Time：2019-09-25| Author：Admin
Casting
Cast nylon 6 has high strength, abrasion resistance, scratch resistance and resilience. Casting reactions are mostly carried out at atmospheric pressure or at very low pressures, so cast nylons have a distinct advantage over extruded or molded nylon. Compared with extruded nylon, cast nylon has higher crystallinity and molecular weight, better dimensional stability, easy machinability, higher modulus and heat distortion temperature.
Because the size and shape of the cast nylon is not limited, it has greater flexibility. Low-cost tools can be used to produce cast nylon with a simple shape and a short production cycle; complex parts need to be produced in complex tools. Try not to use a high-priced casting machine in the social club. The lactam monomer is subjected to an anionic polymerization in a mold and finally converted into a polymer. Therefore, the reaction of the anhydrous acid catalyzed process is poor, and the conversion efficiency is low. Therefore, many catalytic reactions are selected to obtain better results. Co-catalysts have been developed since the 1950s, and more efficient production machinery was developed in the late 1960s to accelerate the commercialization of cast nylon.
Rotational molding
Rotational molding, also known as rotational molding, is a process for the manufacture of hollow seamless products of various sizes and shapes. Traditionally, it has been mainly used in thermoplastic materials. In recent years, rotomolding of thermosetting materials such as cross-linked polyethylene has also developed rapidly. Since rotomolding does not require high injection pressures, higher shear rates or precise compound gauges. Therefore, the molding and the machine are relatively inexpensive and have a long service life. The main advantages are: the performance / price of the machine is relatively high; the molding of complex parts does not require post-assembly; multiple products and multiple colors can be molded at the same time; the cost of the mold is low; the color and material are easy to change; the loss of scrap is small.
The basic process is simple. The powdered or liquid polymer is placed in a mold, heated while rotating around two vertical axes, and then cooled. At the beginning of the heating phase, if a powdery material is used, the surface of the mold is formed into a porous layer and then gradually melted as the cycle progresses to form a uniform layer of uniform thickness. If a liquid material is used, it is first flowed and coated. The surface of the mold stops flowing completely when the gel point is reached. The mold is then transferred to the cooling station, cooled by forced air or water spray, and then placed in the work area where the mold is opened, the finished part is removed, and the next cycle is performed.
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