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Manufacturing Process > Week 2 > Flashcards

Week 2 Flashcards

1
Q

What are Bulk Deformation Processes characterized by?

A

Significant deformations and massive shape changes.

Example: Rolling, forging, extrusion.

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2
Q

What does ‘bulk’ refer to in Bulk Deformation Processes?

A

Workparts with relatively low surface area-to-volume ratios.

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3
Q

What are the starting work shapes for Bulk Deformation Processes?

A

Cylindrical billets and rectangular bars.

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4
Q

What is the primary interest in the plastic region of the stress-strain curve in metal forming?

A

Material being plastically deformed.

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5
Q

How is a metal’s behavior expressed in the plastic region?

A

By the flow curve.

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6
Q

What does the flow curve equation represent in metal forming?

A

The relationship between true stress and true strain.

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7
Q

What does the ‘K’ represent in the flow curve equation?

A

Strength coefficient.

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8
Q

What does the ‘n’ represent in the flow curve equation?

A

Strain hardening exponent.

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9
Q

What is flow stress?

A

The instantaneous value of stress required to continue deforming the material.

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10
Q

What happens to the strength of most metals at room temperature when deformed?

A

It increases due to strain hardening.

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11
Q

How is flow stress represented in terms of yield strength and strain?

A

Yf = KY^nf

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12
Q

What are the given values for the metal’s flow curve?

A

Strength coefficient = 850 MPa, Strain-hardening exponent = 0.30.

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13
Q

What is the formula to determine flow stress at a new length?

A

Flow stress = Strength coefficient * (strain)^Strain-hardening exponent.

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14
Q

What is the flow stress at the new length if the gage length is 100 mm and the stretched length is 157 mm?

A

Calculate using the flow stress formula with the given values.

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15
Q

How can the average flow stress during deformation be calculated?

A

By integrating the flow stress over the strain range and dividing by the strain range.

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16
Q

What is the flow stress calculation based on the given solution?

A

Flow stress = 850(0.451)^0.30 = 669.4 MPa.

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17
Q

How is the average flow stress calculated?

A

Average flow stress = 850(0.451)^0.30 / 1.30 = 514.9 MPa.

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18
Q

How is the average flow stress determined?

A

By integrating the flow curve equation between zero and the final strain value defining the range of interest.

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19
Q

What does the symbol ε represent in the flow curve equation?

A

Maximum strain during the deformation process.

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20
Q

What does the symbol σ represent in the flow curve equation?

A

Average flow stress.

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21
Q

What do the flow curve constants K and n depend on?

A

Temperature.

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22
Q

How are strength and strain hardening affected at higher temperatures?

A

Both are reduced.

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23
Q

What happens to ductility at higher temperatures?

A

It is increased.

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24
Q

What are the three temperature ranges in metal forming?

A

Cold working, warm working, and hot working.

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25
Q

What is strain rate sensitivity?

A

The occurrence of strain rate sensitivity, especially at elevated temperatures, in hot working.

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26
Q

How is strain rate defined?

A

Strain rate is defined as the true strain rate, where h is the instantaneous height of the workpiece being deformed and v is the velocity of the ram or other movement of the equipment.

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27
Q

What does the variable ‘C’ represent in the equation?

A

The strength constant (similar but not equal to strength coefficient in flow curve equation).

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28
Q

What does the variable ‘m’ represent in the equation?

A

The strain-rate sensitivity exponent.

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29
Q

What does Figure 18.6 illustrate?

A

The effect of temperature on flow stress for a typical metal.

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30
Q

What does the constant ‘C’ in Eq. (18.4) represent?

A

It decreases with increasing temperature.

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31
Q

What does the slope ‘m’ of each plot indicate?

A

It increases with increasing temperature.

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32
Q

What is open-die forging?

A

It involves compressing the work between two flat dies, allowing metal to flow laterally without constraint.

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33
Q

What is impression-die forging?

