Manufacturing Exam 1 Yutrzenka Flashcards
1
Q
Primary industry
A
cultivate and exploit natural resources.
Ex. farming and mining
2
Q
Secondary industry
A
Uses primary industry goods
Ex. manufacturing, construction
3
Q
Tertiary industry
A
service sector
Ex. banking
4
Q
What are the 2 types of manufacturing processes
A
Processing and assembly operations
5
Q
What is a processing operation
A
transform a material to one state of completion to a more advanced state
6
Q
What are assembly operations
A
join 2 or more components to create a new entity
7
Q
Can copper be welded? Why or why not?
A
Copper cannot be welded because of heat transfer
8
Q
Can cast iron be welded? Why or why not?
A
Cast iron cannot be welded because of heat transfer
9
Q
What is cast iron composed of
A
iron and >2% carbon
10
Q
What is metal composed of
A
iron and <2% carbon
11
Q
Types of processing operations
A
- Shaping- alter geometry
- Property enhancing- improve physical without chaning shape
- Surface processing
12
Q
Types of shaping operations and descriptions
A
- Solidification- starting material is heated liquid or semi fluid
- Particulate - starting material is powder
- Deformation- starting material is ductile solid (mostly metal)
- Material removal - starting material is ductile or brittle solid
13
Q
What are property enhancing processes, what are the types?
A
Property enhacing processes do not change the shape
Heat treatment- of metals and glass, play with time and temperature.
Sintering - of powdered metals and ceramics
14
Q
What are types of surface processes?
A
Cleaning
Surface treatments- sandblasting, carburizing
Coating and thin film deposition
15
Q
What are the 2 types of assembling processes and describe them
A
Joining processes- create a permanent joint. Ex. welding, brazing, soldering
Mechanical assembly - fastening by a mechanical assembly. Ex. bolts, threaded fasteners, screws
16
Q
What is welding
A
combining 2 or more parts by heat and/or pressure
17
Q
Heat, pressure, or both
4 types of welding
A
stick- heat only
friction welding- heat and pressure
cold welding- pressure only
tick- without filler
18
Q
Faying surface
A
the part surfaces in contact or close proximity that are being joined
19
Q
2 categories of welding and describe them
A
Fusion- melting and coalescing material by means of heat, supplied by fuel gas, electricity, or high energy beams
Solid state- joining without fusion, no liquid phase in joint
- used for aluminum to steel for example
because they have different melting points
20
Q
How to prevent oxidation in welding
A
flux or shielding gas
21
Q
What is an autogenous weld
A
when no filler metal is used
22
Q
Brazing
A
- melting a filler metal distributed by capillary action
- no melting of base metal
- surfaces to be brazed must be pre-cleaned so they remove oil/dirt
- Filler metal(Tm) is greater than 450C (840F)
23
Q
Capillary action
A
- ability of liquid to flow in narrow spaces without the help of and in opposition to external forces (gravity)
- occurs when the adhesion to the walls is stronger than the cohesive forces between liquid molecules
- a narrow tube will draw a liquid column greater than a wider tube will
24
Q
Equation for capillary height
A
h = (2T) / (rhorg)
25
Base metals and filler metals for brazing
Base metals - filler metals
- aluminum - aluminum and silicon
- coppper - copper and phosorous
- steel, cast iron - copper and zinc
- stainless steel - gold and silver
26
What is brass composed of
70% copper, 30% zinc
27
Typical brazing clearances
.025 to .25mm
or
.001 to .01 in
28
what does HAZ stand for
heat affected zone
29
Use brazing and soldering over welding when
- metals have poor weldability
- dissimilar metals need to be joined
- the intense heat of welding may damage components
- geometry of joint is not suitable for welding, faying surface not accessible
30
Brazing limitations
- joint strength is lower than welded joint
- joint strength is lower than base metal
- higher service temp may weaken a brazed joint
- color of brazing metal may not match color of base metal
31
Characteristics of good flux
- low melting temp
- low viscosity so it can be displaced by filler metal
- protects joint until solidification of filler metal
- easy to remove after brazing
32
Heating methods for brazing
torch
furnace
resistance- heated by electrical resistance in parts
dip- molten salt bath (flux)
33
Applications of brazing
Automotive, electrical, jewelry, plumbing
34
How is soldering different from brazing?
