Operational Procedures for Starting Up Polyester Melt Direct Spinning
In the field of polyester fiber production, the melt direct spinning process has become one of the mainstream production modes due to its advantages of a short process, low energy consumption, and stable product quality. The startup phase, as the “first checkpoint” of production, directly determines the stability of the subsequent yarn quality and production efficiency. This article outlines the standardized startup process for polyester melt direct spinning, based on frontline practical experience, to assist process personnel in accurately controlling each key point.
一、Preparation Before Startup: Details Determine Success or Failure
Comprehensive inspection and preparation before startup are crucial to avoiding startup failures and must cover three dimensions: equipment, materials, and personnel.
Equipment System Inspection Organize technical personnel to conduct a full-process inspection of core equipment, including melt delivery pipelines, spinning boxes, metering pumps, spinnerets, and winding machines. Confirm that the melt pipeline heating system is normal, with no blockages or leaks; the temperature sensors and insulation of the spinning box are intact; the metering pump operates smoothly, with no corrosion on parts in contact with the melt; the spinneret must be thoroughly cleaned to ensure that the micropores are clear of impurities; the guide rollers, tension sensors, and take-up devices of the winding machine are properly adjusted, and the operating parameters meet process requirements.
At the same time, check the cooling air system to ensure that the cooling air speed and direction are uniform and stable, and that the distance between the air nozzle and spinneret plate matches the process set values precisely.
2. Preparation of Materials and Utilities Confirm that the properties of the polyester melt, such as viscosity and the content of terminal carboxyl groups, meet the requirements for the production grade, and ensure that the liquid level in the melt delivery tank is within a safe range. In terms of utilities, pre-adjust the pressure and temperature of steam, circulating water, and compressed air to ensure a stable power supply without fluctuations, preventing interruptions in startup due to abnormal utility parameters.
3. Personnel and Safety Preparation Clarify the division of labor within the startup team, appointing responsible persons for spinning, winding, equipment, and quality to ensure that each link has dedicated personnel. Conduct safety briefings for operators, emphasizing safety operating procedures for high-temperature melts and high-speed equipment, and check that personal protective equipment (such as high-temperature gloves and face shields) is fully equipped.
二、 Core Startup Process: Step-by-Step Operation, Precise Temperature Control
The startup process for polyester melt direct spinning must follow the sequence of "Heating—Melt Delivery—Metering and Spinning—Cooling and Shaping—Winding and Take-Up," with strict control of process parameters at each step.
System Temperature Rise and Preheating Gradually raise the temperature of the melt pipeline and spinning box according to the preset temperature curve. Rapid heating that causes uneven thermal expansion of the equipment is strictly prohibited. During the heating process, personnel can be assigned to vent the high
Melt Delivery and Pressurization Start the melt delivery pump and slowly deliver the polyester melt into the pipeline while monitoring the pressure changes within the pipeline to avoid a sudden pressure rise that could cause back pressure and stall the polyester section.
Metering and Spinning Start the metering pump to quantitatively feed the melt into the spinneret plate at the preset rotation speed. Initially, the metering pump speed can be slightly reduced; once the melt is stable, gradually increase it to the process set speed. Observe the spinneret condition; under normal circumstances, the melt should be extruded from the spinneret plate’s micropores in a continuous and uniform thin stream, without hairiness, fusion, or breaks. If abnormalities occur, promptly check for blockages in the spinneret plate or temperature fluctuations.
Cooling and Shaping, and Oiling After the melt is extruded as a fine stream, it quickly cools and solidifies through the cooling air, forming the initial fibers. Strictly control the speed and temperature of the cooling air; excessive wind speeds may cause yarn shaking, while insufficient cooling adversely affects fiber strength. After cooling, the initial fibers enter the oiling device, where oil is evenly applied through nozzles to reduce friction between fibers and prevent static electricity during subsequent winding. The oiling rate must be controlled within the process requirements; excessive oiling leads to waste, while insufficient oiling affects fiber processing performance (bubbles in the oil should be discharged in advance if necessary).
Winding and Initial Quality Inspection Adjust the process parameters of the winding machine to wind the oiled yarn onto the take-up tube. During the initial winding stage, closely monitor the arrangement of yarns on the take-up tube to ensure neat alignment without overlaps or hard edges. After winding for a certain period, take samples for initial quality inspection, checking indicators such as linear density, breaking strength, and elongation at break. If the indicators meet the requirements, proceed to the stable production phase; if there are anomalies, promptly adjust the process parameters.
三、Common Issues and Solutions After Startup
During the startup process, common issues such as hairiness, fusion, breaks, and non-compliance with fiber specifications may occur, requiring targeted solutions:
Hairiness and Fusion: These are often caused by uneven cooling air speed or fluctuations in spinneret plate temperature. Adjust the cooling air parameters, check the stability of the spinning box temperature, and clean the spinneret plate if necessary.
High Break Rate: This may be due to excessive impurities in the melt, unstable metering pump speed, or insufficient oiling. Investigate the quality of the melt, calibrate the metering pump speed, and adjust the oiling rate.
Large Linear Density Deviation: This is mainly caused by deviations in the metering pump speed or fluctuations in melt pressure. It is necessary to recalibrate the metering pump and stabilize the melt delivery pressure.
四、 Conclusion
The polyester melt direct spinning startup process is a systematic operation that requires attention to equipment status, process parameters, and personnel cooperation. Only by strictly following standardized procedures and precisely controlling every detail can successful startup be achieved, ensuring subsequent production stability and product quality.