A

It involves die surfaces containing a cavity or impression that is imparted to the workpart, thus constraining metal flow and creating flash.

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34
Q

What is flashless forging?

A

It involves the workpart being completely constrained in the die, and no excess flash is produced.

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35
Q

What is the purpose of an upset forging operation?

A

To form a head on a bolt or similar hardware item.

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36
Q

What are the steps involved in an upset forging cycle?

A

1) Wire stock is fed to the stop. 2) Gripping dies close on the stock and the stop is retracted. 3) Punch moves forward. 4) Bottoms to form the head.

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37
Q

What is the final height of the part after hot upset forging?

A

The final height of the part needs to be determined.

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38
Q

What is the maximum force in the hot upset forging operation?

A

The maximum force in the operation needs to be determined.

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39
Q

What is the formula for calculating volume (V) of the given shape?

A

V = πDo^2ho/4

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40
Q

What is the formula for calculating final height (hf) of the given shape?

A

hf = V/Af

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41
Q

What is the formula for calculating strain (ε) in the given context?

A

ε = ln(50/12.5)

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42
Q

What is the formula for calculating force (F) in the given scenario?

A

F = 1.64(85)(1963.5)

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43
Q

What is rolling in the context of manufacturing processes?

A

A deformation process in which work thickness is reduced by compressive forces

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44
Q

What is rolling in the context of manufacturing processes?

A

A deformation process in which work thickness is reduced by compressive forces exerted by two opposing rolls.

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45
Q

What is flat rolling used for?

A

To reduce the thickness of a rectangular cross-section.

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46
Q

What is shape rolling used for?

A

To form a square cross-section into a shape such as an I-beam.

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47
Q

Which type of rolling is most common due to the large amount of deformation required?

A

Hot rolling.

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48
Q

What does cold rolling produce?

A

Finished sheet and plate stock.

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49
Q

What is the formula for rolling analysis related to the flow stress?

A

f_o - f_t = 36 * (σ_t / σ_r)^n * K * Y

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50
Q

What does the symbol ‘f’ represent in the rolling analysis formulas?

A

Flow stress.

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51
Q

What does the symbol ‘t’ represent in the rolling analysis formulas?

A

Thickness of the material.

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52
Q

What does the symbol ‘d’ represent in the rolling analysis formulas?

A

Roll diameter.

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53
Q

What does the symbol ‘σ’ represent in the rolling analysis formulas?

A

Stress.

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54
Q

What does the symbol ‘n’ represent in the rolling analysis formulas?

A

Strain hardening exponent.

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55
Q

What does the symbol ‘K’ represent in the rolling analysis formulas?

A

Constant related to material properties.

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56
Q

What does the symbol ‘Y’ represent in the rolling analysis formulas?

A

Yield strength.

57
Q

What is the initial thickness of the plate to be reduced in the rolling mill?

A

25 mm

58
Q

What is the final thickness of the plate after the single pass in the rolling mill?

A

20 mm

59
Q

What is the width of the plate to be reduced in the rolling mill?

A

250 mm

60
Q

What is the radius of the roll in the two high rolling mill?

A

500 mm

61
Q

What is the speed of the roll in the rolling mill?

A

30 m/min

62
Q

What is the strength coefficient of the work material?

A

240 MPa

63
Q

What is the strain hardening exponent of the work material?

A

0.2

64
Q

What is the formula to determine roll force in rolling process?

A

Roll force = (0.5 * strength coefficient * width * thickness) / roll radius.

65
Q

What is the formula to determine roll torque in rolling process?

A

Roll torque = roll force * roll radius.

66
Q

What is the formula to determine power required in rolling process?

A

Power = roll torque * roll speed.

67
Q

What is the formula for true strain?

A

True strain ε = ln(25/20) = ln 1.25 = 0.223

68
Q

What is the formula for rolling force?

A

Rolling force F = 148.1(250)(50) = 1,851,829 N

69
Q

What is the formula for torque?

