RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Chapter 5 – The Role of Tribology in Engineering Materials Tribology comprises the science and technology of interacting surfaces in relative motion; that is, friction, lubrication and wear. Tribology is a vast and interdisciplinary subject, ranging from the fundamental physics of surface contact and adhesion to the application of advanced materials and lubricants to solve practical industrial friction and wear problems.

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Motivation: Most common forms of metal failure: –Corrosion –Fatigue (cyclic loading) –Wear (surface abrasion due to excessive friction or lack of lubrication) = TRIBOLOGY –CASE STUDIES (my own)

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall What is Friction Force tangential to the interface of two contacting bodies = Ff. –Dynamic and static –Dynamic produces heat Friction Force Coefficient of friction  s and  d Normal Force Assumptions: Ff independent of contact area,  = constant

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall More Complicated Models Exist: Contact Mechanics In actuality, as N increases, contact area increases, thereby affecting .  is a non- linear function of N. What else might  vary with??

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall More Complicated Models Exist: F = Fa + Fp + Fs + Fn

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall What about contact stresses??? Recall: Pitting stress in gear teeth

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall How to Measure  ??? Do you want  s or  d ??? For most stress analysis want  s – why??

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Good for measuring  s. You should know how to derive this. Good for measuring  s and  d.

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Typical Friction Force Curves  s = Fa/N  d = Fb/N Stick- Slip – difficult to get a 

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Figure 3-8: Average n for various materials in reciprocating motion of an annular ring rider (.1 sq in) on a type 316 stainless steel counter face at 20 C 50% relative humidity at various normal forces. The stroke was 50 mm and the frequency was 0.5 Hertz. The friction force was averaged for eight cycles for each test.

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall CASE Study: Compression seal. Coefficient of friction was key for proper design and analysis.

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Friction Testing – Slide flat EPDM samples across ABS slab CASE Study

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Coefficient of Friction Results: Incumbent Material = 0.15, 0.13 M-858-2(2) = 0.23, 0.17 M-858-2(6) = 0.30, 0.30 M-858-2(7) = 0.24, 0.21 M-858-2(8) = 0.23, 0.22 M-858-2(9) = 0.37, 0.38 M-858-2(10) = 0.31, 0.31 M-858-2(12) = 0.36, 0.33 M-858-2(13) = 0.25, 0.29 M-858-2(14) = 0.29, 0.25 M-858-2(15) = 0.21, 0.24 M-858-2(16) = 0.21, 0.28

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall 4” seal section shown Actuator Force/Disp lacement Fixed to load frame ABS Polycarbonate Test Set-up for K and Stress Relaxation: Seal glued with 3M CA40H Adhesive

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Load Only

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Note, modified seal slightly stiffer at lower deflections and softer at higher deflections!

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Stiffness Summary:

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall WEIGHT USED: SLED + 1LB WEIGHT (704g)

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall 5.4 Definition of Surface Wear Wear - Damage to a solid surface involving progressive loss of material due to contact and relative motion with another surface. 13 types of wear!! Erosion – Damage to a solid surface involving progressive loss of material due to mechanical interaction between that surface and a fluid, impinging liquid or solid particles. 5 kinds of erosion

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Figure 5.14 – Major Categories of wear and specific types of wear in each category.

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Types of Wear: Figure 5:20 – Adhesion wear – localized bonding between contacting surfaces Figure 5-21: Galling wear – severe adhesion actually leads to material flow up from the surface. adhesion

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Figure 5-23: Fretting wear of splined shaft– small oscillatory motion abrades surface – looks like rust – surface looks pitted. adhesion

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall F5-24: low stress abrasion wear – bushing sliding on shaft abrasion

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Surface fatigue F 5-27 – Pitting surface fatigue – large roller thrust bearing race – compressive stress developed between roller bearing and race = pitting. Material actually fatigued and removed from surface!!

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Surface fatigue F5-28: Impact wear

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Surface fatigue F 5-30: Brinelling – brinelling of bearing race due to static overload. Note brinelling more of a static failure (indentation) versus fatigue or wear failure.

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall F 3-27: Factors that affect wear at various size levels. Key: Bonds between atoms! Key: Dislocation s Key: Grain Size Key: Surface asperities Key: Surface confromanc e

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Figure 5-15: Types of Erosion – Note all involve fluids or smoke (particulates)

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Fig5– 16: solid particle erosion due to fly ash. Types of Erosion 5-17: Slurry erosion due to pumping slurry mixture of silica and water erosion

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Case Study – WEAR Requirement: Coat steel flight bars on conveyor of continuous miner with “soft” material for noise reduction. Must meet life requirement of 500,000 tons of coal (min) without significant wear.

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Joy Continuous Mining Machines 14CM series targeted for noise reduction 14CM Series12HM Series12CM Series 2010 SME Annual Meeting & Exhibit Phoenix, Arizona

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Commitment to Health & Safety Industry Leading Dust and Noise Reduction Initiatives Wethead Cutterhead SystemDual Sprocket Conveyor 2010 SME Annual Meeting & Exhibit Phoenix, Arizona

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Ongoing Developments Coated Dual Sprocket Chain 2010 SME Annual Meeting & Exhibit Phoenix, Arizona

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Figure 7-14 – abrasion wear of various plastics

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Taber Test – common test for abrasion resistance of elastomers/polymers

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall Compound No.Rheometer DataOriginal Physical PropertiesAfter Aging 70 hrs at 70°CCompression SetTaber MlMhts1tc90 tan Mh Cure Time Cure Temper ature 100% Modulu s Elong ationTensile Duro meter ∆ 100% Modulu s ∆ Elong ation ∆ Tensile ∆ Duro meter Cure Time Cure Temper ature °C mg loss per rev. XM-AR (1) m35s m35s XM-AR (2) m20s m20s XM-AR (3) m11s m11s XM-AR (4) m55s m55s XM-AR (5) m21s m21s XM-AR (6) m0s m0s XM-AR (7) m45s m XM-AR (8) m22s m22s XM-AR (9) m14s m14s XM-AR (10) m37s m37s Incumbent Mat'l0.0154

RJM, 9/16/06All photos and figures - Copyright, Prentice Hall 300,000 tons Key Property: Abrasion resistance?? Tear Strength?? Coef of Friction??