14 - Material Handling Flashcards
What is the purpose of a joggle in sheet metal work?
To produce a flush fit at a metal joint.
When caustic soda is applied to a metal and it turns black, what metal is indicated?
Duralumin.
What process is required to remove a scratch from a sheet of metal?
Burnishing.
When dimpling a sheet of metal, what tooling is required?
A male and female die.
Which aluminium alloy is normally used for aircraft skin manufacturing?
2024 aluminium alloy.
What is the mold point in sheet metal fabrication?
An imaginary point from which real base measurements are provided.
What are relief holes?
Holes drilled in the corner of a metal box to prevent cracking.
What is defined as the “setback” in a bend?
The distance from the mold point to the bend tangent line.
What are faying surfaces?
Surfaces that are in contact with each other.
In sheet metal bending, how should the bend radius be measured to calculate the bend allowance?
Measure to the inside of the bend radius.
When using a squeeze dimpling tool, what must be done to accommodate different material gauges?
Adjust the jaws to accommodate different material gauges.
In sheet metal bending, what does “bend radius” refer to?
The inside radius.
Why is aircraft skin joggled?
To provide smooth airflow at faying surfaces.
What does the application of zinc chromate between faying surfaces do?
Inhibits dissimilar metal (electrolytic) corrosion.
If caustic soda turns a non-ferrous metal black, what metal is it?
Duralumin.
What is used to aid marking out on ferrous metals?
Copper sulphate solution.
How is the sight line on a sheet metal flat layout (for bending in a cornice or box brake) measured?
One radius from the bend tangent line that is placed under the brake.
When copper sulphate is used on a magnesium alloy, what is the observed effervescence?
It effervesces to a black colour.
If bend allowance tables are unavailable, how can the neutral axis of a bend be determined?
By adding approximately one‑half of the stock thickness to the bend radius.
What is the formula for setback for a 90° bend?
(R + T).
When caustic soda is applied to the edge of alclad, what colour sequence appears?
White – black – white.
For marking on a light alloy, what is used and then removed after bending?
A pencil is used to mark the material, and all marks are removed after bending.
How can corrosion be inhibited when assembling metals of different potentials?
By applying zinc or barium chromate and assembling while wet.
In a mechanical drawing, what type of line is normally used to represent an edge or object not visible to the viewer?
A medium‑weight dashed line.
When a piece of metal is bent, what is the state of the metal on the outside of the bend?
In tension.
What is the sight line of a bend?
One radius from the tangent line.
What is referred to as the minimum radius of bend?
The minimum radius of bend.
What are scribers used for?
To mark guide lines on material.
What is a hole drilled at the intersection of two bends in a fabricated sheet metal component called?
A relief hole.
What does dissimilar metal diffusion bonding provide?
High strength and brittleness.
How can marking out on stainless steel be clarified?
With copper sulphate.
When drawing lines on aluminium alloy sheet prior to bending, what should be applied?
A thin coat of zinc chromate primer, ready for pencil lines.
After solution treatment of aluminium alloy, what effect does immediate refrigeration at –15°C to –20°C have?
It suspends natural ageing for a limited period.
What does diffusion bonding and superplastic forming provide?
High stiffness and high ductility.
In a composite repair lay‑up, how much should each layer extend beyond the layer below it?
1–2 inches.
To enable a composite panel to dissipate static charge, what should it be sprayed with?
Aluminium paint.
After completing a bonded honeycomb repair using the potted compound repair technique, which non‑destructive test is used to check the repair’s soundness?
Metallic ring test.
Which non‑destructive testing technique is suitable for inspecting delamination in Redux bonded light aluminium alloy structures?
Ultrasonic.
Why is an extra layer of fibreglass added to a composite repair?
To increase the strength of the repair.
How can electrostatic charges on fibreglass surfaces be reduced or removed?
By treating the surface with a special conductive paint.
Prior to aluminium alloy bonding, what surface treatment is used?
Acid etch.
How are glass reinforced panels bonded?
With special conductive paint.
Which solvents can be used to clean tools used for fibreglass repairs?
Acetone or MEK.
Why is chopped strand mat considered a good general-purpose mat?
It gives equal properties in all directions.
