Flame retardant and heat insulation fabric for fire suits serves as the core base material to resist flash fire, high-temperature thermal radiation and splashes of molten metal in automotive manufacturing workshops. Unlike ordinary fabrics treated with secondary flame-retardant finishing, this material adopts inherently flame-retardant fibers as the substrate and adopts a multi-layer composite structure integrating flame resistance, heat insulation, thermal radiation resistance, abrasion resistance and anti-static properties. Instead of a single textile sheet, the fabric is a composite system made of an outer protective textile, barrier film and thermal insulation liner. Fiber selection, weaving techniques and surface modification treatments for each layer directly determine the suit’s ability to withstand high temperatures and protect operators.

　　The fabric substrate is a blend of meta-aramid and a small amount of para-aramid fibers. It is an inherently flame-retardant material whose flame resistance is built into the polymer molecular structure, rather than relying on externally attached flame retardants. When exposed to flame and high temperature, the fibers will not melt and drip, but gradually carbonize to form a dense char layer that isolates heat and oxygen and stops the continuous combustion chain reaction. Meta-aramid delivers basic flame retardancy and softness, while para-aramid improves tensile, tear and abrasion strength to resist physical wear caused by metal burrs and welding slag in workshops. Raw fiber materials are purified and screened to remove impurities and low-melting components and avoid local melting under high heat. After repeated laundering in factories, the fabric’s flame-retardant performance will not degrade rapidly, matching the frequent cleaning cycles in automotive workshops.

　　The fabric adopts a three-layer composite structure, each layer undertaking separate functions. The outermost layer is the protective face layer woven in twill weave. Dense yarn interweaving improves splash and abrasion resistance. During weaving, warp and weft density is controlled to balance structural strength with breathable and moisture-permeable channels, preventing excessive fabric density that traps internal heat. The outer surface undergoes low-surface-energy modification to reduce wettability by molten metal droplets, so welding slag slides off quickly after contact and lowers the risk of burning adhesion. The middle layer is a microporous barrier film. It blocks penetration of liquid high-temperature substances and combustible particles while allowing sweat vapor from human skin to escape outward, easing heat stress during long wear and preventing stuffiness inside the garment. The inner layer is fluffy thermal insulation felt made of aramid spunlace nonwoven fabric. A large volume of static air is trapped inside the felt. Since air has low thermal conductivity, the air layer blocks heat conduction and forms the core source of thermal insulation for the fabric. The three-dimensional pore structure of fluffy nonwoven fabric reflects and attenuates thermal radiation energy repeatedly and further reduces heat flux penetrating toward the wearer’s skin.

　　Fabric weaving and post-finishing are critical to balance flame retardancy, heat insulation and wearing comfort. In the weaving stage, controlled high-tension looms are used to control internal fabric stress and prevent heavy shrinkage and deformation after heating or laundering. Shrinkage would tighten finished garments and squeeze internal insulation pores and weaken heat insulation. After weaving, grey fabric goes through singeing, desizing and pre-shrinking in sequence. Singeing removes loose surface staple fibers and reduces lint adsorption of paint mist, dust and metal debris. Desizing removes weaving sizing agents and ensures uniform penetration of functional chemicals. Hydrothermal pre-shrinking eliminates residual fabric stress. Functional padding is applied after pretreatment to implant anti-static components simultaneously and prevent static charge buildup that could ignite paint solvent vapor. The liquid pickup rate during padding is strictly controlled. Excess chemicals clog pores and reduce air permeability and thermal insulation; insufficient dosing fails to deliver required anti-static and anti-splash modification. Low-temperature curing after padding firmly locks functional components onto fiber surfaces and improves laundering durability.

　　Fabric performance inspection runs through the whole production process, including raw material sampling, grey fabric inspection and full-scale testing of finished fabric. Key test items cover vertical flame test, thermal protective performance test, molten metal splash test, tear strength, surface resistance and wash stability. The vertical flame test verifies self-extinguishing performance: qualified fabric stops burning rapidly once the flame source is removed, with no afterflame, afterglow and no molten dripping. The thermal protective performance test evaluates overall heat insulation, simulating flash fire conditions and measuring the time required for heat to penetrate the fabric and reach simulated skin. Higher thermal protection index means stronger resistance against short-duration high temperature. The molten metal splash test simulates workshop welding slag impact and observes droplet sliding behavior on fabric to assess anti-adhesion burning performance. The fabric also undergoes repeated wash aging tests. Flame retardancy, heat insulation and anti-static indicators are retested after multiple washing cycles. Fabric batches with fast performance degradation are screened out and forbidden for garment cutting.

　　Control of fabric limitations and scenario adaptation are equally important. Simply thickening fabric improves heat insulation, but greatly increases weight, reduces limb mobility and easily causes fatigue and heat stress during long-time wear. Too thin fabric, on the other hand, has insufficient heat insulation and cannot resist strong thermal radiation. Therefore, the fabric supports zoned cutting. Rolls of fabric can be cut into panels for different body regions. Full three-layer composite fabric is used for high-risk zones including chest, shoulders and upper arms. Lightweight double-layer composite fabric is adopted for armpits, waist sides and joints. It retains basic flame retardancy and heat insulation while reducing load and preserving flexibility during assembly and welding operations.

　　Fabric storage and maintenance also affect service life. Finished fabric rolls should be stored away from light and moisture, avoiding long-term strong light exposure and oil contamination that may age and invalidate surface modified coatings. During garment cutting, cut edges must be sealed to prevent yarn fraying, which would damage fabric pore structure and weaken thermal insulation. On-site in automotive workshops, once fabric suffers ablation, tearing or coating damage with exposed inner insulation felt, its flame retardant and heat insulation capacity will drop sharply. Such fabric must be retired immediately and cannot continue to be used.

　　In summary, flame-retardant heat-insulation protective fabric integrates flame resistance, heat insulation and splash resistance with breathability, relying on inherently flame-retardant aramid fibers and multi-layer composite construction. Its safety performance is guaranteed by fiber material, woven structure, functional modification and performance testing. This fabric is specially developed for high-temperature spark hazards in automotive manufacturing workshops. It blocks flame and thermal radiation while preserving wearing comfort, lowers burn risks for operators and provides stable and reliable thermal protection for frontline workers in automobile production.