Manufacturing, automobile and engineering
Larsen and Toubro Defence R&D Engineer Interview: Rounds, Questions and Preparation
For R&D Engineer roles at companies like Larsen and Toubro Defence
What the job involves
As an R&D Engineer in manufacturing, automobile, and engineering, you will design, prototype, and test new components, systems, or processes to improve performance, cost, or reliability. Day to day work involves CAD modelling, simulation (FEA/CFD), material selection, building test rigs, analysing data, and coordinating with production and quality teams. In defence engineering, you may also work on ruggedisation, compliance with military standards, and indigenisation of imported parts.
Role and Technical Knowledge
- 1
Explain the difference between strength, stiffness, and toughness. Give an example of where each matters in a defence vehicle component.
Define each property clearly. Strength resists permanent deformation, stiffness resists elastic deformation, toughness absorbs energy before fracture. Example: armour plate needs toughness, suspension spring needs stiffness, mounting bracket needs strength.
- 2
What is GD&T? Why is it critical for parts that must be interchangeable in a defence assembly?
Mention geometric dimensioning and tolerancing symbols, datums, and how it controls form, orientation, and location. Interchangeability ensures field repairs and mass production without fitting issues.
- 3
How would you select a material for a high-stress, low-weight bracket in a military vehicle? Walk through your steps.
Start with load and environment, then shortlist based on strength-to-weight ratio, fatigue, corrosion, and cost. Consider aluminium alloys, titanium, or composites, then validate with FEA and testing.
- 4
What is DFMA? Give one example of a design change that reduced part count or assembly time.
Define design for manufacturing and assembly. Example: combining two brackets into one casting, or using snap fits instead of screws. Show awareness of cost and production time.
Practical Scenarios
- 5
A prototype part fails during vibration testing. How do you investigate and fix it?
Follow a structured approach: confirm failure mode, check FEA assumptions, inspect material and manufacturing defects, then propose design changes like ribs, fillets, or material change. Mention re-testing.
- 6
You need to reduce the weight of an existing bracket by 20 percent without compromising safety. What is your approach?
Start with load path analysis, then use topology optimisation or ribbing. Consider higher strength material. Validate with FEA and physical test. Mention that safety factor must remain above required limit.
- 7
Production reports that a newly designed part has high rejection due to warping after welding. How do you solve this?
Identify heat input and fixture issues. Suggest pre-heating, balanced welding sequence, or stress-relief heat treatment. Also review material weldability and joint design. Mention design change if needed.
- 8
You are asked to indigenise an imported hydraulic manifold. What steps will you take from reverse engineering to qualification?
Cover measuring and CAD modelling, material testing, manufacturing process selection, functional testing, and validation against original specs. Mention documentation and military standard compliance.
Behavioural and Situational Questions
- 9
Tell me about a time you worked in a team to complete a technical project under a tight deadline.
Use STAR format. Highlight your specific role, how you handled pressure, and the outcome. Mention coordination and communication.
- 10
Describe a situation where your design or calculation was wrong. How did you handle it?
Show honesty and learning. Explain how you identified the error, corrected it, and what process you put in place to avoid repeat mistakes.
- 11
Why do you want to work in the defence manufacturing sector, and what do you know about our company's products?
Connect personal interest in defence or engineering to the company's work. Mention specific product lines or technologies if known. Show awareness of indigenisation and national importance.
- 12
How would you handle a situation where a senior production engineer disagrees with your design change?
Emphasise data-driven discussion, respect for experience, and willingness to test both options. Show you can disagree without being disagreeable and focus on project goals.
HR and Career Fit
- 13
Where do you see yourself in five years in an R&D role?
Show realistic growth: from design engineer to leading a small project or becoming a subject matter expert. Align with company's need for innovation and indigenisation.
- 14
Are you willing to relocate to a manufacturing plant or defence project site?
Be honest but positive. Express flexibility and eagerness to learn on the ground. Mention that hands-on experience is valuable for an R&D engineer.
- 15
How do you keep your technical skills updated outside of college?
Mention online courses, CAD practice, reading journals, or personal projects. Show self-driven learning and curiosity.
- 16
What are your salary expectations for this fresher role?
Research typical entry-level salaries for R&D engineers in this sector. Give a range or say you are open to company standards. Focus on learning and growth opportunity.
Ready to try it for real?
Take a timed test or talk through a mock interview for this role, then see your scores.
This is practice material for R&D Engineer roles, written with AI. It is not a list of questions Larsen and Toubro Defence or any other company has asked.