Most closely associated with the fluoropolymer, polytetrafluroethylene is Teflon. PTFE is one of the most widely recognized compound used throughout the world with its exceptional release or non-stick, low friction or dry lubrication. It is recognized for its high thermal stability, it is formed by free radical vinyl polymerization of tetrafluoroethylene. Typical, though higher temperature can be satisfactorily sustained for shorter duration with the continuous service temperature of 500 degrees Fahrenheit. Flexibility at low or cryogenic temperature, abrasion resistance and mechanical toughness are mechanical properties included. By internal or external material reinforcements, keep in mind that wear factors can be dramatically improved, especially true using PTFE dispersion.
A reported coefficients of friction as low as 0.02 to 0.04 for non-lubricated mechanical systems. Coefficient of friction of 0.01 or less are attainable even at higher dynamic PV limits. The load, rates of travel, distance, surface finish, temperature and other system-dependent parameter will make the results vary. An exceptionally low friction, in otherwise non-lubricated environments, at lower surface velocities, pressures greater than 5 pounds per square inch that its resins can exhibit. Under all pressure conditions, curiously, friction actually increases with sliding speed up to 100 feet per minute. But the one that prevents stick-slip tendencies is this phenomenon. Anti squeak or no noise even at the highest speed are other benefits included. For example, sliding velocity has little effect on friction at combinations of pressure and velocity below the composition's PV limit above 150 feet per minute. With increasing pressure, its static friction resins decrease.
The maximum combination of pressure and rub-velocity that materials can operate continuously without lubrication is defined by PV limits. PV limits approach zero at temperatures between 550 degrees Fahrenheit and 600 degrees Fahrenheit for PTFE. It must be taken into account the composition's wear characteristic and allowable wear for the application in a useful PV limits. You must consider creep or cold flow when considering this type of teflon service for dry lubrication, low friction. With time called creep or cold flow, generally, a plastic material subjected to continuous load experiences a continued deformation. Even at room temperature or below, deformation is significant, hence, the name cold flow.
The total deformation under stress after a specified time in a given environment beyond that instantaneous strain which occurs immediately upon loading defines the creep. Time under load, temperature and load or stress level are independent variables affecting creep. Performance is sustainable, so as long as the stress level is below the elastic limit of the material. Creep is small and maybe neglected for many applications beyond a certain point. There is comprehensive recovery from various percentages of strain in many cases too. Where the original strain does not exceed the yield strain will nearly complete.
In a pure homogeneous state that much of this information pertains to dupont teflon PTFE. Information presented here does not account for composites of PTFE available today should be kept in mind. Internal binders, co-polymers or fillers are various reinforcement used to create its composites included. While anodize, plating, thermal spray, or advanced coating processes are external forms of its reinforcements. Therefore, its capabilities should be understood. With Teflon non-stick coatings, soon, you will be on your way to surface engineering.