hardness is too low (such as pure aluminum), it may undergo excessive deformation; if the hardness is too high (such as silicon-aluminum alloy), it will not deform enough. Both cases fail to effectively fill the gaps under internal pressure, resulting in slurry leakage. Aluminum-magnesium alloy (such as 5052) has moderate hardness and shows better performance.
② Size or shape deviation: If the dimensions (such as diameter, thickness, angle) or flatness of the sealing components do not meet the requirements, it can lead to poor fitting with adjacent parts and inadequate encapsulation, failing to create an effective seal.
Component pressure and back-pressure factors: ① Insufficient component pressure: Especially for components that use a self-sealing structure, initial pressure that is too low can lead to sealing failure. For example, when self-sealing components are producing porous fine filaments, the pressure generally needs to be maintained above 15-19 MPa to ensure effective self-sealing.
② Excessive back-pressure (resistance) on the spinner plate: When the back-pressure generated by the spinner plate exceeds 60% of the internal component pressure, it creates an abnormal pressure differential in the sealing structure, which can easily lead to slurry leakage.
③ Pressure fluctuations and super-high pressure: Excessive fluctuations in component pressure during production, or final pressure exceeding the design limit (e.g., 23.0 MPa), risks damaging the seals and pipes.
Equipment and operational factors: ① Poor hydraulic press condition: If the hydraulic press is not level, it can lead to uneven punching pressure or insufficient hydraulic pressure, preventing effective locking of the sealing components.
② Damage during assembly and disassembly: Improper handling during assembly or cleaning (especially thermal decomposition), such as using tools that scratch, impact damage, or dropping from height, may cause deformation or scratches on key components like the distribution plate and sand cup, damaging the flatness of sealing surfaces.
③ Frequent start-stop operations or long idle times: This can cause dramatic changes in internal temperature and pressure, affecting the stability of the seal.
④ Significant differences in melt pressure at different spinning positions: For DIO components, if the melt pressure on the left and right sides is designed to be different but deviates excessively, it may also cause an imbalance in sealing.
Additional Challenges of Special Fiber Varieties
① Island Silk/Composite Filament: Their component structures are complex, with a significantly higher number of sealing surfaces than conventional components (e.g., 8-9 sealing surfaces). This imposes very high requirements on the dimensional accuracy, deformation, and surface condition of all parts. Any slight damage or deformation may lead to slurry leakage.
②Full Matte/Semi-Matte/Modified Fibers: Due to the high content of TiO₂ or other additives (like antibacterial agents), the melt properties change, which can lead to a rapid increase in component pressure, posing challenges to seal durability.
Solutions and Improvements
In response to the above reasons, we have compiled the following solutions:
Optimize Sealing Component Selection and Management
① Strict Material Selection: Choose materials with moderate hardness and stable deformation characteristics, such as aluminum-magnesium alloy 5052 for sealing rings. ② Strengthen Dimension Inspection: Establish strict internal control standards for key dimensions of sealing components (such as diameter, angle, flatness) and implement comprehensive inspections to ensure perfect fitting with parts.
Optimize and Stabilize Process Parameters
① Set Reasonable Initial Component Pressure: Based on the sealing form of the component (mechanical seal/self-sealing) and product specifications (especially fine and porous filaments), set and stabilize the initial pressure. For example, self-sealing porous fine POY is recommended at 15-19 MPa. ② Optimize Spinner Plate Design: Select appropriate spinner plate hole diameter and length-to-diameter ratio to avoid excessive back-pressure. For special varieties, a central-ring spinning component can replace the eye-shaped design to improve melt distribution and reduce slurry leakage.
Standardize and Refine Operational Procedures
① Improve Assembly and Disassembly Operations:
Assembly: Implement "5S" management in the environment, clean components with alcohol, and blow out filter materials with clean compressed air.
Disassembly (especially for island components): Use soft tools made of copper (brass or bronze); lay silicone mats on the workbench and transport vehicle to prevent component collisions; control hydraulic pressure during disassembly to avoid rough impacts. ② Enhance Cleaning Process Protection: Control water pressure during high-pressure cleaning of components or add protective nets; secure easily loosened parts like needle plates during ultrasonic cleaning. ③ Standardize Machine Operation: After removing old components, thoroughly clean the lower edges of the spinner box component and any residues on the installation tools to ensure the cleanliness of the new component installation surface.
Enhance Equipment Maintenance and Component Management ① Regular Inspection and Grinding: Check the flatness of key planar components like distribution plates and grind those exceeding parallelism standards for repair. ② Improve Component Design: Consider increasing the thickness of the distribution plate to improve resistance to deformation, or add copper gaskets between the spinner plate and housing to compensate for minute deformations and prevent slurry leakage.
Implementation Cycle Replacement and Archive Management
Establish usage archives for spinner plates, sealing components, and others, mandating regular replacements to avoid the accumulation of defects due to overdue usage.
Special Control for Specific Components (e.g., Island Silk)
Implement Comprehensive “Protective” Operations: From disassembly, cleaning, and transportation to assembly, each stage should focus on preventing physical damage to components.
Explore Structural Improvements: For example, by improving the shape and size of the thermal insulation pad, potential minor seepage can be contained within specific internal areas, avoiding impacts on normal production and thus extending the effective production cycle.
Summary
Slurry leakage in spinning components is an issue influenced by multiple factors (materials, processes, equipment, and operations). The fundamental solution lies in selecting qualified sealing materials and components, setting and stabilizing scientific working pressures for components, and executing detailed, standardized operation and maintenance processes throughout the entire lifecycle (from disassembly, cleaning, assembly to installation) to minimize damage and contamination of the components.
