Influence of contact pressure and sliding speed on the temperature and coefficient of friction in sliding contact between two PET samples

Abstract

Original scientific paper The use of polymeric materials has been growing steadily. A more extensive use of polymers as bearing materials will be made possible by a better knowledge of the properties of particular materials and their compatibility in a particular application. Poly(ethylene terephthalate) (PET) with the addition of Polytetrafluorethylene (PTFE) shows potential for being used as a material for machine parts rotating at lower loads due to its good ratio between manufacturing costs and mechanical properties. The use of PET in a PET/PET combination has been tested in three working points, with a lubricant applied once in each run and with three different values of sliding speed and of load. The change in temperature which occurs in the vicinity of the outlet zone of the contact at the end of the sliding path after 9 hour operation is presented. The applied method and temperature measurement are explained. The distribution of obtained maximum and average temperatures in the load range 9 ÷ 18 MPa and the sliding speed range 0,8 ÷ 2 m/s is shown for single working points. In addition, the effects of lubricant application on the increase in the magnitude of the load carrying capacity and on the decrease in the value of friction coefficient are shown in comparison with the reference values of temperature and friction coefficient in the dry contact operation. Keywords: flash temperature; friction; load; PET; sliding Utjecaj kontaktnog pritiska i brzine klizanja na temperaturu i faktor trenja u kontaktu s uzorcima od PET-aIzvorni znanstveni članak Upotreba polimernih materijala u stalnom je porastu, područje primjene polimera kao ležajnog materijala povećat će se boljim poznavanjem karakteristika pojedinih materijala te njihove kompatibilnosti u određenim primjenama. Primjena polietilen tereftalata (PET) s dodatkom politetraflouretilena (PTFE) zbog omjera proizvodnih troškova i mehaničkih svojstava pokazuje potencijal u primjeni kod strojnih dijelova u rotaciji pri nižem opterećenju. Primjena PET-a u kombinaciji PET/PET ispitana je u tri radne točke uz jednokratnu primjenu maziva kod tri različita iznosa obodnih brzina i opterećenja. Prikazana je promjena temperatura koja se javlja u području neposredno nakon izlaza iz zahvata ispitnih uzoraka tijekom rada za ukupni prijeđeni put u trajanju od 9 h, uz obrazloženje metode mjerenja temperature. Za pojedine radne točke prikazana je raspodjela dobivenih maksimalnih i srednjih temperatura prema opterećenju od 9 do 18 MPa te za područje obodnih brzina od 0,8 do 2 m/s. Prikazan je utjecaj maziva na povećanje opteretivosti i smanjenje faktora trenja primjenom maziva uz referentne vrijednosti temperatura i faktora trenja pri radu na suho.

An Experimental Study of Composite Plain Bearings: The Influence of Clearance on Friction Coefficient and Temperature

“…At a higher load level, values were 1 MPa and 2.5 MPa, respectively. It should be added that a study carried out by Domitran, et al [25], in which the authors used polyethylene (PET) samples with the addition of PTFE, has shown that an increase in contact pressure also increased the friction coefficient. Building on these premises, an increase in contact pressure could affect the increase in friction coefficient in lower clearance sizes.…”

“…The contactless thermometer (declared accuracy of ±1%) was used to measure the plain bearing temperature ϑ. The disadvantages of using the above-described method to determine the polymer temperature are shown in [25].…”

Comprehensive Analysis of Different Coating Materials on the POM Substrate

“…Firstly, the mass production of polymeric machine parts and structural components is more cost-effective, especially when utilising injection moulding. Secondly, the use of additional lubrication is not necessary for contacting polymeric machine parts, such as gears and bearings, making them a compelling choice for applications where the use of lubricant is inadequate (e.g., printers, medical instruments) [ 5 , 6 ]. Furthermore, polymers exhibit significant resistance to corrosion, enabling their operation in environments where corrosive substances are found [ 7 , 8 ].…”