What are the factors that affect the performance of glass fiber TEX?
In glass fiber production, Tex (Texas Expiration) is a key indicator of fiber or yarn fineness, defined as the weight in grams per 1000 meters of length. Therefore, a higher Tex value indicates a thicker fiber/yarn, while a lower Tex value indicates a finer fiber/yarn.
Factors affecting glass fiber Tex permeate the entire production process and can be mainly categorized into three types: drawing process parameters, spinneret design and condition, and the raw fiber and oiling agent system.
The following is a detailed breakdown:
I. Drawing Process Parameters (Core Control Link)
This is the most direct and dynamic adjustment of Tex.
1. Drawing Speed
· This is one of the most crucial factors. With a constant glass melt flow rate, a faster drawing speed results in a longer and finer glass fiber stretched per unit time, leading to a lower Tex value. Conversely, reducing the drawing speed increases the Tex value. Producing products with different Tex specifications is primarily achieved by adjusting the drawing speed.
2. Spinneret Temperature
* Spinneret temperature directly affects the viscosity and flowability of molten glass.
* Excessively high temperature: The viscosity of the molten glass decreases, flowability increases, and the flow rate from the nozzles increases. At the same drawing speed, the fibers become thicker, leading to an increase in the Tex value.
* Excessively low temperature: The viscosity of the molten glass increases, flowability decreases, the flow rate decreases, and the fibers become thinner, leading to a decrease in the Tex value. However, excessively low temperatures can cause a sharp increase in the fiber breakage rate.
II. Spinneret Design and State (Hardware Basics) The spinneret is the "mold" for glass fiber forming, and its state directly determines the initial diameter of the fibers.
1. Number and Arrangement of Nozzles
* A spinneret contains hundreds to thousands of nozzles. Each nozzle draws out a single filament. With a fixed drawing speed, the total number of nozzles on the spinneret directly determines the Tex value of the raw filament. The more nozzles, the greater the total fineness (Tex).
2. Exhaust Nozzle Orifice Diameter
* The inner diameter of the exhaust nozzle is fundamental to determining the monofilament diameter. A larger orifice results in more molten glass flowing out at the same drawing speed and viscosity, leading to a thicker monofilament and thus a higher overall TeX value.
3. Exhaust Plate Lifespan and Condition
* With increased usage time, the exhaust nozzle's orifice diameter may enlarge or deform due to high temperatures and molten glass corrosion. This causes uneven monofilament diameter and a slow drift in the overall TeX value. A severely aged exhaust plate will struggle to consistently produce products with the target TeX.
III. Raw Wire and Oiling System
1. Molten Glass Composition and Viscosity
* Different glass formulations (e.g., E-glass, C-glass, S-glass) have different viscosity-temperature characteristics. Even at the same temperature, the fluidity of molten glass with different formulations varies, affecting the outflow and final TeX. Maintaining the stability of the molten glass composition is crucial during production.
2. Glass Molten Material Level
The static pressure of the molten glass at the inlet of the sprue varies slightly with the liquid level in the furnace. A higher liquid level and greater static pressure cause more molten glass to flow out of the sprue, resulting in thicker fibers (increased TeX). Modern production lines have automatic liquid level control systems to maintain this parameter stable.
3. Sizing Agent (Oil)
The sizing agent itself has weight. Although its proportion is small, the uniformity and stability of its coating amount will slightly affect the final TeX measurement. More importantly, the composition and coating effect of the sizing agent will affect the fiber bundle structure, abrasion resistance, and resin compatibility. Poor bundle structure leading to monofilament scattering will introduce errors during measurement.
IV. Environmental and Operational Factors
1. Cooling Air System
The intensity, temperature, and uniformity of the cooling air distribution affect the cooling and solidification point of the fibers below the sprue. Unstable cooling will cause fluctuations in fiber tension, indirectly affecting the stability of the drawing process and the uniformity of TeX. 2. Tension Control of the Wire Drawing Machine
Stable tension is a prerequisite for ensuring a constant wire drawing speed. Tension fluctuations will cause slight changes in the actual wire drawing speed, thereby causing fluctuations in the TeX value.