A

Torque T = 0.5(1,851,829)(50 x 10 -3) = 46,296 N-m

70
Q

What is the formula for power?

A

Power P = 2π(0.159)(1,851,829)(50 x 10 -3) = 92,591 N-m/s = 92,591 W

71
Q

What are the configurations of rolling mills?

A

Two-high, three-high, four-high, cluster mill, and tandem rolling mill.

72
Q

What is the configuration of a two-high rolling mill?

A

It consists of two opposing large diameter rolls.

73
Q

How does work pass through in a three-high rolling mill?

A

It passes through both directions.

74
Q

In a four-high rolling mill, what supports the smaller work rolls?

A

Backing rolls.

75
Q

What is the configuration of a cluster mill?

A

It has multiple backing rolls on smaller rolls.

76
Q

What is the sequence in a tandem rolling mill?

A

It consists of a sequence of two-high mills.

77
Q

What is a cluster mill?

A

A rolling mill with multiple backing rolls that allow even smaller roll diameters.

78
Q

What is a tandem rolling mill?

A

A series of rolling stands in sequence.

79
Q

How many mills are there in a tandem rolling mill?

A

Sequence of two-high mills.

80
Q

What is the purpose of ring rolling?

A

To reduce the wall thickness and increase the diameter of a ring.

81
Q

What are the two key stages of the ring rolling process?

A

Start and completion of the process.

82
Q

What is trimming in the context of impression-die forging?

A

It is a cutting operation to remove flash from the workpart.

83
Q

When is trimming usually done in impression-die forging?

A

While the work is still hot.

84
Q

What is included at the forging station to perform trimming?

A

A separate trimming press.

85
Q

Besides a trimming press, what are alternative methods for trimming in impression-die forging?

A

Grinding or sawing.

86
Q

What is extrusion?

A

A compression forming process in which the work metal is forced to flow through a die opening to produce a desired cross-sectional shape.

87
Q

How is the process of extrusion compared to in the description?

A

It is similar to squeezing toothpaste out of a toothpaste tube.

88
Q

What is the purpose of extrusion?

A

To produce long parts of uniform cross-sections.

89
Q

Besides a trimming press, what are alternative methods for trimming in impression-die forging?

A

Grinding or sawing.

Example: Grinding or sawing can be used as alternative methods for trimming in impression-die forging.

90
Q

What is extrusion?

A

A compression forming process in which the work metal is forced to flow through a die opening to produce a desired cross-sectional shape.

Example: Extrusion is a process where metal is forced through a die to create a specific shape.

91
Q

How is the process of extrusion compared to in the description?

A

It is similar to squeezing toothpaste out of a toothpaste tube.

Example: The extrusion process is likened to squeezing toothpaste out of a tube.

92
Q

What is the purpose of extrusion?

A

To produce long parts of uniform cross-sections.

Example: Extrusion is used to create long parts with consistent cross-sections.

93
Q

What are the two basic types of extrusion?

A

Direct extrusion and Indirect extrusion.

Example: The two main types of extrusion are direct and indirect extrusion.

94
Q

What is another name for direct extrusion?

A

Forward extrusion.

Example: Forward extrusion is another term for direct extrusion.

95
Q

What is the extra portion of the billet that remains as the ram approaches the die opening called?

A

The butt.

Example: The portion of the billet left after extrusion is known as the butt.

96
Q

How is the extra portion (butt) separated from the extruded product?

A

By cutting it just beyond the die exit.

Example: The butt is removed by cutting it beyond the die exit.

97
Q

What determines the final shape of the extruded product in direct extrusion?

A

The die opening.

Example: The final shape of an extruded product is determined by the die opening in direct extrusion.

98
Q

What are the alternative names for indirect extrusion?

A

Backward extrusion and reverse extrusion.

Example: Indirect extrusion is also known as backward or reverse extrusion.

99
Q

What are the limitations of indirect extrusion?

A

Lower rigidity of hollow ram and difficulty in supporting the extruded product as it exits the die.

