FRICTION AND WEAR OF POLYPROPYLENE - AISI P20 MOLD STEEL TRIBOSYSTEM

摘要

Polymers have replaced metals and ceramics for a number of applications since the beginning of the 20th century. Today, pieces made with polymers are used as sliding pairs against metals or other materials. Their tribological behavior denoted by good wear resistance and low friction made them appropriate for a wide variety of applications including automotive parts, aircraft components, food processing industry, among others. In polymer tribology, most of the studies are focused on engineering polymers such polyamide, polyetherimide, polyetheretherketone, polyimide and polytetraflourethylene. However, there are "very simple" tribosystems where the commodities are involved. These systems have not been intensely studied so far but day after day there are problems in the applications and processing methods such as injection molding of deep products, filaments' extrusion, and thermoforming, among others. In injection molding, it is easy to find problems in ejection systems, such as impossibility to extract the product or the fact that sometimes the product remains in the opposite side of the expulsion system, especially in mirror surfaces' molds. In extrusion, the product is adhered in the calibration or cooling system. In blowing extrusion, the film is adhered in transport roll. It causes the shut-down of the machine increasing the amount of waste. In thermoforming, the situation is similar to injection molding. The conditions used in this study do not correspond to any process or sliding system. Nevertheless, the experimental setup allows for a close look to "unknown" polymer - metal tribosystem. These results must not be extrapolated to any specific processing conditions.