Presentation on theme: "Lubrication Training - Basics of Lubrication Types of Lubrication Hydrodynamic Boundary Mixed."— Presentation transcript:
Lubrication Training - Basics of Lubrication
Types of Lubrication Hydrodynamic Boundary Mixed
Hydrodynamic Lubrication Occurs when machine parts are completely separated by a full and continuous film of lubricant Contact between the parts does not occur. Full-fluid-film lubrication is hydrodynamic lubrication, the oil adheres to the moving part and is drawn into the area between the rotating surfaces, where it forms a pressure, or hydrodynamic, wedge. A less common form of full-fluid-lubrication is hydrostatic lubrication, where the oil is supplied to the bearing area under pressure to separate the sliding surfaces.
Boundary Lubrication Under certain conditions such as shock loading, heavy loads, high temperature, slow speed and critically low viscosity, the lubricant is no longer hydrodynamic Frequent contact between the surfaces, resulting in a significant rise in temperature and subsequent destruction of the contacting surfaces. Under these circumstances, the fluid film is no longer capable of adequately protecting the surfaces. EP capabilities in the lubricant are essential Solid additives are mixed into the grease
Mixed Lubrication Although not a true “mode” of lubrication in the sense of hydrodynamic or boundary, mixed lubrication occurs more frequently then is realized. Mixed lubrication is a transitional mode of lubrication between hydrodynamic and boundary Mixed lubrication is characterized by the likelihood of intermittent surface contact EP and anti-wear are essential properties in the lubricant
Select a base fluid: MINERAL OIL or SYNTHETIC FLUID? How is a lubricant made?
Selecting a base fluid: MINERAL OIL Paraffinic or Naphthenic Readily available Comparatively low cost Limited performance.
Selecting a base fluid: SYNTHETIC FLUIDS PAO, PAG, Ester Synthetically manufactured Comparatively high cost Improved performance Longevity Temperature Viscosity Index
Selecting a base fluid: OTHER SYNTHETIC FLUIDS Silicones Fluorinated Ultra Performance Ultra Temperature Long Life Lube for Life
Base fluid selected: Mineral or Synthetic NOW SELECT THE REQUIRED VISCOSITY.
Selecting the required viscosity: Generally thinner fluids are used for: Lighter loads Faster speeds.
Selecting the required viscosity: Generally thicker fluids are used for: Heavier loads Slower speeds So how do we measure viscosity?.
Low Viscosity (Thin) High Viscosity (Thick) mm 2 per second =centistokes (cSt) 40 0 C & C
What are the units of viscosity? mm 2 s = centistokes (cSt) = ISO VG (at 40 0 C) 32 cSt - typical low viscosity (thin) 680 cSt - typical high viscosity (thick) ISO VG etc
Lithium soap Calcium soap Aluminium soap Lithium complex Calcium complex Aluminium complex Improved Performance -Temperature -Mechanical stability General Purpose Soap Thickeners Thickener Systems – turn fluids into greases
Thickener Properties Lithium Good multi-purpose, good mechanical stability, limited other properties Lithium Complex Excellent high temp & mechanical stability capability Calcium Complex Excellent load carrying and water resistance Aluminium Complex Excellent temperature capability & water resistance
Other grease thickeners: Bentonite clay Silica PTFE. Other Thickener Systems
NLGI PENETRATION TEST NATIONAL LUBRICATING GREASE INSTITUE of America. How is the grease thickness checked ?
SEMI FLUID/ FLUID GREASE NLGI Numbers - WHAT DO THEY MEAN? Generally applied by Automatic Lubricator NLGI No 6BLOCK GREASE Old Technology NLGI No 5SEMI-SOLID ELASTIC-LIKE GREASE Very rarely used, but can be found in marine or shipping applications NLGI No 4VERY TACKY GREASE Rarely used now, but found sometimes found in heavy open gears or mining equipment NLGI No 3HEAVIER GREASE Used mainly for hand applied or caulking guns NLGI No 285% OF MARKET Generally used in grease guns NLGI No 1THINNER GREASE Generally used in grease guns, slightly more pump- able for short pipe lines NLGI No 0TREACLE LIKE GREASE Used in semi-auto and auto systems with shorts pipelines NLGI No 00SEMI FLUID GREASE Used in semi-auto and automatic systems NLGI No 000 FLUID GREASE Used in some gearboxes and semi & auto lube systems with longer pipe lines
NLGI 6 NLGI 5 NLGI 4 NLGI 3 NLGI 2 NLGI 1 NLGI 0 NLGI 00 NLGI 000 HOW IS GREASE THICKNESS MEASURED? Premium EP 1Premium EP 2Premium EP 000
Summary Base fluid Mineral or synthetic Viscosity EP additives Chemical and/or solids Corrosion inhibitors Oxidation inhibitors Thickeners for greases.
TO SUPPORT A ROTATING SHAFT Outer Race Inner Race Balls or Rollers Lubricant Shaft BASIC FUNCTION OF A PRECISION BEARING
BASIC FUNCTION OF A PLAIN BEARING TO SUPPORT A ROTATING SHAFT Plain Bush Lubricant Shaft
BASIC FUNCTION OF A SLIDE TO SUPPORT A SLIDING LOAD
FRICTIONAL HEAT ALL BEARINGS/SLIDES HAVE ONE SURFACE MOVING AGAINST ANOTHER WHY LUBRICATE?
FRICTIONAL HEATFRICTIONAL WEAR
Introduction of a lubricant film REDUCES FRICTIONAL HEAT & WEAR BASIC FUNCTION OF A LUBRICANT.
Reasons for bearing failure
Breakdown of “improper lubrication” section
Standard grease gun can develop 3,000 psi High pressure grease guns can develop >6,000 psi Potentially resulting in excessive drag causing: Increased power demand Ball/roller skid Increased friction Excessive heat Excessive race wear Degradation of the lubricant. Potential failures due to over lubrication
Correct Application of a lubricant LITTLE & OFTEN! Precision Bearings: Typically fill 1/3 to 1/2 of vacant area in bearing High speed bearings require approx. 1/3 fill Plain Bearings Typically fill until clean grease shows.