```
Application and temp
Filler metal(Tm) with <450C (840F) is distributed by capillary action
```
35
Typical clearances for soldering
.075 to .125mm
| .003 to .005 inches
36
Soldering advantages
- less energy than brazing or welding
- variety of heating methods
- easy repair
- good electrical and thermal conductivity
37
Soldering disadvantages
- low joint strength
| - joint weakens or melts at elevated temps
38
Solder materials
alloys of tin and lead
- lead is poisonous
- tin- chemically active at soldering temps and promotes wetting temps
39
Function of soldering fluxes
- be molten at soldering temperature
- remove oxide films and tarnish from base part surfaces
- prevent oxidation during heating
- promote wetting of faying surfaces
40
What is usually done when soldering sheet metal joints
sheets are bent and interlocked before soldering to increase joint strength
41
Thermit welding
mixture of aluminum powder and iron oxide that produces an exothermic reaction when ignited
42
Thermit reaction
8Al + 3Fe3O4 into 9Fe + 4Al2O3 + heat
43
What is the process of thermit welding
1. superheated iron is contained in a crucible located above the joint to be welded
2. Crucible is tapped
3.
44
Arc welding definition
fusion welding process in which joining of metals is achieved by the heat from an electrical arc between an electrode and the work
45
Temperature in arc welding
10,000F (5500C), can melt any metal
46
Most arc welding processes add ________ to increase volume and strength
filler metal
47
What is arc welding called without filler metal
autogenous welding
48
Electric arc
- discharge of electric current across a gap in a circuit
| - it is stabilized by an ionized column of gas(plasma) through which current flows
49
Problems with manual welding
weld quality and productivity
50
Arc time
time arc is on divided by hours worked
| - time is wasted setting up/cleaning
51
What are a typical manual and machine arc welding time
manual 20%
| machine 50%
52
2 types of arc welding electrodes
Consumable- source of filler metal in arc welding
| Nonconsumable- Filler metal is added separately if used. Ex. tungsten
53
What is arc shielding
Using gas or flux to prevent weld from oxidation
54
What are typical shielding gases
Ar, He, CO2
55
What is STICK welding
- shielded metal arc welding
- uses consumable electrode consisting of a filler metal (rod or stick) coated with chemical that provide flux and shielding
56
If cooling rate of a weld is high, the brittleness is
high
57
T/F: Composition of filler metal is similar to base metal in SMAW (Stick) welding
True
58
Pros and cons of stick welding
```
Pros
- equipment is portable and low cost
- very versatile and most widely used
- application fro thickness >5mm
Cons
- Manual process
- sticks must be periodically changed
- High current may melt/burn coated prematurely
- It is seldom used for aluminum alloys, copper alloys, and titanium
```
59
Gas metal arc welding GMAW is known as
Mig (metal inert gas)
60
What type of electrode and flux is used for MIG
consumable (wire) and shielding gas
61
Types of arc shielding gases, what are they, and describe them
1. Inert gases
- argon- most widely used, produces finger like penetration
- helium- high thermal conductivity, used for hotter arc, broad but shallow penetration
2. Reactive gases
- CO2, O2, N2, H2
- CO2 is only one that can be used alone
- all can be combined with argon to get binary shielding gas blends
62
What is arc shielding (flux)? The purpose?
Substance that prevents formation of oxide. Provides a protective atmosphere to weld, stabilizes arc, reduces splattering.
