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Manufacturing Processes > Manufacturing Processes > Flashcards

Manufacturing Processes Flashcards

1
Q

In how many directions can a milling machine be used to remove material from the work part?

A

Milling allows you to move the tool up and down (z direction) while you move the work piece in the x and y directions, meaning you are able to shape the piece in 3D space.

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2
Q

In how many directions can a lathe remove material?

A

Turning on a lathe removes material in 2D space for a cylinder, so in the axial and radial directions.

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3
Q

In how many directions can a drill press remove material?

A

Drill presses can only remove material in the z direction.

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4
Q

What is another name for face milling?

A

End milling

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5
Q

What are others name for peripheral milling?

A

surface, slab, form, or plain milling

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6
Q

How does peripheral milling differ from face milling?

A

Peripheral: the milling bit is oriented paralell to the work piece and rotates clockwise while the work piece is fed through. Best way to describe this is like a rolling pin.

End: The milling bit is oriented perpendicular to the work piece.

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7
Q

What is Broaching?

A

The process of removing metal wth a tool that has teeth aranged in a row that get successively higher than the previous tooth. It is used to create inside “square” corners. (basically like drilling a hole but it’s square so you can’t use spinning motions)

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8
Q

What are the two types of broaching? How are they different?

A

Linear: only has teeth on one side of the tool, looks kind of like a key

Rotary: Has teeth on all or multiple surfaces of the tool.

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9
Q

What are the types of chips caused by material removal?

A
  • discontinuous chips
  • continuous chips
  • continuous with built up edge (BUE)
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10
Q

What indications can be taken from a discontinuous chip?

A
  • brittle work material
  • small rake angle
  • coarse feeds and low speeds
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11
Q

What indications can be taken from a continuous chip?

A
  • ductile work material
  • large rake angle
  • fine feeds and high speeds
  • use of coolant and good chip flow
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12
Q

What indications can be taken from a continuous chip with BUE?

A
  • high friction between the work and tool cause high temperatures that will occasionally weld the chip to the tool. This will break free, but the effect is a rough surface on the work piece.
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13
Q

How are shear plane angle and shear plane relevant to the forces involved in cutting?

A

Higher shear angle means a smaller shear plane which leads to:

  • lower shear force
  • lower cutting forces
  • lower power
  • lower temperature
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14
Q

Theoretically, what is the difference between a positive and negative rake angle?

A

Positive essentially means that the material is being pushed off the work piece.
Negative means the material is being pulled off, in a scraping motion.

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15
Q

In terms of chip formation, what is r?

A

chip thickness ratio

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16
Q

In terms of chip formation, what is to?

A

Thickness before chip

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17
Q

In terms of chip formation, what is tc?

A

thickness after chip

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18
Q

In terms of chip formation, what is ls?

A

????????

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19
Q

In terms of chip formation, what is alpha?

A

rake angle

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20
Q

In terms of chip formation, what is phi?

A

shear angle

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21
Q

In terms of chip formation, what is gamma?

A

shear strain

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22
Q

In terms of chip formation, what is Fc?

A

cutting force

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23
Q

In terms of chip formation, what is Ft?

A

tangential force (sometimes call thrust force)

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24
Q

In terms of chip formation, what is R?

A

Resultant force

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25
Q

In terms of chip formation, what is F?

A

Friction force ( between tool and chip)

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26
Q

In terms of chip formation, what is N?

A

Normal force (between tool and chip)

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27
Q

In terms of chip formation, what is Fs?

A

Shear force

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28
Q

In terms of chip formation, what is Fn?

A

Normal force to shear plane

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29
Q

What strategy can we use to calculate forces involved in cutting?

A

Merchant’s circle diagram

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30
Q

In terms of chip formation, what is Beta?

A

friction angle

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31
Q

In terms of chip formation, what is As?

A

Area of the shear plane.

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32
Q

In terms of chip formation, what is Tau?

A

Shear stress which is equal to shear strength, S.

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33
Q

Since we know that increasing the shear plane angle decreases force, power, and temperature, what are some methods to increase the shear angle?

A
  • increase the rake angle

- reduce the friction angle and/or the coefficient of friction.

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34
Q

In terms of chip formation, what is w?

A

width of cutting

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35
Q

What are some properties of cutting tools?

A
  1. Hardness
  2. Toughness
  3. Resistance to abrasion and wear
  4. Strength to resist bulk deformation
  5. adequate thermal properties
  6. Correct geometry
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36
Q

What is the relation between hardness and toughness?

A

Materials with higher hardness have lower toughness.

