7.14 Material Handling Flashcards
1
Q
A
2
Q
What is the base measurement in sheet metal forming?
A
The outside dimension of a formed part
The base measurement is given on the engineering drawing or obtained from the original part.
3
Q
What does ‘leg’ refer to in the context of a formed angle?
A
The longer part of a formed angle
4
Q
Define ‘flange’ in sheet metal forming.
A
The shorter part of a formed angle, opposite to the leg
5
Q
What is meant by ‘bend allowance’ (BA)?
A
The curved section of the bend, considered as the length of the curved portion of the neutral line
6
Q
True or False: The bend radius (BR) is measured from the inside surface of the metal.
A
False
The bend radius is measured from a radius centre to the inside surface of the metal.
7
Q
What is the neutral axis in metal bending?
A
An imaginary line that has the same length after bending as before bending
8
Q
What does K-Factor represent?
A
The percentage of the material thickness where there is no stretching or compressing
9
Q
Fill in the blank: The distance the jaws of a folder must be set back from the mould line to form a bend is known as _______.
A
[setback (SB)]
10
Q
What is a ‘mould point’?
A
The point of intersection of the mould lines
11
Q
What is the Total Developed Width (TDW)?
A
The width of material measured around the bends from edge to edge
12
Q
What is the significance of the K-factor in bending operations?
A
It must be used for all bends that are smaller or larger than 90°
13
Q
How is the K-factor calculated for bends other than 90°?
A
K-factor = tangent of half the bend angle
14
Q
What must be used for marking out flat pattern developments on aircraft sheet metal?
A
Authorised soft markers and pencils
15
Q
Why should engineer’s scribers not be used for marking out flat patterns?
A
They can cause stress raisers and are not always authorised
16
Q
What is the purpose of creating a flat pattern in sheet metal forming?
A
To show how much material is required and to prevent material waste
17
Q
What factors should be considered when forming a straight line bend?
A
- Thickness of the material
- Alloy composition of the material
- Material’s temper (hardness)
18
Q
What is the minimum bend radius?
A
The smallest radius without weakening the metal
19
Q
True or False: The radius of a bend is measured on the outside of the curved material.
A
False
The radius of the bend is measured on the inside of the curved material.
20
Q
What is the effect of a radius that is too sharp during bending?
A
It can crack the material
21
Q
How is the setback (SB) calculated for a bend?
A
SB = Radius (R) + Thickness (MT)
The K-factor is multiplied by the sum of the radius and thickness to find the setback.
22
Q
What happens to the bend area after bending?
A
It becomes 10 - 15% thinner than before bending
23
Q
What is the significance of bend lines in flat pattern development?
A
They must be determined to develop a flat pattern for sheet metal forming
24
Q
What is the bend allowance in metalworking?
A
The length of material required for the bend.
25
What factors does the bend allowance rely on?
* Degree of bend
* Radius of the bend
* Thickness of the metal
* Type of material used
26
How does the radius of the bend relate to the thickness of the material?
The radius of the bend is normally proportional to the thickness of the material being bent.
27
What happens to the material when bending a piece of metal?
Material on the inside of the radius is compressed, while material on the outside is stretched.
28
What is the neutral axis in bending?
A space that is not affected by either force, occurring at approximately 0.445 times the metal thickness from the inside of the radius.
29
What is the formula to calculate the bend allowance for a 90° bend?
Circumference of the neutral line divided by 4.
30
Calculate the bend allowance for a 90° bend with a radius of 0.250 in and thickness of 0.051 in.
0.43 in (10.92 mm)
31
What is the formula for calculating bend allowance for angles other than 90°?
R = desired bend radius, MT = thickness of the metal, N = number of degrees of bend (1° to 180°).
32
What does a bend allowance chart provide?
Bend allowances for various angles, radii of bends, and material thicknesses.
33
What is the setback in metalworking?
The distance that must be accounted for when calculating the flat dimensions of a metal piece.
34
What is the formula to find the setback?
SB = setback, K = K-factor, R = inside radius of the bend, MT = material thickness.
35
How do you calculate the flat line dimension?
Flat = Mould Line Dimension (MLD) – Setback (SB).
36
What is the purpose of the bend sight line?
To ensure the bend is formed accurately within the bend allowance.
37
True or False: The upper number in each cell of a bend allowance chart is for a 90° bend.
True
38
Fill in the blank: The neutral axis occurs at a distance of approximately ______ times the metal thickness from the inside of the radius.
0.445
39
What should be done to avoid incorrect positioning during bending?