Example: Indirect extrusion has limitations such as lower rigidity of the ram and challenges in supporting the extruded product.

100
Q

What is the extrusion ratio also known as?

A

Reduction ratio.

Example: The extrusion ratio is also referred to as the reduction ratio.

101
Q

How is the extrusion ratio defined?

A

Extrusion ratio (r_x) = A_o / A_f, where A_o = cross-sectional area of the starting billet and A_f = final cross-sectional area of the extruded section.

Example: The extrusion ratio is calculated by dividing the initial cross-sectional area by the final cross-sectional area.

102
Q

To which types of extrusion does the extrusion ratio apply?

A

Both direct and indirect extrusion.

Example: The extrusion ratio is applicable to both direct and indirect extrusion processes.

103
Q

What is the simplest cross-section shape for an extrusion die orifice?

A

Circular die orifice.

Example: The simplest shape for an extrusion die orifice is circular.

104
Q

How does the shape of the die orifice affect ram pressure?

A

The shape of the die orifice affects ram pressure.

Example: The shape of the die orifice has an impact on the required ram pressure.

105
Q

What happens to the pressure and force required as the cross-section of the die orifice becomes more complex?

A

Higher pressure and greater force are required.

Example: More complex die orifice shapes result in increased pressure and force requirements.

106
Q

What is the formula for extrusion analysis?

A

f_0 = f_x * A/A_r * ln(ln(ε_x))

Example: The formula for extrusion analysis involves the initial flow stress, area reduction ratio, and strain in the x-direction.

107
Q

What does the symbol ‘ε_x’ represent in the extrusion analysis formula?

A

Strain in the x-direction.

Example: ‘ε_x’ in the extrusion analysis formula signifies the strain in the x-direction.

108
Q

What is the formula for the flow stress in extrusion analysis?

A

f = n * K * (ε^p)

Example: The formula for flow stress in extrusion analysis includes the strain hardening exponent, constant, and strain.

109
Q

What does the symbol ‘n’ represent in the flow stress formula for extrusion analysis?

A

Strain hardening exponent.

Example: ‘n’ in the flow stress formula represents the strain hardening exponent.

110
Q

What is the formula for the indirect extrusion force?

A

P = F_v * (A/A_r) * K * shape factor

Example: The formula for indirect extrusion force involves the vertical force, area reduction ratio, constant, and shape factor.

111
Q

How is the change in size of work usually given in drawing?

A

By area reduction.

Example: Work size changes in drawing are typically expressed in terms of area reduction.

112
Q

What does the symbol ‘r’ represent in the area reduction formula?

A

Area reduction in drawing.

Example: ‘r’ symbolizes the area reduction in the drawing process.

113
Q

How is the original area of work represented in the area reduction formula?

A

By ‘A o’.

Example: The initial work area is denoted as ‘A o’ in the area reduction formula.

114
Q

How is the final area of work represented in the area reduction formula?

A

By ‘A f’.

Example: The final work area is represented as ‘A f’ in the area reduction formula.

115
Q

What is the main difference between bar drawing and wire drawing?

A

The stock size, with bar drawing using large diameter bar and rod stock, and wire drawing using small diameter stock.

Example: Bar drawing involves larger stock sizes compared to wire drawing.

116
Q

What is the possible range of wire sizes in wire drawing?

A

Wire sizes down to 0.03 mm (0.001 in.) are possible.

Example: Wire drawing can produce very fine wire sizes, as small as 0.03 mm.

117
Q

Are the methods, equipment, and terminology the same for bar drawing and wire drawing?

A

No, they are different.

Example: Bar drawing and wire drawing involve distinct methods, equipment, and terminology.

118
Q

What is the function of the entry region in a draw die?

A

It funnels lubricant into the die to prevent scoring of work and die.

Example: The entry region in a draw die serves to deliver lubricant and prevent damage to the workpiece and die.

119
Q

What is the purpose of the approach in a draw die?