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37
Q

What is toughness?

A

The ability of a material to absorb energy and plastically deform without fracture.

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38
Q

What is hardness?

A

The ability of a material surface to withstand local deformation.

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39
Q

Whats is the basic principle in regards to tool material hardness?

A

You need a material with a higher hardness than your stock material

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40
Q

What may cause tool failure?

A
  • Fracture failure: forces on the tool exceed the tool strength
  • Temperature failure: high temperatures lead to plastic deformation or premature wear.
  • Gradual wear: normal wearing process of the tool.
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41
Q

For a Tool flank wear VS Time of cutting graph, what are the three regions?

A
  • break in period
  • Steady state wear region
  • Failure region
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42
Q

What are the wear modes for a cutting tool?

A
  • Nose radius wear
  • Flank wear
  • Crater wear
  • Notch wear
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43
Q

What are the wear types for a cutting tool?

A
  • Abrasion
  • Adhesion
  • Diffusion
  • Plastic deformation
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44
Q

Abrasion is the dominant cause of what?

A

Flank wear

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45
Q

Explain adhesion. What types of wear are associated?

A

High pressure localized fusion and rupturing. Flank and notch wear.

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46
Q

Explain diffusion. What type of wear is associated?

A

Loss of hardening atoms at the too-chip boundary. Crater wear.

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47
Q

Plastic deformation contributes to what?

A

Flank wear.

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48
Q

In terms of wear, what is v?

A

cutting speed

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49
Q

In terms of wear, what is T?

A

Tool life

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50
Q

In terms of wear, what is n and C?

A

constants

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51
Q

What are some common machining tool materials?

A
  1. Plain carbon steel
  2. High speed steel
  3. Carbides
  4. Ceramics
  5. Synthetic diamonds and cubic boron nitride.
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52
Q

Plain carbon steel is usually used for what in machining?

A

Not used much anymore because it loses hardness at low temp (150 - 300 C)
Used for: taps, dies, chisels.

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53
Q

What properties make HSS a valid option for drill bits, lathe tools, and end mills?

A
  • withstand up to 600 C
  • usually have the best toughness of most materials.
  • can often be coated with titanium/cobalt to extend lifetime
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54
Q

How are carbides better than HSS?

A
  • Cutting speed is 3-5x faster than HSS.
  • withstand up to 800 C
  • can be coated to increase resistance to wear
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55
Q

What are ceramics typically used for and why?

A
  • cut 2-3x faster than carbides
  • mainly used for high speed turning of cast iron and steel
  • have poor thermal and shock resistance
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56
Q

What determines the geometry of a cutting tool?

A
  • properties of the work piece material
  • material of the cutting tool
  • type of cutting operation
  • strength of cutting edge
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57
Q

Which tools are typically used for negative rake angles?

A
  • carbide
  • diamond
  • ceramics
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58
Q

What property of a material is important for small or negative rake angles?

A

Hard/brittle!

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59
Q

What does the nose radius affect for the work piece?

A

surface finish

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60
Q

What is the function of coolant as a cutting fluid?

A
  • lubricant: reduce friction, extends tool life, reduces forces/energy consumption.
  • cools the cutting zone
  • protects new surfaces from corrosion
  • helps to remove chips for area
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61
Q

Machined parts can be classified into two categories. What are they?

A
  • Rotational: cylindrical or disk like

- Nonrotational: block like or plate like

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62
Q

What factors affects the characteristic part geometry?

A
  1. Relative Motions - generating: part geometry is determined by the feed trajectory of the cutting tool
  2. Shape of the cutting tool - forming: part geometry is created by the shape of the cutting tool
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63
Q

What methods are used for generating shape?

A
  • straight turning
  • taper turning
  • contour turning
  • slab milling (peripheral)
  • profile milling (end)
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64
Q

What methods are used for forming a shape?

A
  • form turning
  • drilling
  • broaching
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65
Q

What are some methods that combine both generating and forming?

A
  • thread cutting on a lathe

- slot milling

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66
Q

In terms of turning, what is V?

A

Linear cutting speed

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67
Q

In terms of turning, what is N?

A

rotational speed of spindle

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68
Q

In terms of turning, what is f?

A

feed

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69
Q

Does cutting force increase of decrease at higher speeds?

A

Force slightly decreases at higher cutting speeds.

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70
Q

What variations of turning can be performed on a lathe?

A
  • basic turning
  • facing
  • contour turning
  • chamfering
  • cutoff
  • threading
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71
Q

What is facing?

