Do you know the manufacturing process of fiberglass?
In our production, the main continuous glass fiber production processes are crucible drawing and tank furnace drawing.
Crucible Drawing Process
The crucible drawing process is a two-stage forming process. It involves heating the glass raw material until it melts, forming the molten liquid into spherical shapes, and then remelting these spherical shapes to draw them into fibers. However, this method has significant drawbacks, including high consumption, unstable product quality, and low yield. This is not only due to the inherently small production capacity and difficulty in process stability, but also closely related to the outdated control technology used. Therefore, currently, for products controlled by the crucible drawing process, the control technology has the most significant impact on product quality.
Generally, crucible control involves three main aspects: electro-melting control, perforator control, and spherical feeding control. In electro-melting control, constant current instruments are commonly used, but constant pressure control is also employed in some cases; both methods are acceptable. In percolator control, constant temperature control is commonly used in daily production, although some applications employ it. For ball-addition control, intermittent ball-addition is preferred. While these three methods are sufficient for everyday production, they still have drawbacks for producing high-quality glass fiber yarn. For example, the accuracy of percolator current and voltage control is difficult to maintain, percolator temperature fluctuates significantly, and the resulting yarn density varies considerably. Furthermore, some field instruments may not be well integrated with the production process, failing to specifically address the characteristics of the crucible method. Alternatively, the control methods may be prone to malfunctions and lack stability. These examples demonstrate the need for precise control, careful research, and continuous improvement in the quality of glass fiber products during production.
Key Aspects of Control Technology: Electrofusion Control
First, it is crucial to ensure a uniform and stable temperature of the liquid flowing into the percolator, and to guarantee the correct and reasonable crucible structure, electrode arrangement, and ball-addition position and method. Therefore, in electrofusion control, ensuring the stability of the control system is paramount. The electrofusion control system employs intelligent controllers, current transmitters, and voltage regulators. To reduce costs, a 4-digit effective digital instrument is used, while current transmitters with independent effective values are employed. In actual production, based on the results, this system, used for constant current control under relatively mature and reasonable process conditions, can control the liquid temperature flowing into the bath within ±2 degrees Celsius. Therefore, research has shown that its controllability is good, approaching that of the tank furnace wire drawing process.
Spindle Control
To ensure effective spindle control, the devices used are temperature- and pressure-controlled and relatively stable. To achieve the required output power, a higher-performance regulator is used, replacing the traditional thyristor trigger circuit. To ensure high temperature accuracy and low periodic oscillation amplitude of the spindle, a 5-digit high-precision temperature controller is used. The use of an independent, high-precision effective value transformer ensures that the electrical signal remains undistorted even under constant temperature control, and the system exhibits high steady-state performance.
Ball Addition Control
In current production, intermittent ball addition control in crucible wire drawing is one of the most significant factors affecting temperature during normal production. Periodic ball addition control disrupts the temperature equilibrium within the system, leading to repeated disruptions and readjustments, resulting in significant temperature fluctuations and difficulty in achieving precise temperature control. Continuous ball addition is another crucial aspect of improving system stability and addressing the problems associated with intermittent ball addition. Because traditional furnace liquid control methods are costly and impractical for daily production, a new method has been developed: ball addition is changed to continuous, non-uniform speed addition while using a probe to measure the liquid level. This overcomes the shortcomings of the original system. During wire drawing, the contact state between the probe and the liquid surface is adjusted to regulate the ball addition speed and reduce temperature fluctuations within the furnace. Alarm protection via the output meter ensures a safe and reliable ball addition process. Accurate and appropriate high and low speed adjustments ensure minimal liquid fluctuations. These modifications ensured that the system could maintain high-count yarn count fluctuations within a very small range even under constant pressure and constant current control.
Tank Furnace Drawing Process
The main raw material for the tank furnace drawing process is pyrophyllite. Pyrophyllite and other ingredients are heated to a molten state in the furnace to create a glass melt, which is then drawn into fibers. Glass fibers produced using this process account for over 90% of global production.
Tank Furnace Drawing Process Flow
The process flow for tank furnace drawing involves large pieces of raw material entering the factory, undergoing crushing, pulverizing, and screening to become qualified raw materials. These are then transported to a large silo, where they are weighed and mixed evenly before being transported to the kiln head silo. Finally, a screw feeder feeds the batch into the unit furnace for melting into molten glass. After the molten glass is melted and flows out of the unit melting furnace, it immediately enters the main passage (also called the clarification and homogenization or conditioning passage) for further clarification and homogenization. Then, it flows through the transition passage (also called the distribution passage) and the working passage (also called the forming passage) into the tank, and flows out through multiple rows of porous platinum stencils to become fibers. Finally, it is cooled by a cooler, coated by a monofilament oiler, and then drawn by a rotary drawing machine to produce untwisted roving bobbins. 2.3 Process Flow Diagram
Process Flow Equipment
Qualified Powder Preparation
Large raw materials entering the factory must first be crushed, pulverized, and screened into qualified powder. Main equipment: crusher, mechanical vibrating screen.
Batch Preparation
The batch production line consists of three main parts: a pneumatic conveying system, an electronic weighing system, and a pneumatic mixing and conveying system. Main equipment: pneumatic conveying system and batch weighing and mixing conveying system.
Glass Melting
The glass melting process involves selecting suitable raw materials and heating them at high temperatures to create molten glass. However, the molten glass must be homogeneous and stable. In production, glass melting is crucial, as it closely affects the yield, quality, cost, production rate, fuel consumption, and furnace lifespan. Main equipment includes: furnace and furnace equipment, electric heating system, combustion system, furnace cooling fan, pressure sensor, etc.
Fiber Forming
Fiber forming is the process of turning molten glass into glass fiber filaments. The molten glass flows through a perforated stencil and is then drawn into fibers. Main equipment includes: fiber forming chamber, glass fiber drawing machine, drying oven, stencil, automatic filament spool handling device, winding machine, packaging system, etc.
Sizing Agent Preparation
Sizing agents are prepared by adding water to epoxy emulsion, polyurethane emulsion, lubricants, antistatic agents, and various coupling agents. The preparation process requires jacketed steam heating, and deionized water is generally accepted for preparation. The prepared impregnating agent undergoes several processes before entering the circulation tank. The circulation tank's main function is circulation, allowing the impregnating agent to be recycled and reused, saving materials and protecting the environment. Main equipment: Impregnating agent preparation system.
Fiberglass Safety Protection
Enclosed Dust Sources: Primarily the enclosure of production machinery, including overall enclosure and local enclosure.
Dust Removal and Ventilation: First, an open space must be selected, and then exhaust and dust removal equipment must be installed in this space to remove dust.
Wet Operations: Wet operations force dust into a humid environment. Materials can be pre-wetted, or water can be sprayed in the work area. These methods help reduce dust.
Personal Protection: While external dust control is important, personal protection cannot be ignored. During operation, protective clothing and dust masks must be worn as required. If dust comes into contact with skin, rinse immediately with water. If dust gets into the eyes, provide emergency treatment and then seek immediate medical attention. And be careful not to inhale the dust.