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FINAL EXAM 322 > Machining Fundamentals > Flashcards

Machining Fundamentals Flashcards

week 8

1
Q

In machining is there a wastage of material?

A

Yes

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2
Q

Machining

A

material removal by a sharp
cutting tool, e.g., turning, milling, drilling

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3
Q

Abrasive processes

A

material removal by hard, abrasive particles, e.g., grinding

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3
Q

Nontraditional processes

A

various energy forms other than sharp cutting tools to remove material

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4
Q

What is a chip

A

whatever material removed is called a chip

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5
Q

cutting action involves sheer deformation of material to form a _____.

A

chip

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6
Q

why is machining important?

A
  1. good dimensional accuracy and surface finish
  2. variety of work materials
  3. variety of part shapes and special; geometric features
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7
Q

disadvatage with machining

A
  1. wastage of material (chip)
  2. Time consuming (removed layer by layer)
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8
Q

where is machining in the manufacturing sequence?

A

generally performed after other manufacturing processes (casting, forging, bat drawing)

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9
Q

what are the types of machining operations

A

Common machining types:
*Turning
*Drilling
*Milling

Other machining types:
*Sawing
*Shaping and planing
*Broaching
*Grinding

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10
Q

What is turning operation

A

work peice is rotating and cutting tool provides feed (single point cutting)

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11
Q

Flat turning feed:

A

tool is fed parallel to the work axis

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12
Q

what is drilling

A

tool is rotating and speed depends on tool diameter

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13
Q

drilling feed

A

parallel to tool axis

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14
Q

depth of cut is the

A

depth of the hole

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15
Q

drilling is a

A

multi point cutting

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16
Q

what is milling

A

tool is turniing (defining surface speed)

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17
Q

in milling surface velocity depends on

A

diameter of the tool

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18
Q

depth of cut in milling

A

tool penetrates beneath original work surface (multi point cutting )

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19
Q

feed of milling

A

work feeds in the direction perpendicular to tool surface

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20
Q

which operations are single point cutting

A

turning

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21
Q

which operations are multi point cutting

A

drilling and milling

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22
Q

what is rake face

A

directs flow of new chips - at an angle called rake angle

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23
Q

what does flank of the tool provide

A

provides the clearence berween the tool and the new work surface - at an angle called relief/clearance angle

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24
Q

what is cutting speed (m/sec or ft/min)
- v

A

relative motion between tool and work piece (primary motion)

25
Q

what is feed (mm or inch)
- f

A

tool is moved laterally across the work (secondary motion)

26
Q

depth of cut (mm or inch)
- d

A

penetration of cutting tool below original work surface

27
Q

Roughing vs. Finishing

A

Roughing - removes large amounts of material (gets close to wanted geometry)

Finishing- completes part dimensions (final dimension, tolerances and finishes)

28
Q

what are the required settings for roughing

A

high feeds and depth, low speeds

29
Q

what are the required settings for finishing

A

low feeds and depths, high speeds

30
Q

what is cutting fluid used for

A

applied to cool and lubricate the tool (depends on work material and tooling)

31
Q

define sheer strian

A

deflection of the element over orthogonal distance over which deformation occurs

32
Q

primary shear zone

A

where deformation of material takes place

33
Q

secondary shear zone

A

due to friction between the chip and the tool (tool chip interface)

34
Q

4 types of chips

A
  • Discontinuous chip
  • Continuous chip
  • Continuous chip with buildup edge
  • Serrated chips
35
Q

continuoes chip

A

good finish
- ductile material
- high cutting speed or high rake angle
- small feed and depth of cut

36
Q

problem of continuoes chip

A

chip disposal and tangling about the tool (chip breakers are usually used)

37
Q

when does a build up edge happen

A

when heat is being accumalted and the melts onto the cutting tool

38
Q

continuous chip with build up edge (BUE)

A
  • ductile material
  • low to medium cutting dpprf
  • local high temp and extreme pressure in the cut zone cause parts of material to stick to rake face of the tool near the cutting edge (BUE)
39
Q

problems of continuous chip with build up edge (BUE)

A
  • reduces toool life time
  • rough surface finish (BUE on work surface)
40
Q

advantages of continuous chip with build up edge (BUE)

A

thin stable bue protects the tool surface

41
Q

reduce built up edge chips

A
  1. increase cutting speed
  2. decrease the depth of cut
  3. increase rake angle
  4. use a sharp tool
  5. reduce friction with a cutting fluid
42
Q

serrated chip

A

material difficult to machine (titanium alloy, nickel-based superalloys)
- high cutting speed
- have a saw tooth appearance (alternate high and low shear strain surface; irregular texture)

43
Q

Discontinuous chip

A
  • brittle material (cant undergo higher shear strain)
  • low cutting speed, large feed and depth of particles, low rake angle, lack of good cutting fluid, low stiffness of machine tool, high tool chip friction
    irregular texture
44
Q

problems of discontinuous chip

A

machine tool vibrates and chatter
causing
1. bad surface finish and accuracy
2. wear on cutting tool

45
Q

solution for discontinuous chip

A

high cutting speed, high temperature and a more ductile material

46
Q

what are the forces in cutting metal

A

friction force (F), Normal force to friction (N), shear force (Fs), Normal force to shear (Fn)

47
Q

what forces can be measured

A

cutting force and thrust force

48
Q

Friction force F

A

friction force between tool and chip resisting the flow of chip along the rake face

49
Q

Normal force to friction N,-

A

force normal to the friction
force

50
Q

Shear force, Fs -

A

force that cause shear deformation in the shear plane

51
Q

Normal force to shear, Fn

A

normal to shear force

52
Q

Cutting force Fc

A
  • direction of cutting
53
Q

Thrust force, Ft

A
  • perpendiculat to
    cutting force
54
Q

resultant force consists of…

A

thrust force and cutting force
OR
frictional force and normal force perpendicular to friction force

55
Q

thrust force, Ft is positive or negative depending on the _______

A

rake angle

56
Q

what is the merchant’s assumption

A

the shear angle will form to minimize energy

57
Q

when the shear angle increases

A

shear length decreases and less energy is needed and vice versa

58
Q

heat is difused to

A

chip (ideal)
work peice
cutting tool

59
Q

what does is the surface roughness defined by

A
  1. radius of cutting tool
  2. feed rate
60
Q
A

FINAL EXAM 322 (5 decks)

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