Mechanical Engineering Interview Questions and Answers - Sheet Metal
Q001) What is Sheetmetal? Give some examples of sheet metal components.
As the name itself suggests, sheet metal is a metal in the form of a sheet. Sheet metal is available in the sheet form as well as the coil form. The car body parts like the door, roof, hood, and fender are all sheet metal. The outer skin of an aircraft is also sheet metal. Cutlery like knives, forks, and spoons are also sheet metal components.
Q002) What is the most salient feature of sheet metal?
The most salient feature of sheet metal is its uniform thickness. In the picture, what you see is the car door made out of sheet metal. Though
you see many features on the door, the thickness is uniform throughout the part.
Q003) Why is sheet metal preferred in Aero, Auto, and many other industries?
Sheet metal is preferred in Aero, Auto, and many other industries due to its high strength-to-weight ratio.
A high strength-to-weight ratio means strong products with less weight.
Q004) What is the difference between a sheet and a plate?
The difference between the sheet and the plate is their thickness.
The thickness of the sheet is more than or equal to 0.5mm and less than or equal to 6mm.
And the thickness of the plate is more than 6mm.
Q005) What is the difference between a foil and a sheet?
The difference between the foil and the sheet is their thickness.
The thickness of the foil is less than or equal to 0.2 mm.
The thickness of the sheet is more than or equal to 0.5mm, and less than or equal to 6mm.
Q006) What's the recommended bend radius on sheet metal parts?
r ≥ t
r = Bend Radius
t = thickness of Sheet metal
The bend radius on sheet metal parts should be more than or equal to the thickness of the sheet metal.
For example, if you are bending a sheet metal of thickness 2mm, the bend radius should be a minimum of 2mm.
It is also recommended to keep the same bend radius on all bends of the sheet metal part.
If there are 2 bends in the sheet metal part, it's recommended to provide the same radius on both the bends.
Q007) What is K-Factor? Explain its significance.
When sheet metal is bent using a punch and die, the inner fibers of sheet metal experience compressive forces, and the outer fibers of the sheet metal experiences tensile forces.
In between, separating the compressive fibers and the tensile fibers is the neutral axis.
The neutral axis does not experience either compressive forces or tensile forces.
The K-Factor is a constant. The K-Factor defines the position of the neutral axis. It is mathematically calculated by the ratio of the thickness of the compressive fibers to the thickness of the sheet metal.
The K-Factor is used to calculate the developed length of sheet metal component. Usually, the value of the K-Factor is 0.4
The K-Factor depends on the sheet metal’s bend radius, thickness, material, and bending type.
Q008) What is Y-Factor?
The Y-Factor is similar to K-Factor. Y-Factor is mathematically calculated by multiplying half of k-Factor by Pi.
The Y-Factor is a more precise value to calculate the developed length.
Q009) What is the difference between the K-Factor and Y-Factor?
Both K-Factor and Y-Factor are used to Calculate the Developed Length.
The second difference is the formula. The K-Factor is calculated by dividing the thickness of the compressive fibers by the thickness of the sheet metal.
The Y-Factor is calculated by multiplying half of the k-Factor by Pi.
The third difference is precision. Y-Factor is more precise than the K-Factor.
The fourth difference is the stress consideration within the material. Y-Factor has stress consideration, whereas K-Factor has no consideration for stress.
Q010) Why is the sheet metal part's thickness shown as a reference dimension in engineering/manufacturing drawings?
The thickness of the sheet metal component is the same as the thickness of the sheet metal raw material. We are not changing or processing the thickness. Hence it is denoted as a reference dimension.
Q011) What is a flat pattern?
A flat pattern view is also called a flat view, or unfolded view, or developed view.
The unfolded view unbends all the bends and flattens the sheet metal component.
This view also generates the bend axis and bend allowance or Bend limits lines.
This unfolded view is very much essential for manufacturing sheet metal components.
Let's take an example of a c shaped sheet metal component.
The unfolded view has unbent both the bends. It also has the bend axis and bend limit lines.
We need to add all the dimensions essential for manufacturing the sheet metal component, like the dimensions to the bend axis, overall dimensions, and the bend notes.
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