63
What are tubular electrodes?
flux is contained in the core and is released as electrode is consumed
64
GMAW advantages over SMAW
```
Better arc time
better use of electrode filler
higher deposition rates
eliminates problem of slag removal
can be automated
```
65
Gas tungsten arc welding (GTAW)
1. What type of electrode
2. Common name
3. Does it use filler metal
4. What metals does it work with
1. Uses non-consumable electrode and an inert gas for arc shielding
2. TIG
3. With or without filler metal
4. Applied to most metals
66
Pros and cons of GTAW
Pros
- good weld
- no splatter
- little post weld cleaning, be no flux
Cons
- slower, more expensive
- Thickness cannot be as thick as GMAW
67
Submerged arc welding (SAW)
1. type of electrode
2. What type of flux
3. Can unused flux be recovered
1. continuous, consumable bare wire electrode
2. blanketed by granular flux
3. Unused flux is recovered
68
Applications of SAW
Weld I beams
Heavy machinery
Low carbon, low alloy and stainless steels
Must be in horizontal orientation
69
Laser welding
1. Definition
2. Flux and does it use filler metal?
3. What size welds
1. Fusion welding process in which coalescence is achieved by the energy of a highly concentrated, coherent ligh beam focused on the joint.
2. Uses shielding gas and NO filler metal.
3. Small welds
70
What does LASER stand for
Light amplification by stimulated emission of radiation
71
Laser welding advantages
1. similar and dissimilar metals can be welded
2. heating and cooling rates are much higher
3. HAZ is small
4. Clean weld joints
72
Limitations of laser welding
1. Rapid cooling rates cause cracking in high carbon steels
| 2. High equipment costs
73
Applications of laser welding
Electronics, medical equipment, transmission components in automoblies and cladding process
74
Resistance welding (RW)
1. Definition
2. How is heat generated, Heat equation
1. A group of fusion welding processes that use a combination of heat and pressure to accomplish coalescence
2. Electrical resistance. H = (I^2)RT
75
Advantages of Resistance welding
1. no filler metal
2. high production rates
3. lends itself to automation
4. lower operator skill than arc welding
5. good repeatability and reliability
76
Limitations of resistance welding
1. high initial equipment cost
| 2. limited to lap joints for most RW processes
77
Resistance spot welding
1. Definition
2. Used to join what?
3. What industries is it used in
1. Resistance welding process in which welding of faying surfaces of a lap joint is achieved at one location by opposing electrodes
2. Used to join sheet metal
3. Automobiles, metal furniture, appliances
78
What type of weld is there 10,000-15,000 welds on a car frame?
Spot welds
79
Components of resistance spot welding
1. 2 opposing electrodes
2. means of applying pressure to squeeze parts between electrodes
3. Power supply from a controlled environments
80
Resistance spot welding process
1. parts inserted between electrodes
2. electrodes on
3. current on
4. current off
5. electrodes opened
81
Resistance seam welding
Uses rotating wheel electrodes to produce a series of overlapping spot welds along lap joints
Can produce ait-tight joints
82
Resistance seam welding applications
1. gas tanks
2. automotive mufflers
3. various sheet metal containers
83
Resistance projection welding
1. Start of operation, contact between parts is at projections
2. When current is applied, weld nuggets similar to spot welding are formed at projections
84
Solid state welding (SSW)
1. Is base metal melted
2. Heat, pressure, or both
1. Do not melt base metal, joining without fusion. Ex. not liquid phase
2. Coalescene results from application fo pressure alone or a combination of heat and pressure
85
Success factors in Solid state welding (SSW)
Very clean
| in very close contact with each other to permit atomic bonding
86
Advantages of Solid state welding (SSW)
1. no HAZ, so metal around joints retains original properties
2. Many Solid state welding (SSW) processes produce welded joints that bond the entire contact interface between 2 parts rather than distinct spots of seams
3. Some Solid state welding (SSW) processes can be used to bond dissimilar metals, without concerns about relative melting points, thermal expansions, and other problems that arise in fusion welding
