Mechanical Design Interview Questions and Answers

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If you have a degree or diploma in mechanical engineering. And looking for a job in the mechanical field. Then this article can help you for your interview preparation. In this article, we will discuss commonly asked interview questions and answers on manufacturing. Interview questions discussed here are from engineering curriculum. If you are aware of mechanical engineering basics, You can answer these questions.

You can also check our previous article on frequently asked technical interview questions to mechanical freshers.

What are engineering tolerance?

Engineering Tolerances are allowable variation from given dimensions. In other words, it is the total amount by which a given dimension may vary without affecting product function.

Tolerance (for hole) = Hole (MMC) – Hole (LMC)

Why Tolerance are Required? 

The production of closely mating parts, without tolerances is economically unfeasible. This will increase the rejection rate and manufacturing cost. Therefore, tolerances are used with part dimensions to facilitate manufacturer and reduce cost.

Refer this article for more details on engineering tolerance.

What is tolerance Stackup Analysis?

Tolerance Stackup analysis is a design tool used to analyse and optimize product assembly. It calculates the cumulative effects of part tolerances in an assembly.

Read this article for more details on tolerance stackup analysis.

What are the types of tolerance?
  1. Unilateral Tolerance
  2. Bilateral Tolerance
What do you understand by fit?

The term fit refers to the permissible clearances between mating parts. The clearance between mating parts determines the type of Fit. 

What are the different types of fits?
  1. Clearance Fit
  2. Interference Fit
  3. Transition Fit

What do you understand by Engineering Drawing?

Engineering drawing is a technical document used to transfer technical information and define requirements. In other words, it’s a graphical language that communicates ideas and information from one mind to another.

What is Section, Projection, Isometric & Detailed View?

  • Projection View : Projection view represents a 3 dimensional objects in 2 dimensions while looking from one side.
  • Section View: It is used to show the interior construction of a part in engineering drawing.
  • Isometric View: Isometric projection represents a 3D objects into 2D in an engineering drawings. In this three coordinate axes appear equally foreshortened and the angle between any two axes is 120 degrees.
  • Detailed View: It represents the larger view of any section of engineering drawing.
What is the symbol of 1st and 3rd angle projection?
First Angle Projection
3rd Angle Projection
Which projections are preferred for engineering drawings?

Following two types of projections are used :

What is least count and how it is calculated?

It is the smallest value measured with the measuring instrument. For example, least count for a normal scale is 1 mm whereas for vernier scale it is 0.01 mm. 

Least Count= Value of one main scale Division – Total Number of Vernier scale division

What is least count for Vernier Scale, Micrometer and normal scale?
  • Vernier Caliper Least Count = 0.01 mm (Digital) , 0.02 mm (manual)
  • Micrometer Least Count = 0.01 mm
  • Normal scale Least Count = 1 mm 
What is factor of safety and how it is calculated?

FOS describes the load carrying capacity of a system beyond the expected or actual loads. In another words, FOS represents : how much stronger the system is compared to intended load.

FOS is calculated considering design load maximum value. Value of FOS is always greater than one.

What are types of screws?

Screws can be classified based on following parameters:

Based on Screw Head

  1. Counter Sunk Screw
  2. Raised or oval head screw
  3. Pan Head Screw
  4. Flat Head Screw
  5. Flange Head Screw

Based on Screw Drive Type

  1. Sloted
  2. Phillip 
  3. Pozi Drive
  4. Torx Head
  5. Hex Socket
  6. Trangular head
  7. Security Head Socket

Based on Screw Thread Type

  1. Machine Screw
  2. Thread Forming
  3. Thread Cutting Screw
What is datum plane?

A datum is theoretical exact plane, axis or point location that GD&T or dimensional tolerances are referenced to.

What is GD&T (Geometric Dimension & Tolerance) ?

GD&T is a system for defining engineering tolerances. It helps in conveying product assembly requirements to manufacturer. 

Read this article for the basics of gd&t.


To sum up, in this article we discussed the mechanical design interview questions. These Questions are not specific to any industry. These are general questions. Interviewer can also ask questions on your industrial training and final year project. 

Got Question?  We will be happy to help.

If you think we missed Something?  You can add to this article by sending message in comment box. We will do our best to add it in this post.

Check more interview questions on mechanical design for freshers here.

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