A

Tool is fed radially inward

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72
Q

What is chamfering?

A

cutting edge cuts an angle on the corner of the cylinder, forming a chamfer.

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73
Q

What is parting?

A

Tool is fed radially inward into rotating work at some location to cut off end part.

74
Q

What methods are used to hole the work piece in a lathe?

A
  • holding between centers
  • chuck (3 jaw or 4 jaw)
  • collet
  • face plate ( for offset or non cylindrical workparts)
75
Q

What is boring?

A

This class haha jk

Boring is turning but performed on the inside diameter of an existing hole

76
Q

What is the difference between drilling and boring?

A

Boring can only enlarge an existing hole.

77
Q

Why is peck drilling commonplace?

A

improves chip evacuation

78
Q

Drill bits have 3 common point angles; 118, 60-90, and 135. What are each used for?

A

118: general drilling, soft steel, most metals.

60-90: low helix angle, non-ferrous materials.

135: hard materials, shorter cutting edge means lower friction.

79
Q

What is reaming?

A

Reaming slightly enlarges a hole, which provides and better tolerance on diameter and improves surface finish.

80
Q

What is tapping?

A

Makes internal screw threads on an existing hole

81
Q

What is milling?

A

a machining operation in which work is fed past a rotating cutter with multiple cutting edges resulting in a planar surface.

82
Q

What is peripheral milling?

A

the cutter axis is parallel to the surface being machined and cutting occurs only on the outside of the cutter.

83
Q

What is face/end milling?

A

the cutter axis is perpendicular to surface being machined and cutting occurs on the outside and end of the cutter.

84
Q

What is slotting?

A

when the width of the cutter is less than the width of the workpiece, therefore a slot is created in the workpiece.

85
Q

What is form milling?

A

the cutter has a specific form.

86
Q

What is slot, partial, and end milling in terms of face milling?

A

The cutter diameter is less than work width.

87
Q

What is profile milling?

A

The cutter moves along the outside of the part to create a flat surface.

88
Q

What type of milling would be used to create shallow pockets?

A

End milling

89
Q

What type of milling would be used to create a three dimensional surface?

A

Surface contouring

90
Q

What is the “golden rule” in milling?

A

Thick to thin

91
Q

Why is up milling occasionally preferable to down?

A

less shock to cutter, less vibration

92
Q

While up milling is more conventional, why is down milling sometimes better?

A
  • chip is thickest at the start
  • surface finish is better on brittle materials
  • but this results in more shock to the cutter.
93
Q

What are some disadvantages of conventional milling?

A
  • does not meet golden rule
  • heat diffuses into the work and causes hardening
  • more difficult to hold work in place
  • chips are carried upward messing up the finish
94
Q

When is conventional milling recommended over climb milling?

A

a) the machine is older and backlash is a concern

b) when milling castings or forgings or when the part is case hardened.

95
Q

What is the difference between shaping and planing?

A

shaping - the tool moves

planing - the work moves

96
Q

What tool material is typically used for shaping and planing?

A

HSS

97
Q

What are some economic and product design considerations in machining?

A
  • machinability
  • tolerances and surface finish
  • selection of cutting conditions
  • machining economics
98
Q

What is machinability dependent on?

A
  • work material
  • type of machining operation
  • tooling
  • cutting conditions
99
Q

How do you compare machinability?

A

Compare the machinability rating (MR) of the best material to that of the base material (1.00)

100
Q

Name some methods of machinability testing.

A
  • tool life
  • tool wear
  • cutting force
  • power required
  • cutting temp
  • MRR
101
Q

How does hardness of work affect machinability?

A

high hardness means abrasive wear increases so tool life is reduced and so is machinability.

102
Q

How does strength of work affect machinability?

A

high strength means higher cutting forces, specific energy, and cutting temperature.

103
Q

How does ductility of work affect machinability?

A

high ductility means tearing of metal as chip is formed causing poor surface finish.

104
Q

What factors relate to surface roughness in machining?

A
  • geometric factors of the tool
  • work material factors
  • vibration and machine tool factors
105
Q

What End Cutting Edge Angle (ECEA) is more favourable in regards to surface roughness? 0 or 30?

A

0 will provide a smoother finish.

106
Q

In terms of surface roughness, what is Ri?

A

theoretical arithmetic average surface roughness

107
Q

In terms of surface roughness, what is f?

A

feed

108
Q

In terms of surface roughness, what is NR?

A

nose radius

109
Q

In terms of surface roughness, what is Ra?

A

actual surface roughness

110
Q

There are typically two alternatives for machining economics. What are they?

