Interviewer view · keep this screen to yourself

OEE of a machining line in India

You run the case. Read the prompt, answer questions from the notes below, and share data only when the candidate asks for it or gets stuck. Score at the end.

Case timer

00:00

Target length:

1. Read the prompt aloud

Read it slowly, then pause. Let the candidate ask questions before they structure.

A machining line in Pune is planned to run 480 minutes a shift. It stops for 48 minutes of breakdowns and changeovers. The ideal cycle time is 0.8 minutes per part. It makes 459 parts, of which 450 are good. What is its OEE, and which loss is biggest?

2. Answers to clarifying questions

This case has no scripted clarifying answers. Answer from the prompt, and say "assume what you think is reasonable" if the prompt does not cover it.

3. A model structure

Compare the candidate's structure with this one. A different split can be just as good if it is clean and fits the problem.

OEE = availability x performance x quality
- Availability = run time divided by planned time
- Performance = (parts made x ideal cycle time) divided by run time
- Quality = good parts divided by parts made

4. The working, step by step

Each step shows how a strong candidate works it out. Share a new fact from it only when the candidate asks or is stuck, and let them do the math: the result in the dark box is what they should reach.

Step 1: Availability
What a strong candidate does: Run time is 480 minus 48, which is 432 minutes.
Availability (fraction): (480 - 48) ÷ 480 = 0.9
Step 2: Performance
What a strong candidate does: 459 parts at 0.8 minutes ideal is 367.2 minutes of ideal work in 432 minutes of running.
Performance (fraction): 459 × 0.8 ÷ 432 = 0.85
Step 3: Quality
What a strong candidate does: 450 good out of 459.
Quality (fraction): 450 ÷ 459 = 0.9804
Step 4: OEE
What a strong candidate does: Multiply the three rates.
OEE (fraction): 0.9 × 0.85 × (450 ÷ 459) = 0.75

The recommendation to listen for

At the end, say: "The CEO walks in. What is your recommendation?"

OEE is 75 percent. The biggest loss is performance (85 percent: the line runs slower than it should), then availability (90 percent). Quality is already high. So the first actions are to find the causes of slow cycles and small stops, then to shorten changeovers, before spending money on a new line.

Risks a strong answer names: A wrong ideal cycle time makes performance look better or worse than it is.

Score the candidate

Score each criterion from 1 to 5. A 2 or a 4 sits between the descriptions.

This case has no exhibit. Score Exhibit reading on how the candidate used the data you gave them: did they pick out the number that matters and say what it means?

Structuring

1: No clear structure, or a memorized framework that does not fit the problem.
3: A sensible structure, but with some overlap, a gap, or no clear priority.
5: A structure built for this problem, with no overlap and no gaps, a stated hypothesis, and a clear first step.

Math

1: Frequent errors, no units, or needed heavy help to finish.
3: Right answers but slow or messy working, or one error caught late.
5: Accurate and clearly narrated, with units, a sense check, and what the number means.

Exhibit reading

1: Read the chart aloud without finding the number that matters.
3: Found the key number but gave only part of the so-what.
5: Pulled the right number quickly and said what it means for the case.

Synthesis

1: Summarized what was done, with no clear answer.
3: Gave an answer, but with weak reasons or no next step.
5: Answer first, then two or three reasons with numbers, the main risk, and next steps.

Communication

1: Hard to follow: long silences, no signposting.
3: Clear most of the time, with some rambling.
5: Calm and concise, signposted each step, and checked in with the interviewer.

Total

0 out of 25

Score all five criteria to see the band and the feedback template.