A

It is a cone-shaped region where drawing occurs.

Example: The approach in a draw die is a conical area where the drawing process takes place.

120
Q

What does the bearing surface in a draw die determine?

A

It determines the final stock size.

Example: The bearing surface in a draw die influences the size of the final product.

121
Q

What is the back relief in a draw die?

A

It is the exit zone provided with a back relief angle of about 30 degrees.

Example: The back relief in a draw die is the exit area with a specific relief angle.

122
Q

What are the common materials used for draw die manufacturing?

A

Tool steels or cemented carbides.

Example: Draw dies are commonly made from tool steels or cemented carbides.

123
Q

What does the symbol ‘f_0’ represent in the extrusion analysis formula?

A

Initial flow stress

Example: ‘f_0’ stands for the initial flow stress in the extrusion analysis formula.

124
Q

What does the symbol ‘A/A_r’ represent in the extrusion analysis formula?

A

Area reduction ratio

Example: ‘A/A_r’ denotes the area reduction ratio in the extrusion analysis formula.

125
Q

What is the formula for strain in extrusion analysis?

A

ε_x = (ln(1 + (f_x * r)/(Y_p))) / (n)

Example: The formula for strain in extrusion analysis includes parameters like flow stress, area reduction, and strain hardening exponent.

126
Q

What does the symbol ‘ε_x’ represent in the strain formula for extrusion analysis?

A

Strain in the extruded material

Example: ‘ε_x’ signifies the strain in the material during extrusion in the strain formula.

127
Q

What is the formula for the shape factor in extrusion analysis?

A

F = (25.2 + 0.02 * C - 0.98 * C^2)

Example: The shape factor formula in extrusion analysis involves constants related to the process.

128
Q

What is the extrusion ratio?

A

Extrusion ratio = initial cross-sectional area / final cross-sectional area.

Example: The extrusion ratio is calculated by dividing the initial cross-sectional area by the final cross-sectional area.

129
Q

How is true strain (homogeneous deformation) determined in extrusion?

A

True strain (homogeneous deformation) is determined using the Johnson extrusion strain equation.

Example: True strain in extrusion is calculated using the Johnson extrusion strain equation.

130
Q

What is the formula for extrusion strain?

A

Extrusion strain = (ln(initial area / final area)) / (ln(initial length / final length)).

Example: The formula for extrusion strain involves the ratio of initial and final areas and lengths in the logarithmic form.

131
Q

How is ram pressure and force calculated at a specific length in extrusion?

A

The calculation of ram pressure and force at a specific length in extrusion involves complex formulas and considerations.

Example: The determination of ram pressure and force at a specific length in extrusion requires detailed calculations and analysis.

132
Q

What is the extrusion ratio?

A

Extrusion ratio = initial cross-sectional area / final cross-sectional area.

Example: If initial area = 10 mm^2 and final area = 2 mm^2, then extrusion ratio = 10 / 2 = 5

133
Q

How is true strain (homogeneous deformation) determined in extrusion?

A

True strain (homogeneous deformation) is determined using the Johnson extrusion strain equation.

134
Q

What is the formula for extrusion strain?

A

Extrusion strain = (ln(initial area / final area)) / (ln(initial length / final length)).

135
Q

How is ram pressure and force calculated at a specific length in extrusion?

A

Ram pressure and force are calculated using the given parameters and the extrusion process equations.

136
Q

What is the formula for calculating the area reduction in bulk deformation processes?

A

r_x = A_o / A_f = D_o^2 / D_f^2

137
Q

How is the natural logarithm of the area reduction (r_x) calculated?

A

ε = ln r_x

138
Q

What is the equation for strain hardening exponent (ε_x) in bulk deformation processes?

A

ε_x = a + b ln r_x

139
Q

How is the flow stress (f_Y) calculated in the given problem?

A

f_Y = 600(1.119)^0.25 / 1.25 = 493.7 MPa

Manufacturing Process (11 decks)

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