Mechanical Engineer Interview Questions UK: 8 Real Questions and What Interviewers Want

Applying for a Mechanical Engineer job in the UK? Here is what you are likely to be asked. These questions come from our Mechanical Engineer question bank of 25 questions, written for UK employers at mid-level level.

Eight Mechanical Engineer interview questions, and what the interviewer is thinking

1. Talk me through how you would design a bolted joint that carries a fluctuating load.

Why they ask: Fasteners and joints are a staple of mechanical design interviews.

2. How do you approach designing a shaft that transmits power through gears and bearings?

Why they ask: They are testing core machine design fundamentals.

3. What CAD and simulation tools have you used, and how do you make sure your models and drawings are reliable?

Why they ask: They want evidence of practical tool proficiency and good design discipline.

4. What is fatigue, and how do you design against it?

Why they ask: Fatigue is one of the most common causes of mechanical failure in service.

5. How would you select a bearing, and what could cause it to fail early?

Why they ask: They want to see knowledge of a ubiquitous mechanical component.

6. A component you designed is failing in service after a few months. How would you investigate?

Why they ask: This is a classic mechanical engineering scenario that tests analytical method.

7. Tell me about a design you took from concept to production. What was your role and what did you learn?

Why they ask: They want evidence of ownership across the lifecycle.

8. What does a typical day as a mechanical engineer involve?

Why they ask: They want to see realistic understanding of the role.

A sample answer to question 1

Talk me through how you would design a bolted joint that carries a fluctuating load.

I would start by defining the loads: the maximum and minimum axial and shear forces, and any prying or bending. For a fatigue-loaded joint, the key is preload. A properly tightened bolt keeps the joint clamped, so most of the external load goes through the clamped members and the bolt only sees a small proportion of the fluctuation, which greatly improves fatigue life. I would choose bolt size and grade, usually 8.8 or 10.9, calculate the required preload at around 70 to 75 per cent of proof load, and work out the tightening torque, bearing in mind that friction scatter makes torque a poor control, so for critical joints I might specify tension control or angle-controlled tightening. I would check the stress amplitude against the fatigue limit, bearing pressure under the head, thread stripping and joint slip. I would also consider locking methods, such as prevailing torque nuts, and any need for washers or lubricant control.

Common mistake to avoid: Relying on torque alone; ignoring prying and embedding

Want the rest?

Full model answers, key points and common mistakes for all 25 questions are on the Mechanical Engineer interview questions page. The first five are free, no sign-up needed.