Align the sightline with the outer extremity of the radius bar before forming.
40
What must be added to the overall length of the layout pattern to ensure adequate material for the bend?
The length of the neutral axis.
41
What is the developed length in metalworking?
The total length of flat portions and bend allowances combined.
42
What is the process of shaping sheet metal called?
Forming
## Footnote
Forming involves altering the shape of the material, which can be simple or complex.
43
What are the two methods of forming by altering the shape of sheet metal?
Stretching & Shrinking
## Footnote
These methods change the contour of the material to achieve the desired shape.
44
What is the most easily formed metal used in aircraft construction?
Pure aluminium
## Footnote
The ease of forming aluminium alloys depends on their temper condition.
45
What is required for extensive forming or making complex curves in sheet metal?
Annealing
## Footnote
Annealing makes the metal easier to form and allows for smaller bend radii.
46
What is the role of a sheet metal folding machine in bending?
To make straight bends
## Footnote
When unavailable, short sections can be bent by hand using bending blocks.
47
What must be consulted to determine the minimum bend radius for sheet metal?
Structural Repair Manual (SRM)
## Footnote
It contains tables listing the smallest allowable radius for different thicknesses and tempers.
48
What is the importance of adjusting the clamping pressure when using a sheet metal folder?
To ensure the material is clamped securely
## Footnote
Proper clamping prevents slippage while bending.
49
Fill in the blank: The process of bending metal that protrudes beyond the bending block is done by tapping it lightly with a _______.
rubber or plastic mallet
50
What is the preferred method for curving an extruded or formed angle section?
Stretching
## Footnote
Stretching requires a V-block and a mallet for effective shaping.
51
What is a joggle in sheet metal working?
An offset at the intersection of a stringer or former
## Footnote
It allows clearance for another part while maintaining a smooth surface.
52
What is the general rule of thumb for calculating the allowance of a joggle?
Four times the material thickness
## Footnote
For 90° angles, a slightly greater allowance is needed due to stress.
53
What method can be used to form a joggle on a flat piece of metal?
Using a normal folding machine (cornice brake)
## Footnote
The joggle is formed by bending the metal at specified angles.
54
True or False: Excessive hammering during the stretching process can cause the metal to harden.
True
## Footnote
Excessive hammering induces stresses and strains in the metal.
55
What type of blocks are used for forming curved flanged parts?
Hardwood or metal forming blocks
## Footnote
These blocks are made in pairs and designed specifically for the part's shape.
56
What method can be used to reduce a curve that has been formed too much?
Reversing the angle strip on the V-block
## Footnote
Light blows of the hammer can help adjust the curve back to the desired shape.
57
What is the purpose of using a soft-faced mallet in the shrinking process?
To prevent buckling and damage to the metal
## Footnote
It helps in gradually working out buckles without harming the material.
58
What must be done after forming a flanged angle by shrinking?
Planishing against the form block
## Footnote
This step smooths out the flange and removes small irregularities.
59
What materials can be used to make forming blocks or dies for joggling?
Hardwood, steel, aluminium alloy
## Footnote
Each material has its specific use case depending on the frequency of use.
60
What is the procedure for forming a joggle using joggle blocks?
Place the part between the joggle blocks and squeeze in a vice
## Footnote
This process creates the necessary joggle in the material.
61
What should be done after the joggle is formed with joggle blocks?
Turn the joggle blocks over and flatten the bulge with a wooden mallet
## Footnote
This ensures that the opposite flange is smoothed out.
62
When are hardwood dies considered satisfactory for joggling?
When the die is to be used only a few times
## Footnote
Hardwood dies are less durable than steel or aluminium alloy.
63
What are the advantages of using aluminium alloy dies for joggling?
Easier to fabricate, cause less surface damage to aluminium
## Footnote
Aluminium alloy dies are preferred for producing a large number of joggles.
64
What should be done when using joggling dies for the first time?
Test them for accuracy on a test piece
## Footnote
This ensures that the dies will produce the correct dimensions.
65
What is important to maintain on the surfaces of joggle blocks?
Keep them free from dirt and filings
## Footnote
This prevents damage to the work surface during the joggling process.
66
What is an alternative method for producing a simple joggle in thin aluminium alloy?
Use a joggle plate
## Footnote
A joggle plate can simplify the joggling process for thin materials.
67
What must the thickness of the joggle plate represent?
The depth of the joggle required
## Footnote
This ensures that the joggle is formed accurately.
68
According to the four times the material thickness rule, what is the allowance for joggling?
