Study on the Accuracy of Injection Molded Plastic Gear with the Assistance of Supercritical Fluid and a Pressurized Mold

• Published in: Polymer-plastics technology and engineering Vol. 46; no. 9; pp. 815 - 820
• Main Authors: Yoon, Jae D., Cha, Sung W., Chong, Tae H., Ha, Young W.
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Taylor & Francis Group 03.09.2007; Taylor & Francis
• Subjects: Application fields; Applied sciences; Cellular; Exact sciences and technology; Forms of application and semi-finished materials; Injection molded plastic gear; Polymer industry, paints, wood; Pressurized mold; Supercritical fluid; Technology of polymers; Viscosity; Viscosity; Durability; Supercritical fluid; Shrinkage; Experimental study; Cellular plastic; Property processing relationship; Gear; Acetal polymer; Pressure effect; Foaming process; Pressurized mold; Injection molding; Supercritical solvent; Injection molded plastic gear; Plastics; Application
• ISSN: 0360-2559; 1525-6111
• DOI: 10.1080/03602550701278046

Plastic gears are lighter and less noisy compared to steel gears, and they can be easily shaped into diverse forms by the injection molding process. For this reason, plastic gears are widely used in industry. An extensive amount of research has been conducted on gear materials and methods of shaping plastic gears for durability and for broader applications. In this article, the focus is on producing a plastic gear shaping method incorporating the injection molding process. The most important factor influencing the durability of a plastic gear is its accuracy. Unlike steel gears, the dimensions of plastic gears are subject to considerable change during formation, and this is due to certain conditions during the injection molding process and to the mold structure. The main causes of size variability here are the high viscosity of plastic and the shrinkage ratio of the resin. In our study, a supercritical fluid was used to reduce the viscosity of the plastic, and a pressurized mold was used to control the shrinkage ratio of the resin. Thus, production of an improved, more highly accurate plastic gear was achieved.