87
Roll welding
1. definition
2. What do you do to the interface before welding
3. similar or dissimilar metals
1. Joining w/o fusion by dies or rolls (roller bending), plastic deformation of 1 or both parts. Think interlocking fingers)
2. Pre-clean interface with wire or powerbrush
3. Applied to dissimilar metals, but works best between similar metals
88
Roll bonding
1. Must be done in multiple # of passes
| 2. Pre-heat metal sheets
89
Explosive welding
1. Commonly used to bond 2 dissimilar metals. Ex. to clad one metal on top of base metal over large areas
2. Contact pressure is applied by denoting a layer of explosives place over one of the mating member
3. Kinetic energy of the flyer plate striking the mating member produces a turbulent, wavy interface, mechanically interlocking the 2 faces
90
Explosive welding advantages and disadvantages
1. can produce a bond between 2 metals that cannot by welded by conventional means
2. large access area can be bonded
3. weld is very clean
4. large knowledge about explosives must be known
91
Friction welding (inertia)
1. Coalescence is achived by frictional heat combined with pressure
2. When properly done, no melting occurs at faying surfaces
3. Can be used for dissimilar metals
4. Amenable to automation and mass production
92
Applications of Friction welding
1. shafts/tubular parts
| 2. automotive, farm equipment
93
Limitations Friction welding
1. at least one part must be rotated
2. flash must be usually removed (extra work)
3. Upsetting reduces part length (must be considered designing)
94
Friction stir welding (FSW)
3rd body (small rotating pins) is rubbed against the 2 surfaces to be joined. The pin is plunged into the join, causing frictional heating, mixing, or stirring of the material in the joint. Most commonly used for butt joints of aluminum and titanium alloys in aerospace industry, now also in polymers and composites
95
Friction stir welding (FSW) advantages
1. superior weld strength
2. little distortion or shrinkage
3. good weld appearance
96
Friction stir welding (FSW) disadvantages
1. an exit hole is produced when tool is withdrawn
2. heavy duty clamping is required
3. milling machine needed
97
Welding defects
Cracks, cavities, solid inclusions, imperfect shape, incomplete fusion
98
Welding cracks
fracture type in weld or in base metal adjacent to weld
- serious defect because it reduces strength
- caused by embrittlement or low ductility of weld
99
Cavities
1. Porosity- small voids formed by gross trapped during solidification. Caused by inclusion of atmospheric gases, sulfur in weld, or surface contaminents
2. Shrinkage voids- cavities formed by shrinkage during solidification
100
Solid inclusions
Non-metallic material entrapped in weld metal
| Most common is slag inclusions generated during AW processes that use flux. Instead of floating
101
Incomplete fusion
weld beads has not fused throughout entire cross section
102
Inspection and testing methods
visual inspection
| non destructive
103
Visual inspection
Most widely used, human inspector
Limitations
- only surface defects are detected
- welding inspector must decide if more testing is needed
104
Nondestructive evaluation
Ultrasonic
Radiographic
Dye penetrant
Magnetic particle
105
Destructive testing
Weld is destroyed
Mechanical test- purpose is similar to tensile testing
Metallurgical tests
106
What is the reason for assembly with fasteners?
For maintenance/repair
107
Mechanical assembly involves
fasteners OR shaping/reshaping of one of the components being assembled (no fasteners required)
108
4 mechanical assembly methods
1. threaded fasteners (screws, nuts, bolts)
2. Rivets (permanent joint)
3. Interference fits
4. Other mechanical fastening methods
109
Why use mechanical assembly?
1) Ease of assembly- minimal special tools, low skill required, short time
2) Ease of disassembly- allow for maintenance
110
Describe threaded fasteners
- have external or internal threads
- in most cases, they allow for disassembly
- most important category of mechanical assembly
- screws, bolts, nuts
111
What types of holes do screws go into?
| What about bolts?