Four times the material thickness
## Footnote
This rule helps in determining the correct dimensions for the joggle.
69
How is the metal joggled using a joggle plate?
Joggled between the slots of the joggle plate and hit with a mallet on a hard surface
## Footnote
This method creates the joggle efficiently.
70
What should you consider during a visual inspection of sheet metal work for damage?
Consider the impact from foreign objects and how far the damage extends into supporting structural members.
71
What is necessary when inspecting aircraft structures for damage?
A close inspection of all rivets, bolts, and attaching structures along the complete member for evidence of damage.
72
What must be periodically inspected in an aircraft structure?
Structural integrity.
73
Where is corrosion most likely to occur in an aircraft structure?
In areas where moisture and salt spray can accumulate, especially in corners.
74
What indicates a loose rivet during inspection?
A dark, greasy residue or deterioration of paint around the rivet head, often called a 'smoking rivet'.
75
What visual signs indicate warped or buckled wings?
Presence of parallel skin wrinkles running diagonally across the wings.
76
What must be done to aluminium alloy surfaces with a chipped protective coating?
They must be recoated to prevent the formation of corrosion.
77
What are two Non-Destructive Testing (NDT) methods used for inspecting structural members?
Eddy current and ultrasonic inspection techniques.
78
Define burnishing in the context of aircraft parts.
Polishing of one surface by sliding contact with a smooth and harder surface, usually without displacement of metal.
79
What is the definition of corrosion?
Loss of metal from the surface by chemical or electrochemical action.
80
What does a crack in metal indicate?
A physical separation of two adjacent portions of metal caused by excessive stress.
81
What is a dent?
Indentation in a metal surface produced by an object striking with force.
82
What is the result of erosion on a metal surface?
Loss of metal from the surface by mechanical action of foreign objects.
83
What does chattering refer to?
Breakdown or deterioration of metal surface by vibratory or chattering action.
84
What does a gouge indicate on a metal surface?
Indicates metal loss or displacement of material due to contact with foreign material under heavy pressure.
85
What is pitting in the context of metal surfaces?
Sharp, localized breakdown of metal surface, usually with defined edges.
86
How should riveted joints be inspected?
Examine both the shop and manufactured heads, the surrounding skin, and structural parts for deformities.
87
What should be done if rivets show head slippage?
They must be replaced.
88
What does the presence of black residue around rivets indicate?
Indicates movement (fretting), not necessarily looseness.
89
What are the acceptable conditions for rivet head cracks?
Depth < 0.32 cm, width < 0.16 cm, and confined to a specific area.
90
What is the significance of keeping drain holes clean in aircraft structures?
Prevents moisture accumulation and potential corrosion.
91
Fill in the blank: A _______ is a groove in or breakdown of a metal surface from contact with foreign material under heavy pressure.
[gouge]
92
True or False: A loose rivet will always overload adjacent rivets to the point of cracking.
False.
93
What is the primary purpose of bonding in the aerospace industry?
To form permanent joints between materials such as composites, fabrics, metals, and plastics.
94
What factors determine the type of adhesive used in bonding?
Surface texture of adherent, type of joint required, and manner of load application.
95
What are adhesives primarily made of?
Synthetic resins.
96
True or False: Most bonding is performed during the manufacturing stage.
True.
97
What should be ensured when working with adhesives and sealants?
Proper ventilation or a Local Exhaust Ventilation (LEV) system.
98
What are the advantages of bonded repairs compared to bolted repairs?
They do not add stresses to the structure by drilling fastener holes.
99
What is a disadvantage of bonded repairs?
They require special storage, handling, and curing procedures.
100
Bolted repairs are typically used on composite skins thicker than ______.
6 mm (0.125 in).
101
What type of repair is most effective for honeycomb sandwich parts?
Bonded scarf (tapered) type repair.
102
How many basic types of composite repairs are there?
Five.
103
List the types of composite repairs.
* Bolted metal or pre-cured composite patches
* Bonded metal or pre-cured composite patches
* Resin injection
* Laminating new repair plies through one surface
* Laminating new repair plies through both surfaces
104
What is the best type of permanent repair to a composite structure?
Laminating new repair plies in the damaged area.
105
What tools are best suited for cutting prepreg and dry fabrics?
Heavy-duty scissors.
106
What type of power tools are recommended for working with composite materials?
Pneumatic power tools.
107
What is a caul plate used for during the curing process?
To support the composite structure/panel.
108
What is the purpose of vacuum bagging in composite repairs?
To create a secure bond by removing air from the bag.
109
What is the role of release agents in composite repairs?
