Lubrication

Question 1

What is friction?

Answer 1

Is the tendency to resist movement when two surfaces are in contact as they move.

Question 2

List the negative effects of friction.

Answer 2

• increases power consumption
• causes wear
• creates heat reducing component life

Question 3

Name the three types of friction?

Answer 3

• sliding friction
• rolling friction
• fluid friction

Question 4

What type of friction exists within a lubricant?

Answer 4

Fluid friction.

Question 5

What are the functions of a lubricant?

Answer 5

• stop corrosion
• reduce heat
• carry away contaminants
• help seal
• reduce friction (wear)

Question 6

Describe Full Film lubrication.

Answer 6

Completely separates surfaces with a continuous film.

Question 7

What is Sliding Friction?

Answer 7

When two surfaces slide over each other.

Question 8

Describe Boundary Film lubrication.

Answer 8

A film that does not completely separate the surfaces.

Question 9

How does a lubricant reduce friction?

Answer 9

By separating two surfaces with a film that has less friction than the moving parts.

Question 10

What is Rolling Friction?

Answer 10

When a spherical or cylindrical body rolls over a surface.

Question 11

What is the Theory of Adhesion?

Answer 11

Adhesive forces cause “unlike” materials to stick together.

Question 12

What is the Theory of Cohesion?

Answer 12

Cohesive forces cause molecules of “like” materials to stick together.

Question 13

Oil forms in layers of ________.

Answer 13

Globules.

Question 14

What is Viscosity?

Answer 14

The resistance to flow.

Question 15

What five things should be considered when choosing the right viscosity lubricant?

Answer 15

• speed (RPM)
• load
• temperature
• pressure
• environment

Question 16

What does higher viscosity allow?

Answer 16

Greater loads to be carried.

Question 17

What should be done to minimize power loss?

Answer 17

Use the lowest viscosity oil that is able to carry the load.

Question 18

Name the two ways viscosity is measured?

Answer 18

Dynamic and Kinematic.

Question 19

Dynamic viscosity is use to measure __________.

Answer 19

Fluid friction.

Question 20

What is the most common British unit of Kinematic viscosity?

Answer 20

Centistoke (cSt).

Question 21

Viscosity changes due to temperature are indicated by the __________.

Answer 21

Viscosity Index (VI).

Question 22

What does a higher Viscosity Index number mean?

Answer 22

The smaller the change in viscosity due to temperature.

Question 23

What are the three main groups Additives and Inhibitors are divided into?

Answer 23

• air control
• water control
• load capacity

Question 24

What is Demulsibility?

Answer 24

The ability of petroleum to separate from water upon standing.

Question 25

What is Emulsibility?

Answer 25

The ability of petroleum to mix with water using a special emulsifying agent.

Question 26

Additives that reduce wear by polishing contacting parts are called ___________.

Answer 26

Anti-wear Additives.

Question 27

Additives used for heavy load or shock load conditions are called __________.

Answer 27

Extreme Pressure Additives (EP).

Question 28

How is grease usually made?

Answer 28

By thickening lubricating oils with "soap".

Question 29

What is the "soap" content for general use greases?

Answer 29

Between 7% - 18%. (Specialty grease can range from 3% - 50%).

Question 30

Greases made by combining a fatty acid and a base metal are called __________.

Answer 30

Simple Soap Greases.

Question 31

Name the five base metals used in simple soap greases.

Answer 31

- calcium - sodium - aluminum - lithium - barium

Question 32

How is grease consistency measured?

Answer 32

Penetration Numbers.

Question 33

What does NLGI stand for?

Answer 33

National Lubricating Grease Institute

Question 34

What is Dropping Point when referring to grease?

Answer 34

Is the temperature at which a grease becomes fluid.

Question 35

When in a bearing, grease "shears" into thin layers and follows rotation. This is called what?

Answer 35

Directional Fluidity.

Question 36

Which is the best lubricant for heavy loads at low to medium speeds?

Answer 36

Grease

Question 37

Which is the best lubricant for high to very high speeds?

Answer 37

Oil

Question 38

When machining what is the main purpose of the lubricating cutting fluid?

Answer 38

To reduce friction.

Question 39

Which cutting oil should only be used on ferrous metals?

Answer 39

Active oil.

Question 40

Which cutting oil is used on both ferrous and non ferrous metals?

Answer 40

Inactive oil.

Question 41

What are the positive effects of friction?

Answer 41

- provides traction - allows a means of polishing - used to start, accelerate and stop machines - promotes accurate tracking in bearing raceways

Question 42

What is elasto-hydrodynamic lubrication?

Answer 42

A lubricant film that forms under a loaded rolling element.

Question 43

What is the United States kinematic unit of viscosity measured by a Saybolt Viscometer?

Answer 43

Saybolt Universal Seconds. (SUS or SSU)

Question 44

What is Absolute Viscosity and how is it measured?

Answer 44

A direct measurement of the force of resistance to flow measured in centipoises.

Question 45

What is Flashpoint?

Answer 45

The lowest temperature at which the vapor above the oil will ignite with a flame passed over it.

Question 46

What type of oil was developed to solve lubricating problems that petroleum oils can't?

Answer 46

Synthetic oil.

Question 47

What are Additives?

Answer 47

Chemicals added to the base oil to enhance performance of the oil under specific operations.

Question 48

What are Oxidization Inhibitors?

Answer 48

Additives in the oil that work to inhibit the process of oxidization.

Question 49

What are Anti-wear additives?

Answer 49

Additives that combine chemically with the surface of the metal to form a protective coating.

Question 50

What are the functions of Detergent Additives?

Answer 50

- keeps sludge and fine deposits off metal surfaces - anti wear and anti scuff properties - clean existing deposits - rust inhibitor - controls acid

Question 51

What is the most common Solid Additive and what is its purpose?

Answer 51

Graphite and it is used as an anti-wear additive.

Question 52

What is the purpose of Pour Point Depressants?

Answer 52

To make oil flow easier at lower temperatures.

Question 53

What is the function of a Demulsifier?

Answer 53

To separate water from oil.