Week 2 — Process strategy and capacity
Thursday, 8 October 2026 · Heizer Ch. 7 + S7
ChapterHeizer Ch. 7 — Process strategy; S7 Capacity and constraint management · eLibrary (university network or VPN)
Morning testReadiness Test 01 · Ch. 1 (alone, then as a team)
Bonus sheetmoved to Week 3 (not written on 8 Oct) · counts toward Test 2
Group projectkick-off at 13:00 · team of 4–5 signed up on ILIAS · description
Times09:00–12:00 · 13:00–15:30
A process can only go as fast as its slowest step, and that step sets the output for everyone.
Learning goals
- Find the bottleneck — capacity of every step, the lowest one wins
- Calculate capacity — design, effective, actual; utilization and efficiency
- Tell two times apart — throughput time vs. bottleneck time
- Choose a process — volume vs. variety; crossover of two processes
- Think in chains — the weakest firm sets the deliveries
- Model and clean data with Python — a line dashboard; messy oven logs
Before Thursday
- Team: choose a team of 4–5 and sign up on ILIAS. The same team writes the team tests and does the group project.
- Test 1 (09:15): Heizer Ch. 1 only. Calculate the Chapter 1 exercises (single-factor, multifactor, change in %, with the unit next to every result; practise with the Week 1 exercises); explain the key concepts in your own words; apply them to Frito-Lay and Hard Rock Cafe. Summary: Week 1, key content.
- Read Ch. 7 and Supplement 7.
The two firms of Test 1, in five seconds each:
Bring
Laptop (Google account) · calculator · pen · phone
Thursday
Morning · 09:00–12:00Readiness Test 01 · role play: six departments · Frito-Lay and Arnold Palmer Hospital as processes · fixed vs. variable process flows
Afternoon · 13:00–15:30The bottleneck in the line widget · case: Backhaus Kaya · Colab: which process strategy is cheapest at which volume? · bonus sheet moved to Week 3
For Week 3 or at home
- Week 2 exercises → — capacity, bottleneck and process choice, training for Test 2
- Line dashboard in Colab → — the pizza line as a dashboard with sliders
- Data cleaning in Colab → — Jonas’s oven logs · LLM prompt
Downloads
After class: the role-play cards, the case, the solved notebooks.
Optional reading
- Hopp, W. J., & Spearman, M. S. (2021). The lenses of lean: Visioning the science and practice of efficiency. Journal of Operations Management, 67(5), 610–626. https://doi.org/10.1002/joom.1115
- Holweg, M., Davies, J., De Meyer, A., Lawson, B., & Schmenner, R. W. (2018). Process theory: The principles of operations management. Oxford University Press.
Key content
Download as text · quiz-me prompt · exercises
Problem
At 12:15 the Mensa queue reaches the door, yet the cashier waits half the time. The main-dish counter serves 120 guests an hour, the cashier 240, and 180 arrive: the queue grows by 60 guests an hour in front of the counter. A second cashier changes nothing.
Warm-up (role play): six departments of a bike company, each defending its own single-factor number, face a rush order of 2,000 bikes in four weeks. That is 500 bikes a week: whose capacity decides whether it fits?
Sentence of the week
A process can only go as fast as its slowest step, and that step sets the output for everyone.
Formulas in words
| Measure | In words | Unit, e.g. |
|---|---|---|
| Capacity of a step | 60 min ÷ minutes per unit × parallel workers or machines | pizzas per hour |
| Batch machine | units per load × 60 ÷ minutes per load | rolls per hour |
| Bottleneck | the step with the lowest capacity | — |
| Line capacity | capacity of the bottleneck | pizzas per hour |
| Bottleneck time | minutes per unit at the bottleneck | min per pizza |
| Throughput time | sum of all step times of one unit, no waiting | min |
| Utilization | actual output ÷ design capacity | % |
| Efficiency | actual output ÷ effective capacity | % |
| Break-even volume | fixed cost ÷ (price − variable cost per unit) | units per year |
| Crossover volume | difference in fixed cost ÷ difference in variable cost | units per year |
- Design capacity = the most in ideal conditions; effective capacity = with planned losses (set-ups, cleaning, breaks, product mix); actual output = what was really made
- People and machines: always round up
- Heizer et al. (2023), Ch. 7 Process strategy and Supplement 7 Capacity and constraint management
Student life
- Party pizza line: dough 3 min, toppings 4 min, oven 10 min for 2 pizzas, cut 2 min → capacities 20 / 15 / 12 / 30 per hour → the oven is the bottleneck, 12 pizzas per hour. One pizza needs 19 min from dough to plate; 24 pizzas take 19 + 23 × 5 = 134 min
- A second topper changes nothing. A second oven makes 24 per hour possible → the toppings become the bottleneck (15 per hour): the bottleneck moves
- Moving day: the narrow staircase, not the size of the van
Factory
- Every step of a line can be busy or idle; only the bottleneck decides the output. More people at a non-bottleneck step add cost, not output
- Process strategies by volume and variety: process focus (low volume, high variety: job shop, craft bakery), repetitive focus (modules on a line: sandwich or roll line), product focus (high volume, low variety: continuous flow), mass customization (high volume and high variety)
- Crossover chart: a process with high fixed and low variable cost wins above the crossover volume
Supply chain
A chain delivers only what its weakest firm delivers. Frames 400, assembly 500, distribution 600 bikes per week → 400 bikes per week. Expanding a firm that is not the bottleneck adds cost, not deliveries.
Typical errors
- Adding the capacities of the steps instead of taking the minimum
- Utilization and efficiency swapped: utilization divides by design, efficiency by effective capacity
- Adding people at a step that is not the bottleneck
- Forgetting parallel machines or the batch size of the oven
- Throughput time (one unit, all steps) confused with bottleneck time (time between two finished units)