A
  1. maximum product rate

2. Minimum unit cost

111
Q

If your goal is to achieve a maximum production rate what actions should you take?

A

minimize cutting time per unit

112
Q

In terms of production cycle time, what is Th, Tm, Tt, and Tc, and np, respectively?

A 
Th: Part handling time per part
Tm: machining time per part
Tt: tool change time per part
Tc: production cycle time per piece
np: # of pieces cut in one tool life
113
Q

What are Co and Ct?

A

Co: cost rate for operator and/or machining
Ct: cost per cutting edge

114
Q

How are disposable inserts favourable over regrindable tools?

A

Lower tool change time

115
Q

What are the factors on which the selection of feed in a machining operation should be based?

A
  • type of tooling
  • roughing or finished
  • surface requirements
  • cutting forces
116
Q

Name 6 metal forming operations.

A
  • machining
  • casting
  • rolling
  • extrusion
  • forging
  • stamping
117
Q

What is casting?

A

Taking a liquid or highly plastic work material and creating a part by solidifying the material in a mold.

118
Q

What are the 5 steps involved in casting?

A
  1. Make the mold
  2. Melt the metal
  3. Pour into mold
  4. Let freeze
  5. Remove the mold
119
Q

What are the advantages of casting?

A
  • complex part geometries (external and internal shapes)
  • near net shape
  • well suited to mass production
120
Q

What are the diasadvantages of casting?

A
  1. Limitations on mechanical properties
  2. Poor dimensional accuracy and surface finish
  3. safety hazards
  4. environmental problems
121
Q

What are the types of metal casting?

A
  • expendable mold
  • permanent mold
  • continuous mold
122
Q

Sand casting:

A
  • relatively slow cooling
  • course microstructure
  • inferior mechanical properties
123
Q

Die casting:

A
  • relatively fast cooling
  • refined microstructure
  • improved mechanical properties
  • uses force and pressure
124
Q

Draw the cooling curve for a pure metal:

A 
\_\_\_\_
         .
           .
             .
                 .\_\_\_\_\_\_\_\_
                                    .
                                       .
                                          .
                                             .
125
Q

Draw the cooling curve for an alloy:

A

Same as pure metal but the flat part in the middle is angle downward.

126
Q

In terms of casting, what is Tm, Tp, H, Hf?

A

Tm: Melting temp
Tp: Pouring temp
H: energy required to melt
Hf: latent heat of fusion

127
Q

In terms of casting, what is Tst?

A

Total solidification time

128
Q

In terms of casting, what is V?

A

Volume of casting

129
Q

In terms of casting, what is A?

A

Surface area of casting

130
Q

In terms of casting, what is Cm?

A

mold constant

131
Q

What does the mold constant, Cm, depend on?

A
  • mold material
  • thermal properties of casting metal
  • pouring temp relative to melting point.
132
Q

What does the volume to surface area ratio tell us about casting?

A

higher ratio = longer cooling time

133
Q

Why must the riser have a high volume to surface area ratio than the casting?

A

The riser must solidify after the casting so that the molten metal can be fed to the main cavity.

134
Q

What is the difference between fast and slow cooling rates

A

slow- results in coarse dentritic structures with large spacing between them

fast- results in fine dentritic structure

135
Q

How do dentrites affect mechanical properties?

A

as the grain and structure size decreases:

  • strength increases
  • high temp ductility increases
  • microporosity decreases
136
Q

What is SDAS?

A

Secondary Dentrite Arm Spacing

137
Q

In terms of SDAS, what is CR?

A

Cooling rate

138
Q

Investment casting:

A
  • one of the oldest

- allow the production of components with accuracy, repeatability, versatility, and integrity

139
Q

Permanent Mold:

A
  • reusable mold usually made of metal

- uses gravity to fill the mold

140
Q

In continuous casting there are 3 cooling system, what are they?

A
  1. primary: in mold
  2. secondary: between rollers
  3. Tertiary: air
141
Q

What are some advantages to high pressure die casting (HPDC)?

A

The very fast filling of the mold allows for extremely thin-walled, shell-like structures.

142
Q

How is squeeze casting different from HPDC?

A

mold filling is done rather slowly and in a vertical movement, therefore the die has significantly less gas defects but the minimum wall thickness is slightly higher than HPDC.

143
Q

What are the advantages and disadvantages of expendable molds?

A

+ more intricate geometries are possible
+ typically lower level of automation
- higher production cost

144
Q

What are the advantages and disadvantages of permanent molds?