To allow the part to come off the tool or caul plate easily after curing.
110
What does a bleeder ply do in the vacuum bagging process?
Creates a path for air to escape and collects excess resin.
111
Fill in the blank: A _______ is used to seal the vacuum bag to the component and create an air-tight seal.
Vacuum bag sealing tape.
112
What is the purpose of a vacuum pump in composite repairs?
To remove air from the vacuum bag and create pressure on the plies.
113
What is the typical cure temperature range for ovens used in composite repairs?
120 °C (250 ˚F) to 175 °C (350 °F).
114
What is an autoclave used for in composite repairs?
To control pressure and heat during the curing process.
115
What type of heating methods are typically used for aircraft repairs?
* Electrical resistance heat blankets
* Infrared heat lamps
116
What is the function of thermocouples in the composite repair process?
To accurately measure temperatures.
117
What are the two types of thermocouples mentioned?
Type J and Type K.
118
What is the disadvantage of using room temperature wet lay ups?
They do not restore the strength and durability of the original structure.
119
Prepreg materials must be stored in a freezer below ______.
-18 °C (-0.4 °F).
120
What is the purpose of the backing on prepreg materials?
To prevent the prepreg from sticking together.
121
What is the maximum time allowed for storing a prepreg at low temperature called?
Storage life
## Footnote
Storage life is typically between six months to a year.
122
What is the maximum time allowed for a material to be at room temperature before it cures called?
Mechanical life
## Footnote
The handling life is shorter than the mechanical life.
123
What is the recommended time at room temperature to complete the lay-up process called?
Handling life
124
At what temperatures do prepregs typically cure?
120 °C (248 °F) and 200 °C (392 °F)
125
True or False: Prepreg materials should be stored in sealed, moisture-proof bags.
True
126
What overlap is generally recommended for prepreg repair plies?
1/2" (12.5mm)
127
What are the two lay-up methods for repairing materials?
* Use the largest ply first
* Use the smallest ply first and build up sizes
128
What is the high strength direction of a fabric called?
Warp
129
What is a warp clock used for?
To describe the direction of the fibres on a diagram or manufacturer’s sheets
130
What is the typical curing temperature range for composite materials?
120 °C ‑ 175 °C (248 °F ‑ 347 °F)
131
What is the disadvantage of a room temperature cure wet lay-up repair?
It does not fully restore the strength or durability of the original cured components.
132
What type of repair meets the strength requirements but is limited by time or flight cycles?
Temporary repair
133
What is the damage classification that restores the required strength but not the durability?
Interim repair
134
What type of repair restores both strength and durability?
Permanent repair
135
What is minor core damage in a sandwich honeycomb structure?
Damage smaller than 12 mm (0.5 in) in diameter
136
What is a potted repair?
A repair involving filling minor core damage with a recommended potting compound.
137
What must be done to remove water from the damaged area before repair?
All traces of water need to be removed from the core.
138
What tool is used to taper or step sand a uniform taper around cleaned-up damage?
Flexible disc sander
139
What must be done to the core before it can be successfully repaired?
Remove any traces of water
140
What is the purpose of vacuum bagging in the repair process?
To remove air and to pressurize the repair for curing.
141
What must be inspected after curing a repair?
The repair must be free from pits, blisters, resin-rich and resin-starved areas.
142
What type of inspection methods are used for post-repair inspection?
* Visual inspection
* Tap inspection
* Ultrasonic inspection
143
Fill in the blank: The engineer is responsible for recording the time in and out of the freezer for _______.
[mechanical life]
144
What must be done to the edges of the damaged area before applying the repair?
Taper or step sand the edges
145
What is the typical maximum properties curing temperature for composite repairs?
65 °C (149 °F)
146
What should be done if the resin system is not fully mixed?
The resin cannot cure properly.
147
True or False: Mixing large quantities of quick curing resins is recommended.
False
148
What must be kept clean for successful adhesion in bonded areas?
Bonded areas
## Footnote
Clean surfaces are crucial for the integrity of the bond.
149
What is the purpose of peel ply in composite bonding?
Ensures surface cleanliness prior to bonding
## Footnote
Peel ply creates a pristine surface when stripped away.
150
What effect do high resin peaks from peel ply weave have?
They can create cracks in the bond line
## Footnote
Light sanding can remove these peaks.
151
What temperature conditions are preferred for bonded repairs with composite materials?
Elevated temperatures
## Footnote
Higher quality bonds are produced at elevated temperatures.
152
What methods can be used to increase temperature during aircraft repairs?
