On the use of laboratory friction tests to select lubricants for cold rolling of aluminum alloys (c)

Laboratory friction devices such as the four-ball wear tester; pin-on-flat or pin and V-blocks lubricant test machine are often used to compare the ef ficiency of metalworking lubricants. More sophisticated tests such as the t wist compression and ring compression tests have been developed. The main d isadvantage of all these rests Is that the contact conditions are not repre sentative of metalworking operations. During cold rolling, the alloy is stretched and fresh surface is constantly in contact with the components of the lubricant. Additives such as fatty a lcohols, acids or esters react with the surface and modify the friction con ditions. During the laboratory tests, little or no new surface is generated . Experiments were conducted with typical lubricants for aluminium cold rolli ng on a pin on flat reciprocating device, on a specific laboratory rolling simulation test and on a rolling mill. The results evaluated in terms of fr iction coefficient (laboratory tests) or maximum reduction (rolling trials) show that the classification of the lubricants depends strongly on the tes t method. The field test on the mill remains unavoidable.