Lubrication Student Study Notes

Industrial Maintenance Chapter 9 p. 301- 304; Industrial Mechanics “Lubrication Chapter #13”

1. What is the purpose of lubrication? Maint p. 301

2. How thick is the fluid film that separates two surfaces when lubrication is occurring properly? (10 – 50) microns

3. List four purposes of lubrication. Maint p. 301 right column, Mech p. 351 left column

4. What is friction? Mech p. 348

5. What is sliding friction? What is rolling friction? Maint p. 301 right column

6. What is the difference between surfaces during the break-in period and after the break-in period? Maint p. 302 Fig 9-1

7. Why does most wear occur during machine start-up? Mech 354

8. Describe the purposes of five possible additives that can be added to a lubricant. Maint p. 302, left column, Mech p. 352

9. How does grease provide lubrication? Maint p. 302 – 303

10. What is grease made of? Mech 355 p. 365

11. What bad thing happens when grease reaches the dropping point temperature? Maint p. 303, Mech p. 359

12. How is grease applied to a machine? Mech 359, Fig 13-12

13. When might dry lubricants be used? Maint p. 303

1 14. How does a lubricant become contaminated? Maint p. 303 – 304, Mech p.359 -360

15. How will you prevent lubricants from becoming contaminated? Maint p. 304

16. Describe boundary and fluid film lubrication. Mech p. 348 Fig. 13-1, p. 349 -50

17. How does a speck of dirt destroy fluid film lubrication?

18. Oil is a liquid form lubricant produced from mineral oils (crude oil), and animal fats. Modern oils have many additives. Additives wear out, not oil, therefore oil can be recycled. Synthetic oil made of chemical compounds, expensive, high temperature use, do not mix with mineral oils.

19. Define viscosity. Mech p. 353

20. What happens to a lubricant’s viscosity as temperature rises and falls?

21. What is viscosity index? Mech p. 353

22. What is the pour point of oil?

23. What is the flash point of oil?

24. What is the fire point of oil?

25. Explain the SAE rating from thinner to thickest? Mech p. 354

26. What problems can result from using synthetic lubricants? Mech p. 354

27. What health and safety problems can lubricants cause?

28. Briefly describe 6 methods of applying oil. Mech 357 – 358, Fig.13-11

2 29. How would you set up and run a world class (really good) lubrication system for a small to medium sized plant? (Not in the book.)

30. List three things you can learn from oil analysis. Mech p. 360

31. How will you take accurate and uncontaminated oil samples DVD

The steps of selecting the correct lubricant.

1. Depends on the operating characteristics of the machine, speed, temperature, water (wash down) dirty environment, duty cycle. 2. Select lubricants based on manufacturer’s specifications if the conditions are within normal operation. 3. Consult lubricant manufacturer or equipment manufacturer for suggestions if the operating conditions are out of the ordinary. 4. Lubricant selection always a compromise between, cost and most effective application.

Example: Air compressor oils must work within operating temperatur e range of the compressor, winter and summer. If the viscosity is to o high the oil will not spread and will cause drag and poor lubricatio n. If the viscosity is too low it will not maintain fluid film. Will need lo w flash point oil that does not carry lots of carbon, but that oil may n ot be viscous enough. Additives added and compromise oil is select ed. If a general purpose grease is used, make sure you have high a nd low temp types.

Grease a zerk fitted bearing. Steps:

1. General rule: Do not over-grease. Follow manufacturer's recommen dations. 2. If fitted, remove zerk fitting cap. Clean zerk fitting with lint free rag. 3. Clean grease gun fitting with same rag. 4. Slowly, with machine running if possible, apply prescribed amount of grease.

3 5. Remove grease gun fitting. 6. Leave a small dab of grease on the fitting. Replace zerk cap.

Safety: Caution around moving parts. Eye protection. Rubber gloves if indicated on MSDS.

Do not over grease bearing. About 30-40% full is optimum.

Too much grease causes channeling and stirring, heat generated destroys lubricating properties.

Use only one type of grease with each gun. Even if the canister is empty some grease remains in the gun and hose.

Use some method of color coding what grease or other lubricant is required for each machine lubrication point.

What are the formulae for determining the amount of grease required and frequency for relubricating a bearing? (DVD)