Automobile blow mold companies are usually very cautious in the design and manufacturing of fuel tanks, and most companies will first adopt rapid molds for experimentation. The fuel tank can be said to be the power source of a car and is crucial for its manufacturing.

-Raw Materials

Most modern mold manufacturers use HDPE blow molding technology to manufacture automotive fuel tanks. Compared with traditional iron fuel tanks, HDPE fuel tanks have significant advantages, such as being lightweight, strong chemical resistance, simple molding, durability, high safety, and simple processing technology. Automotive fuel tanks require materials with good airtightness to prevent fuel penetration. At present, most manufacturers use co-extrusion or chemical treatment on the surface of formed parts to improve the barrier properties of HDPE as a fuel tank.

The so-called layered blending barrier modification refers to the dispersion and layered distribution of barrier resins that can act as barriers, such as nylon or ethylene vinyl alcohol copolymers, in continuous camera body resins. The barrier layer and substrate can form a multi-layer structure, making the penetration path of solvent molecules in the container more tortuous, thereby increasing the length of the path and enhancing the barrier performance. The production technology of this fuel tank is advanced, and automotive mold companies such as Citroen, Volkswagen, Renault, Ford, General Motors, and Chrysler have widely used this technology to produce fuel tanks.

The purpose of chemical treatment on the surface by mold companies is to change the chemical properties of the product surface, such as improving the polarity and cohesive energy density of plastic products, to achieve the goal of improving barrier performance. The main methods include fluorination, sulfonation, and plasma treatment. The so-called fluorination method is the use of highly reactive fluorine gas as a fluorination reagent to modify HDPE materials, commonly known as direct fluorination. The main principle is that fluorine atoms replace the hydrogen on the polymer chain, and a chemical reaction occurs on the surface of the container, thereby improving the polarity, molecular structure, and surface tension of the product, and improving the airtightness and barrier of HDPE fuel tanks. But when using this method, the mold company needs to be aware of the drawbacks of fluorination treatment, such as its ability to only improve the barrier to non-polar solvents, and its barrier to polar solvents is poor. The basic principles and production equipment of sulfonation and chlorosulfonation methods are consistent with those of fluorination methods and have been widely applied, gradually developing and maturing.

-Workmanship

Hollow blow molding is the process of extruding or injecting molten plastic into a preform, which is then directly or indirectly placed in a blow molding mold. Compressed air is introduced to blow and expand the preform, making it tightly adhere to the mold cavity. Finally, through cooling and shaping, a plastic hollow product with the same shape as the mold cavity is obtained. Hollow blow molding has unique advantages for forming hollow products with complex structures or large volumes.

For example, when blow molding companies blow complex-shaped plastic fuel tanks, various parts of the blank are prone to uneven deformation during the blowing process, resulting in uneven wall thickness of the parts. Blow molding mold companies need to design complex-shaped molds and mouth molds based on the deformation of various parts of the product, to improve the wall thickness uniformity of the extrusion blow molding oil tank. Blow molding mold companies can also monitor product quality in real-time by controlling the axial or radial thickness of the damaged wall, and make timely adjustments to the product.

Because low-density polyethylene (LDPE) is a highly crystalline material, it undergoes significant deformation and contraction upon cooling, which can easily lead to stress concentration and uneven wall thickness, affecting its performance and aesthetics. To solve this problem, blow molding companies can combine external cooling with internal cooling, increase the temperature of the cooling water appropriately, to ensure that it can fully crystallize at the same time, ensure uniform shrinkage, and

provide sufficient pressure to ensure shape stability and consistency.