Machinery Lubrication

ML_Jan_Feb_Digital_Edtion

Machinery Lubrication magazine published by Noria Corporation

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32 | January - February 2017 | www.machinerylubrication.com ll lubricants contain a base oil. It serves as the foundation of the lubri- cant before it is blended with additives or a thick- ener in the case of a grease. But how do you know which base oil is best? Trying to choose between mineral oils and synthetics can be confusing. This article will break down the complexity between base oil formulations so you can make the right decision for each application. Base Oil Categories Lubricants can be categorized in many different ways. One of the most common classifications is by the constituent base oil: mineral, synthetic or vegetable. Mineral oil, which is derived from crude oil, can be produced to a range of qualities associated with the oil's refining process. Synthetics are man-made through a synthesizing process and come in a number of formula- tions with unique properties for their intended purpose. Vegetable base oils, which are derived from plant oils, represent a very small percentage of lubricants and are used primarily for renewable and envi- ronmental interests. Base Oil Characteristics All base oils have characteristics that determine how they will hold up against a A Benne t t Fi t ch | Nori a Corpor at ioN LESSONS IN LUBRICATION Understanding the Between DIFFERENCES BASE OIL FORMULATIONS SYNTHETIC STRENGTHS WEAKNESSES Polyalphaolefins (PAOs) Maximum Operating Temperature: 270°F/132°C High VI, high thermal oxidative stability, low volatility, good flow properties at low temperatures, nontoxic and compatible with mineral oils Limited biodegradability, limited additive solubility, seal shrinkage risk Diesters and Polyolesters Maximum Operating Temperature: 360°F/182°C Nontoxic, biodegradable, high VI, good low-temperature properties, miscible with mineral oils Low viscosities only, bad hydrolytic stability, limited seal and paint compatibility Phosphate Esters Maximum Operating Temperature: 240°F/116°C Fire resistant, biodegrades quickly, excellent wear resistance and scuffing protection Low VI, limited seal compatibility, not mis- cible with mineral oils, moderate hydrolytic stability Polyalkylene Glycols (PAGs) Maximum Operating Temperature: 300°F/149°C Excellent lubricity, nontoxic, good thermal and oxidative stability, high VI Additives marginally miscible, not miscible with mineral oils, limited seal and paint compatibility Silicones Maximum Operating Temperature: 450°F/232°C Highest VI, high chemical stability, excellent seal compatibility, very good thermal and oxidative stability Worst mixed and boundary film lubrication properties, not miscible with mineral oils or additives When you are choosing a base oil, there will be tradeoffs in the lubricant properties required for the application. S y n t h e t i c L u b r i c a n t s

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