Preparation And Tribological Behavior Of A Heavily Loaded 40Cr-PTFE Composite Bearings

For economical, ecological and even technical reasons for some years there has been a tendency to introduce self-lubricating materials for bearing applications. In this way external lubricants such as oil or grease can be excluded, and the design can be simplified. For example, the grease-lubricated sliding 45 carbon steel bearings were used in the clamping unit of plastic injection molding machines. The elements of plastics are always polluted by the lubricating grease. On the other hand, waste grease is also potentially environmental pollution, and it is also not able to meet the requirements of clear manufacturing. The commonly used solid lubricant embedded bearing and brass-plastics-steel DU bearing have difficulty in meeting the needs for bearings of plastic injection molding machines, such as heavy load-carrying capacity, high clamping frequency and long service life. Thus, the need for materials that are heavy load-carrying capacity and long service life is ever increasing. In the present work, 40Cr alloy steel was selected as the backing material, and PTFE composite was acted as a solid lubricant. The self-lubricating bearing was designed by an ANSYS software, and a solid lubricant embedded 40Cr-PTFE bearing was prepared. It was expected to be effectively strengthened leading to long service life.First, polytetrafluoroethylene (PTFE) composites filled with various contents of glass fibers (GF) and graphite were prepared by compression molding. The screening friction and wear tests were carried out in a reciprocating sliding tribotester. It is found that the optimal PTFE composite was a PTFE-25wt.%GF-5wt.%graphite amongst the composites.Second, PTFE composites were treated using different surface treatment methods. The adhesive strength tests were conducted by a standard experiment method. The maximum adhesive strength between PTFE and stainless steel was up to 5.63 MPa using the melting potassium acetate.Third, a solid lubricant embedded 40Cr-PTFE bearing and a bronze C86300-PTFE bearing were prepared. The comparatively tribological tests were performed in an oscillating sliding tribotester. The conditions were a contact mean pressure of 80 MPa, an oscillating frequency of 0.13 Hz and relative humidity of...