A
  • fixed basic geometries
    + lower production cost
  • higher level of automation
    + more economic for mass production
145
Q

What are the pros and cons of continuous casting?

A

+ highly advanced
+ effective process and quality assurance control
+ mass production of specialty Fe alloys

  • economically viable in mass production only
  • requires strict control over center line segregation and shrinkage porosity
146
Q

In terms of casting, what is Cl?

A

Weight specific heat of the liquid metal

147
Q

In terms of casting, what is To?

A

starting temp

148
Q

In terms of casting, what is Cs?

A

weight specific heat for the solid metal

149
Q

What are important factors to consider in order to achieve a successful pour of molten metal?

A
  • pouring temp
  • pouring rate
  • turbulence
  • surface tension
150
Q

What is shrinkage?

A

volume is lost during that transition from liquid to solid (internal)

151
Q

What is contraction?

A

volume reduction during cooling of the solid metal (external)

152
Q

What are some possible casting defects?

A
  • misrun: molten metal does not completly fill mold
  • cold shut: there is an unfilled cavity at the core
  • cold shots: there are smaller bubbles of air throughout the mold
  • shrinkage cavity: the interior core experiences shrinkage.
  • microporosity:
  • hot tear: crack
153
Q

What is metal forming?

A

A manufacturing process in which plastic deformation is used to change the shape of metal workpieces

154
Q

What are desirable material properties in metal forming?

A
  • low yield strength

- high ductility

155
Q

What are some examples of bulk deformation?

A
  • rolling
  • forging
  • extrusion
  • wire and bar drawing
156
Q

What are some examples of sheet metalworking?

A
  • bending
  • deep drawing
  • cutting
157
Q

What is rolling?

A

Rolling a material between rollers to flaten, like a pasta maker

158
Q

What is forging?

A

Pressing the material between a die to change the shape

159
Q

What is extrusion?

A

Applying a force to the back of a material to push it through a die.

160
Q

What is drawing?

A

Pulling a material through a die.

161
Q

When sheet metalworking, what is the part called and what are the tools used?

A 
Part = stampings
Tool = punch and die
162
Q

What is the difference between a punch and a die?

A 
punch = the tool applying force, fits into die
Die = the receiving tool that shapes the work.
163
Q

What is shearing of sheet metal?

A

applying a force on one side of the sheet metal to essentially tear into two pieces

164
Q

What happens to strength during deformation?

A

Typically strength will increase as a consequence of strain hardening

165
Q

In terms of sheet metal working, what is Yf?

A

Flow stress: instantaneous value of stress required to continue deforming the material

166
Q

How does flow stress relate to yield strength and tensile strength?

A

Flow stress is the intermediate value between the two.

167
Q

In terms of sheet metal working, what is Yf bar?

A

average flow stress, determined by integrating the flow curve

168
Q

What happening to the strength (K) and strain hardening exponent (n) at higher temperatures?

A

both are reduced

169
Q

What are the three temperature ranges in metal forming?

A
  • cold
  • warm
  • hot
170
Q

Cold Working:

A
  • performed at or just above room temp.

- minimum or no machining required

171
Q

What are the advantages of cold forming?

A
  1. dimensional accuracy
  2. surface finish
  3. strain hardening
  4. no heating
172
Q

What are the disadvantages of cold forming?

A
  1. higher forces
  2. clean surfaces required
  3. ductility and strain hardening limit formability
  4. residual stress
173
Q

Warm working:

A
  • performed above room temp but below recrystallization temp
174
Q

What are the advantages of warm forming?

A
  1. lower forces

2. more intricate geometries

175
Q

Hot working:

A
  • performed above recrystallization temp = 0.5Tm
176
Q

What is Recrystallization?

A

the process in which deformed grains of the crystal structure are replaced by a new set of stress-free grains that nucelate and grow until all the original grain have been consumed.

177
Q

What are the advantages of hot forming?

A
  • far more plastic deformation
  • much less forces
  • n is theoretically = 0
178
Q

What phenomenon occurs during deformation, especially at elevated temperatures?

A

Strain rate sensitivity; as strain rate increases so does resistance to deformation

179
Q

Why is friction undesirable in metal forming?

A
  • metal flow is slowed
  • forces are increased
  • tool wears faster
180
Q

What types of rolling?

A
  • flat rolling: reduce thickness

- shape rolling: makes square, round, I, T cross sections

181
Q

What is draft?

A

amount of thickness reduction

182
Q

In terms of rolling, what is F?

A

Rolling force

Manufacturing Processes (1 decks)

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