Screws- blind threaded holes
| Bolts- through holes to connect to nut
112
Setscrews
assembly functions such as fastening collars, gears, and pulleys to shafts.
1) collar to shaft
2) various setscrew geometries
113
What is the main challenge of bolted joints?
Overtightening- can cause stress that exceed strength of fastener or nut
114
Failure of overtightening can happen by
1) stripping of threads (internal or external)
| 2) excessive tensile stresses on cross-sectional area
115
What is a washer used with/purpose
Used with threaded fasteners to ensure tightness of mechanical joint. Distributes stresses, provide support for large clearance hole, seals the joint.
116
What are rivets
unthreaded head pin that joins 2 or more parts by
a) passing the pin through holes then
b) upsetting a second head in pin on the opposite side
Used for permanent joints
117
Advantages and applications of rivets
Advantages
- high production rates, simple, dependable, cheap
Applications
- aerospace
118
Types of rivets
solid, tubular, semi-tubular, bifurcated, compression
119
What type of material are rivets made of
Aluminum 2024/7075
120
Toolings/methods for rivets
- impact- 1 blow with hammer
- steady compression- riveting tools applies continuous squeezing
- combination- impact and compression
121
Interference fits
assembly methods based on mechanical interference between 2 mating parts being joined
the interference, either during assembly or after joining, holds the parts together
122
Interference fit methods
press fitting
shrink and expansion fits
snap fits
retaining rings
123
Press fitting
larger diameter pin into smaller hole
124
Reason for press fitting
locating and locking components- to augment threaded fasteners by holding parts in fixed alignment with each other
pivot points- permit rotation of one component about the other
125
Shrink fitting
external part is enlarged by heating and internal part is inserted
126
Expansion fitting
internal part is contracted by cooling and is inserted into external part
127
Uses for shrink/expansion fitting
Fit gears, pulleys, and sleeves onto shafts
128
Snap fits
joining 2 parts in which mating elements possess a temporary interference during assembly, but once assembled they interlock
- during assembly, one or both parts elastically deform to accommodate the temporary interference
- originally conceived as a method ideally suited for industrial robots, easy for humans too
129
Retaining ring, definition and use
fastener that snaps into a circumferential groove on a shaft or tube to form a shoulder
- used to locate or restrict movement of parts on a shaft
130
Integral fastener
components are deformed so they interlock as a mechanically fastened joint
131
Integral fastener methods
lanced tabs
| seaming
132
Keys to successful DFA (design of assembly)
1. design with as few parts as possible
| 2. design remaining parts so they are easy to assembly
133
Design guidelines for automated assembly
- limit the required directions of access
adding all components vertically is ideal
- use high-quality components
- minimize threaded fasteners
- use snap-fit assembly
134
Design guidelines for automated assembly
avoid parts that tangle
135
Interference fits
assembly method based on mechanical interference between two mating parts being joined
136
Conventional machining (cutting)
material removal by a sharp cutting tool
| Ex. turning, milling, drilling
137
Abrasive processes
material removal by hard, abrasive particles
| Ex. grinding, lapping
138
Non-traditional machining
mechanical, electrical, chemical, thermal, optical sources of energy
139
Relative motion is required between the tool and the work piece. This comes in the form of
```
cutting speed (primary motion)
tool feed (secondary motion)
```
140
Cons of machining
wasting material
| time consuming
141
Machining in the manufacturing sequence
Generally performed after other basic manufacturing processes such as casting, forging, and bar drawing
142
Turning
single point cutting tool removes from a rotating work piece to form a cylindrical shape
143
Through hole vs blind hole
Through hole- drill exits opposite side of work
