Introduction and Application of Pultrusion Process

 

Pultrusion is a molding method for producing FRP linear profiles. It is driven by a traction device to impregnate untwisted glass fiber roving and other continuous reinforcement materials with glue, preform them, and then solidify them through a heated molding mold to achieve continuous production of FRP products. Pultrusion technology was studied as early as 1948, and was first registered and patented in the United States in 1951. It really entered the field of structural materials in the early 1970s.

 

After that, pultrusion technology became a widely used process technology and gradually attracted the attention of all sectors of society. With the improvement of raw materials and equipment manufacturing level, many key technologies of pultrusion technology have made major breakthroughs and achieved rapid development. Most of the products of Shaanxi Taipuri Electrical Technology Co., Ltd. use this pultrusion molding process.

 

 

1. Advantages of Pultrusion Technology

 

(1) The physical and mechanical properties of composite products, especially the longitudinal specific strength and specific stiffness, are quite outstanding.

 

(2) The process is easy to realize automatic control and the product quality is stable.

 

(3) There is basically no scrap in the process, and the effective utilization rate of raw materials is high.

 

(4) The length of the product is only limited by the production space, and has nothing to do with the equipment capacity and process factors.

 

(5) With the gradual improvement of raw material varieties and specifications and the improvement of process level, almost any linear constant cross-section composite profile with complex cross-section can be formed by pultrusion process, and the ability to adapt to different uses and load requirements is gradually enhanced.

 

1. Application of Pultruded Products

 

Pultruded products are competing with traditional metal, wood, plastic, ceramic and other materials in the market with their unique advantages. They are widely used in sports, medicine, agriculture and various industrial fields. They are an excellent structural and decorative material.

 

(1) Application in the Electronic and Electrical Market

 

The electronic and electrical market is the earliest market for pultruded products. In recent years, new products have been continuously developed, and innovation is one of the development focuses. Typical pultruded products include: utility poles, electrical scaffolding, insulation boards, fuses, busbars, wire tubes, radio antenna poles, fiber optic cables, insulators, utility poles, cable trays, fuse tubes, and various other electrical components.

 

Pultrusion Section

 

 

2) Application in the Petrochemical Market

 

The petrochemical market is an important field for pultruded products. The pultrusion process is particularly used to manufacture standard profiles such as angle, I-shaped, and grooved, as well as pipes of various cross-sectional shapes. The thickness of the same product cross section is variable, and the length of the product is not limited. In chemical plants or factories with corrosive media, typical products include: pipe network support structures, structural profiles, grid floors, railings, overpasses and working platforms, sucker rods, downhole pressure pipelines, sliding guide wheels, ladders, stairs, mist eliminator blades, internal and external support structures of tank products, various pipes, tanks, towers, troughs and filter gratings for waste gas and wastewater treatment, offshore platforms and other products.

 

Walkways, Barriers, Stairs, and Guardrails Made of Pultruded Profiles

 

Handrail Made of Pultruded Profiles

 

Platforms and Railings Made of Pultruded Profiles FRP

 

(3) Application in the Construction and Machinery Manufacturing Market

 

Pultruded products are used to replace structural steel, alloy aluminum, high-quality wood and other materials in various construction and machinery manufacturing. They can be used to manufacture automobile bumpers, vehicle and machine tool drive shafts, body frames, leaf springs, transport storage tanks, packaging boxes, pads, luggage racks, etc. It is especially suitable for manufacturing floors, top beams, pillars, frames, etc. for aircraft, vehicles and ships. In these occasions, it not only provides sufficient strength but also reduces the weight of the structure, achieving the dual purpose of reducing energy consumption and increasing transportation capacity.

 

In addition, because its vibration resistance is better than that of traditional structural materials, it can also extend the service life of these moving components. Because it has high strength, good corrosion resistance and self-lubricating properties, it has become an excellent material for manufacturing agricultural machinery. Modern buildings and bridges also require structural materials with high strength, good vibration resistance and atmospheric corrosion resistance. Pultruded products meet these requirements and are ideal building materials.

 

Window Frames and Railings Made of Pultruded Profiles

 

(4) Application in the Decoration and Manufacturing Markets

 

In residential decoration and furniture manufacturing, operating tables, splints, crutches, medicine cabinets, instrument carts and various equipment brackets made of it are both strong and light. Pultruded products produced using dyed self-extinguishing resins are used to make residential fences, corridor railings, door and window frames, curtain frames, floor fan rods, various hand tool handles and furniture. They are strong, beautiful, fireproof and do not require painting. Horizontal bars, parallel bars, racket rods, fishing rods, etc. made of pultruded products are now excellent sports equipment. In addition, pultruded products can also be used to build large-scale amusement facilities, such as water parks.

 

Playground Stairs

 

(5) Application in the Military Market

 

Pultrusion products are also widely used in military products. In addition to being used as structural materials in various military aircraft, vehicles, and ships, they can also be used in composite armor of tanks and armored vehicles, gun parts, brackets, ammunition packaging boxes, camouflage equipment antennas, bulletproof plates, ship railings, etc. Due to its high strength, light weight, good vibration and corrosion resistance, it can reduce maintenance and improve the mobility of troops. Using it to make missile and rocket shells can reduce the weight of the projectile and increase the range.

 

III. Development Trend

 

1. Market Development Trend of Pultruded Products

 

With the continuous improvement of pultrusion process technology, pultruded products are becoming more and more diversified, from the initial size and structure of single tubes and rods to large size, complex cross-section, thick-walled products and other structural forms. Its key application areas are composite materials for bridges, composite materials for power transmission, structural components of civil engineering, high-rise building projects, composite materials for rail transit, etc.

 

Pultrusion Profile Tower

 

2. Development Trend of Pultrusion Process

 

Characteristics of pultrusion: First, the process is simple and efficient, suitable for large-scale production of high-performance fiber composite materials. The pultrusion line speed is known to reach more than 4 m/min, and multiple products can be produced at the same time, which further improves production efficiency. Second, pultrusion can best play the reinforcing role of fibers. In most composite manufacturing processes, fibers are discontinuous, which causes a great loss of fiber strength.

 

Even if continuous fibers are wound, the strength is lost to a certain extent due to the bending and overlapping of fibers. For example, in spiral winding, the tension of the fibers is generally only 75% to 85%. In pultrusion, the fibers are not only continuous but also fully straightened, which is an ideal form for exerting fiber strength. Third, the quality fluctuation is small. The pultrusion process has a high degree of automation, fewer processes, and a short time. The operating technology and environment have little effect on the quality of the product. Therefore, using the same raw materials, the quality stability of pultruded products is higher than that of other process products.

 

The pultrusion process is still under development. From the perspective of foreign development trends, the development focus is on the production of large-size, complex-section, and thick-walled products: new marine composite materials, power transmission, structural components of civil engineering, and high-rise building projects. At the same time, the pultrusion process has also evolved from a “black art” in the mold cavity to a more scientific experimental method, repeatedly verifying and studying the in-mold curing dynamics, and continuously optimizing quality and improving productivity with the help of various electronic equipment, resin injection, mold design, etc. With the development of advanced equipment, those processes that were previously considered unimaginable will continue to emerge.