Soldering, Brazing , Welding, Lubrication, Bearings, Power Transmission
2nd Semester 2012-2013 - 2nd and 3rd Lecture - Journal Bearings and Lubrication
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Transcript of 2nd Semester 2012-2013 - 2nd and 3rd Lecture - Journal Bearings and Lubrication
4/6/2013
1
2nd and 3rd Lecture of Machine Elements 2
Ardi Noerpamoengkas, ST
Lubrications
Lubricants Classifications
Lubrications Functions
Forms of Lubrications
Types of Journal Bearings
Journal Bearings and Lubrication FormulationsFormulations
Lubrications Methods
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Lubricants Classifications
Liquid lubricants
Semi-liquid lubricants
Solid lubricants
Lubricants Classifications
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Lubricants Classifications
Lubrications Functions
Reducing wear
Reducing power losses
Carrying chips from metal erosion process
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Forms of Lubrications
Hydrodynamic lubrication
Hydrostatic lubrication
Elastohydrodynamic lubrication
Boundary lubrication
Solid-film lubrication
Types of Journal Bearings
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Journal Bearings and Lubrication Formulations Radial clearance (c)
Absolute viscosity (μ)
Kinematic viscosity (v)
Absolute viscosity at Test Temperature (Z)
Viscosity Index (%) Viscosity Index (%)
Frictional torque (Tf)
Load per projected area of journal (P)
Journal Bearings and Lubrication Formulations Bearing characteristic number (S’)
Heat lost (H)
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Journal Bearings and Lubrication Formulations Radial clearance (c)
c = rb – rj
rb = radius of bearing
rj = radius of journal
Look at Fig 8 3 Look at Fig 8.3.
Journal Bearings and Lubrication Formulations Absolute viscosity/dynamic viscosity (μ)
reyn (English Sys), poise (Metric Sys)
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Journal Bearings and Lubrication Formulations Kinematic viscosity (v)
v = kinematic viscosity (stokes)
absolute viscosity (poise) μ = absolute viscosity (poise)
ρ = mass density (kg/m3)
Journal Bearings and Lubrication Formulations Absolute viscosity at test temperature
(Z) in cp(Z) in cp
S = Saybolt Universal Seconds S = Saybolt Universal Seconds
ρt = Specific gravity at test temperature
ρt = Spesific grafity at 60 deg Fahrenheit
t = Test temperature (deg F)
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Journal Bearings and Lubrication Formulations Viscosity Index (%)
L = Visc. of standard 0% VI at 100 F
H = Visc of standard 100% VI at 100 F H = Visc. of standard 100% VI at 100 F
U = Visc. of unknown VI at 100 F
Look at Table 8.1.
Journal Bearings and Lubrication Formulations Frictional torque (Tf)
Tf = Frictional torque (lb.in) μ = Absolute viscosity (reyns) L L th f b i (i ) L = Length of bearing (in) r = Journal radius (in) n = journal speed (rpm) h = radial clearance (in)
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Journal Bearings and Lubrication Formulations Load per projected area of journal (P)
W = Journal load (lb)
r = Radius of journal (in) rj = Radius of journal (in)
L = Length of journal (in)
Journal Bearings and Lubrication Formulations Bearing characteristic number (S’)
n‘ = relative speed between journal and bearing (rps)bearing (rps)
P = Load per projected area of journal (psi)
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Journal Bearings and Lubrication Formulations Bearing characteristic number (S’)
n‘ = relative speed between journal and bearing (rps)bearing (rps)
P = Load per projected area of journal (psi)
Journal Bearings and Lubrication Formulations Viscosity-temperature chart for SAE
numbered oils (Fig 8 13 )numbered oils (Fig 8.13.)
Pressure variation around journal bearing (Fig 8.14.)
Minimum film thickness variable (Fig 8.15.)
Friction coefficient variable (Fig 8.16.)
Lubricant flow variable (Fig 8.17.)
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Journal Bearings and Lubrication Formulations Flow ratio (Fig 8.18)
Temperature rise variable (Fig 8.19.)
Journal Bearings and Lubrication Formulations Heat lost (H) in BTU/hr
C = heat transfer coefficient (BTU/(hr.ft2.F))
A = effective heat transfer area (ft2) A = effective heat transfer area (ft2)
tb = bearing housing temperature (deg F)
ta = ambient air temperature (deg F)
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Lubrications Methods
Wick-feed oiler
Drop-feed oiler
Ring-oiled
Splash-system oiled
Pump oiled / pressure fed systems
Literation References
Deutschmann. 1975. Machine Design, theory and practice Macmillantheory and practice. Macmillan Publishing Co., Inc.
Lansdown. Standard Handbook of Machine Design. McGraw-Hill
Budynas-Nisbett. Shigley’s Mechanical Engineering Design. McGraw-Hill