Project Details
Projekt
Solid Lubrication of Worm Gears based on PTFE
Applicants
Dr. Michaela Gedan-Smolka; Professor Dr. Michael Kopnarski; Professor Dr.-Ing. Bernd Sauer
Subject Area
Engineering Design, Machine Elements, Product Development
Term
since 2018
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 407535491
Worm gears provide thru their compact design and the high gear ratio for many positioning subjects for example in food technology and medicine technology a good solution. For safety requirements worm gears of steel worm and plastic worm wheel are not considerable. For particular safety requirements worm gear part of metal are necessary.In medicine or food technology frequently fluid-free gears are requested. Should the gears serve in very low or even high temperatures fluid lubrication is not the choice. The aim to realize a fluid-free worm gear is subject of the project, based on knowledge from PTFE as solid lubricant. PTFE can be used in a wide temperature range (-200…+260 °C), it is highly stable to chemic influences and has well anti friction behavior resulting in low friction coefficients. However, the relatively low wear resistance of PTFE in relative motion with steel counterparts makes it less suitable for use as a dry lubricant in highly loaded tribological systems. By mixing or bonding PTFE with other polymers (e.g. polyamide), compounds with improved wear behaviour are obtained.Part of the project will be the development and optimization of the compounds, among other things with regard to the size and distribution of the PTFE particles in the matrix as well as suitable adhesive groups on the mating body. Here various polyamides will be investigated as matrix polymers. The lubrication concept of the worm gear based on transfer lubrication is the use of a “sacrifice" part, made by a second worm wheel of compound with the solid lubricant (PA-PTFE-cb compound). A second part of the project is to analyze the transfer film on the metal worm and worm wheel. Around this, tribology tests with model configuration will be carried out with the PA-PTFE-cb compound material in contact with the metal parts as well as the buildup and testing of a prototype worm gear. Caused by the fluid-free lubrication the thermal transfer will be very different compared with oil lubricated worm gears. That is the reason for developing thermal models and the comparison to experimental results in the project.
DFG Programme
Priority Programmes
Co-Investigator
Dr.-Ing. Manuel Oehler
