The internal mixer, abbreviated as "LiNa machine" and fully known as "sealed rubber mixer", was developed on the basis of the open mixer. After the invention of the open mill in 1820, the rubber industry underwent a fundamental transformation. However, due to the many shortcomings of the open mill, such as high labor intensity, low efficiency, and high dust, it seriously affected human health. Therefore, people began to consider whether this processing equipment could be covered with a cover, and gradually developed into an internal mixer. Because it works in the mixing room, it is called a closed type. Due to the open operation of the opening mixer, it is called an open rubber mixer. It is generally believed that the internal mixer was invented by Banbury in 1916. In fact, it was first designed by a commercial engineer (British) from West Germany based on the company's prototype machine. Due to its rapid development, large production capacity, and wide application, people have always believed that the Banbury internal mixer was the earliest to be introduced.
Since the emergence of internal mixers, a series of advantages have been demonstrated in the mixing process compared to open mixers, such as short mixing time, high production efficiency, easy operation, better overcoming dust flying, reducing loss of admixture, improving labor conditions, and reducing labor intensity. Due to its development largely based on experience, there was a belief in the early stages of development that the efficiency of molding was low and it could not be used for molding, but it has been denied by production practice. Therefore, the emergence of internal mixer is an important achievement of rubber mixing machinery, and it still remains a typical equipment in plastic and mixing, and is constantly developing and improving. According to foreign data statistics, 88% of rubber materials in the rubber industry are manufactured by internal mixers, and internal mixers are also widely used in the plastic and resin industries. Due to the continuous improvement of the metal powder industry, some can also be mixed using internal mixers.
Dongguan Zhenggong Electromechanical Equipment Technology Co., Ltd. was founded in 1988 in Dongguan, Guangdong. Its main products Small open mill, Small internal mixer, Small tablet press, small vulcanization machine, Small extruder, and various customized laboratory mixer rubber and plastic mechanical equipment. Established the Taiwan Joint Venture Business License in 2009, after more than 30 years of research and development and creation. It has been located in Houjie Town, Dongguan City, Chinese Mainland Province, mainland China.