DRY LUBRICANTS

Abstract

THE VERY TITLE of this talk is something which is always quite exciting to an Engineer—that is the thought of completely dry lubrication and the possibility of dispensing with such unpleasant necessitites as grease cups, nipples, oil sumps etc. Unfortunately, films of dry lubricants do have co‐efficients of friction and are therefore subject to wear, so the ideal of “life time lubrication” is still in the far and distant future. However new materials are constantly being discovered and/or developed which offer some technical advantage over the previous best, and as each of these materials comes to light it does mean that there are a few more engineering units that at one time were dependent on grease or fluid film lubrication that may now be dry lubricated. It is really the technical‐cum‐commercial development of dry lubricants that this paper discusses. For many years the use of Lamellar solids was limited to such materials as talcum, mica and graphite, the last being by far the most popular and possibly still the most widely used today. In more recent years, molybdenum disulphide has come very much to the fore, and because of certain technical advantages (which will be discussed later) will probably replace graphite if and when it becomes more economical to produce and if it in turn does not first become replaced by other lubricating solids such as boron nitride, tungsten disulphide and cadmium oxide. Of these “new” names in dry lubrication, tungsten disulphide looks very promising and has been selected as the third dry lubricant to discuss.