| Blind hole- drill does not exit opposite side
144
Other operations related to turning
threading, boring (counterboring), drilling
145
Milling
- work is fed past a rotating tool with multiple cutting edges
- axis of tool rotation is perpendicular to feed direction
146
Types of milling
peripheral milling
| face milling
147
Peripehral milling
- cutter axis is parallel to surface being machined
| - cutting edges on outside periphery of cutter
148
Face milling
- cutter axis is perpendicular to surface being milled
| - cutting edges on both the end and outside periphery of the cutter
149
Roughing vs finishing cuts
usually several roughing cuts are taken, followed by one or two finishing cuts
150
4 types of chip in machining
1. discontinuous
2. continuous
3. continuous chip with built-up edge (BUE)
4. serrated
151
Discontinuous chip
- brittle work materials (Ex. cast iron)
- low cutting speeds
- large feed and depth of cut
- high tool-chip friction
152
Continuous chip
- ductile work materials
- high cutting speeds
- small feeds and depths
- sharp cutting edge
- low tool-chip friction
153
Continuous chip with BUE (built up edges
- ductile materials
- low to medium cutting speeds
- tool chip friction causes portions of chip to adhere to rake face
- BUW forms, the breaks off, cyclically
154
Serrated chip
- semi-continuous (saw-tooth appearance)
- cyclical chip forms with alternating high shear strain the low shear strain
- associated with difficult-to-machine metals at high cutting speeds (Ni-rich alloys such as stainless steel
155
Chip thickness ratio
r = t_o / t_c
```
r = chip thickness ratio
t_o = thickness of the chip prior to chip formation
t_c = chip thickness after separation
```
chip thickness after cut is always greater than before, so chip ratio is ALWAYS less than 1
156
Features of a cutting tool
Cutting edge - separates the chip from the work piece
Rake face - directs the newly formed chip away from the work piece, defined in terms of the rake angle (alpha)
Flank face - provides clearance between the tool and the new work surface, defined in terms of the relief angle
157
Determining shear plane angle
based on the geometric parameters of the model, the shear plane angle (phi) can be determined as:
tan(phi) = [rcos(alpha)] / [1 - rsin(alpha)]
```
r = chip ratio
alpha = rake angle
```
158
Forces action on chip
Friction force F and normal force N
| Shear force F_s and normal force to shear F_n
159
Coefficient of friction between tool and chip
| Friction angle beta
```
mu = F / N
mu = tan(beta)
```
160
Resultant forces acting on a chip explained in next slide
Vector addition of F and N = resultant R
Vector addition of F_s and F_n = resultant R'
Forces action on the chip must be in balance
- magnitude of R = magnitude of R'
- R' must be opposite in dirction to R
- R' must be colinear with R
161
Shear stress equation (machining)
tau = F_s / A_s
A_s = area of the shear plane
A_s = (t_o*w) / [sin(phi)]
162
Shear strain equation (machining)
gamma = tan(phi - alpha) + cot(phi)
```
gamma = shear strain
phi = sheat plane angle
alpha = rake angle of cutting tool
```
163
What forces in machining can/cannot be measured
cannnot - F, N, F_s, F_n
can -
F_c (cutting force in the direction of cutting)
F_t (thrust force perpendicular to the cutting force)
164
Equations that relate the forces that cannot be measured with the forces that can be measured are:
```
F = F_c*sin(alpha) + F_t*cos(alpha)
N = F_c*cos(alpha) - F_t*sin(alpha)
F_s = F_c*cos(phi) - F_t*sin(phi)
F_n = F_c*sin(phi) + F_t*cos(phi)
```
165
The merchant equation
Of all the possible angles at which shear deformation can occur, the work material will select a shear plane angle (phi) that __________
minimizes energy
The merchant equation (phi)
phi = 45 + alpha/2 -beta/2
166
The merchant equation (phi), what is it and what does it tell us?
phi = 45 + alpha/2 -beta/2
To increase shear plane angle
- increase the rake angle
- reduce the friction angle (or reduce the coefficient of friction)
167
Higher phi means ________ shear plane which means lower shear force, cutting forces, power, and temperature
smaller
