O2 Power Manufacturing Engineer Interview: Rounds, Questions and Preparation

What the job involves

A Manufacturing Engineer in the EV and cleantech sector designs, optimises, and scales production lines for components like battery modules, power electronics, and solar inverters. Day to day, you work on line layout, cycle time reduction, quality control, and supplier coordination to ensure cost-effective, high-volume output. At fast-growing firms like O2 Power, you may also support new product introduction and factory digitisation.

Role and Sector Knowledge

1. 1

   What does a Manufacturing Engineer do differently in an EV battery pack line compared to a traditional automotive assembly line?

   Highlight high-voltage safety, cell handling, laser welding, and traceability requirements. Mention that battery lines need stricter cleanliness and temperature control.

2. 2

   How would you calculate the takt time for a solar inverter assembly line if the monthly demand is 5,000 units and the plant runs 20 days a month in two shifts of 8 hours?

   Show the formula: available time / demand. Convert to seconds per unit and discuss allowances for breaks and downtime.

3. 3

   What are the key differences between PPAP and APQP, and why do they matter for a Tier-1 EV supplier?

   Explain PPAP as a production part approval process and APQP as advanced product quality planning. Emphasise early supplier involvement and risk reduction.

4. 4

   Name three critical quality checks you would implement for a lithium-ion cell-to-module welding process.

   Mention weld penetration, resistance/continuity test, and visual inspection with vision systems. Also note pull tests and X-ray for sample batches.

Technical Deep Dive

1. 5

   Explain how you would use a fishbone diagram to investigate a sudden increase in cell misalignment on a battery module line.

   Walk through categories: Man, Machine, Material, Method, Measurement, Environment. Give one specific check per category, like fixture wear or incoming cell dimension variation.

2. 6

   What is line balancing, and how would you balance a 6-station assembly line where station 3 is the bottleneck with a cycle time of 90 seconds while takt time is 60 seconds?

   Define line balancing as distributing work evenly. Suggest splitting tasks, adding a parallel station, or improving station 3's method to bring it under 60 seconds.

3. 7

   How do you set up a poka-yoke for preventing wrong polarity connection in a battery pack assembly?

   Describe a physical or sensor-based mistake-proofing device, like asymmetric connectors or a vision system that checks terminal orientation before fastening.

4. 8

   What is OEE, and how would you calculate it for a laser welding station that runs 400 minutes, produces 200 parts with 5 rejects, and has a theoretical cycle time of 1.5 minutes per part?

   OEE = Availability x Performance x Quality. Show the calculation and explain that 5 rejects reduce quality rate, and any downtime reduces availability.

Practical Scenarios

1. 9

   You are asked to reduce the cycle time of a battery module assembly line by 15 percent without major capital investment. What steps would you take?

   Start with time studies, identify non-value-added activities, apply ECRS (Eliminate, Combine, Rearrange, Simplify), and involve operators for quick kaizen ideas.

2. 10

   A supplier delivers busbars with out-of-tolerance holes. The line is stopped. How do you handle this in the short term and long term?

   Short term: contain, sort, and rework if possible. Long term: issue 8D, audit supplier, update PPAP, and add incoming inspection or dual sourcing.

3. 11

   You notice that operators on the shop floor are not following the new work instruction for torque tightening. How do you address this?

   Avoid blaming; check if the instruction is practical, provide retraining, add visual aids, and use poka-yoke or torque monitoring to enforce compliance.

4. 12

   Your company wants to introduce a new EV charger model. What manufacturing considerations would you raise in the design for manufacturability (DFM) review?

   Focus on part count reduction, standard fasteners, testability, thermal management assembly, and ease of final testing. Mention early supplier involvement.

Behavioural and HR

1. 13

   Tell me about a time you worked in a team to solve a technical problem. What was your role?

   Use STAR format. Highlight your specific contribution, how you listened to others, and the measurable outcome.

2. 14

   This role may require you to spend significant time on the shop floor, sometimes in shifts. How do you feel about that?

   Show enthusiasm for hands-on work. Mention that shop floor experience builds practical knowledge and is essential for a manufacturing engineer.

3. 15

   Why do you want to work in the EV and cleantech sector, and why a fast-growing company like O2 Power?

   Connect your personal interest in sustainability to the company's growth stage. Mention that you want to build processes from scratch and grow with the company.

4. 16

   Describe a situation where you had to learn a new tool or process quickly. How did you go about it?

   Pick a concrete example from a project or internship. Emphasise self-learning, asking questions, and applying the new skill to deliver results.