Heat bonder, heat lamps, hot air, heat blankets
## Footnote
These methods help maintain the correct temperature during curing.
153
What is vacuum bagging used for in composite repairs?
To remove air from the plies of a repair layup
## Footnote
Pressure can also be applied if required.
154
What is the effect of typical aircraft fuels on cured epoxy resin?
Little to no effect
## Footnote
However, they can saturate porous core materials.
155
Which hydraulic fluids can attack cured epoxy?
Some Skydrol™ brand hydraulic fluids
## Footnote
These are primarily used in civilian aircraft.
156
Do de-icing/anti-icing fluids affect composite structures?
No known effects
## Footnote
They do not harm composite materials.
157
What can strong acids do to cured epoxy?
Attack and destroy it
## Footnote
Weaker acids do not have this effect.
158
What effect do weaker alkalis have on cured epoxies?
No attack on cured epoxies
## Footnote
However, they can attack some structural foams.
159
Which solvent is known to chemically attack cured epoxy resin?
Methylene Chloride
## Footnote
It cannot be used on composites.
160
Why can't chemical paint strippers be used on composites?
They are largely based on methylene chloride
## Footnote
This can harm composite materials.
161
What is required for aircraft to prevent arcing or fiber damage during lightning strikes?
Electrical contact between metallic and composite parts
## Footnote
This allows for dissipation of electrical energy.
162
How does lightning travel through an aluminum skin aircraft?
Flows through the skin and discharges out the static wicks
## Footnote
Composites do not conduct electricity.
163
What must be built into composite components for lightning protection?
A conductive path
## Footnote
Resins can evaporate if not protected.
164
What are some methods for electrical bonding in composite structures?
Aluminium wires, fine aluminium screens, thin aluminium foil, flame-sprayed aluminium, bonded metal pieces
## Footnote
Each method serves to help dissipate electrical charge.
165
What must be performed after repairs to composite lightning protection methods?
An electrical continuity check
## Footnote
This verifies conductivity between the repair and surrounding mesh/wires.
166
What is the primary purpose of performing inspections on composite repairs?
To ensure the repair has been correctly executed and to document the results.
## Footnote
Inspections are carried out by an engineer after vacuum bagging materials are removed, followed by a supervisor/certifier inspection.
167
What are the common conditions recognized during post-repair inspections?
* Resin dry portions of the repair (porosity)
* Resin rich areas of the repair
* Delamination
* Debonding
* Foreign object inclusion
* Evidence of overheating
* Evidence of undercure
## Footnote
Inspecting the area surrounding the repair is also necessary for debonding and overheating evidence.
168
What is required if defects are found during the inspection process?
A standard damage assessment must be carried out and component-allowable damage limits must be applied.
169
What is documented during non-destructive inspections?
Results are recorded in a written report attached to repair documentation as evidence for certification and release to service.
170
What are some commonly used non-destructive inspection (NDI) techniques for composite structures?
* Tap testing
* Visual or optical inspection
* Bond tester or resonator
* Thermography and shearography
* Holography
* Acoustic emission
* Ultrasonics
* Radiography
## Footnote
Ultrasonics and radiography are the most commonly used methods.
171
What is tap testing used for?
To quickly evaluate accessible aircraft composite or bonded surfaces for delamination or debonding.
172
What are the three commonly used tap testing methods?
* Coin tap test
* Instrumented tap test (woodpecker)
* Tap test with a light hammer
173
True or False: Tap testing can effectively detect delamination in laminate materials.
False
## Footnote
Tap testing is not recommended for laminate materials due to their rigidity.
174
What tools are commonly used to aid visual inspection?
* 10 times magnification
* Borescopes
* Mirrors
175
What does visual inspection of a laminate typically detect?
Resin starvation appearing as porosity on the surface.
176
What is shearography used for?
Rapid assessment of flaws in surfaces of composite structures.
177
How does ultrasonic inspection work?
Ultrasonic waves travel through solids and liquids, with their attenuation revealing internal defects.
178
What is the main benefit of using X-ray inspection for composite structures?
No disassembly or removal of surface coatings is required.
179
What is produced by the passage of X-rays through a test object onto film?
A radiograph.
180
What do darker regions on a radiograph represent?
More penetrable parts of the test specimen.
181
Fill in the blank: The acoustic response from a bonded part during tap testing produces a clear _______.
audible ring
182
What is the risk associated with exposure to high levels of X-rays and gamma rays?
It is hazardous and can ultimately be fatal.
183
What influences the speed of ultrasonic waves?
The density and elasticity of the medium.
