A bottleneck is the slowest step in a process — the one that limits total throughput. Identifying bottlenecks is essential for improving flow, reducing waiting times, and increasing capacity. This page explains how to find bottlenecks using capacity analysis, utilization, queueing behavior, and real operational data, with multiple numerical examples.

1. What a Bottleneck Is

A bottleneck is the resource or step with the lowest capacity or the highest utilization. It determines the maximum throughput of the entire system.

\[ \text{System Throughput} = \text{Bottleneck Capacity} \]

2. Methods for Identifying Bottlenecks

2.1 Compare capacities

The step with the smallest capacity (units/hour) is the bottleneck.

2.2 Compare utilizations

\[ \text{Utilization} = \frac{\text{Arrival Rate}}{\text{Capacity}} \]

The step with the highest utilization is the bottleneck.

2.3 Look for the longest queues

In stable systems, the bottleneck tends to accumulate the longest waiting lines.

2.4 Look for the longest cycle times

Steps with long processing times relative to others often become bottlenecks.

2.5 Observe real flow

Where work piles up, the bottleneck is usually visible.

3. Numerical Examples

Example 1 — Manufacturing Line

Three machines with capacities:

• Machine A: 40 units/hour
• Machine B: 30 units/hour
• Machine C: 50 units/hour

Machine B is the bottleneck because it has the lowest capacity.

Example 2 — Service System

Arrival rate = 20 customers/hour.

• Server 1 capacity = 25/hour → utilization = 0.80
• Server 2 capacity = 22/hour → utilization = 0.91
• Server 3 capacity = 30/hour → utilization = 0.67

Server 2 is the bottleneck because it has the highest utilization.

Example 3 — Warehouse Picking

• Picking: 120 orders/hour
• Packing: 90 orders/hour
• Labeling: 150 orders/hour

Packing is the bottleneck because it has the smallest capacity.

4. How Bottlenecks Affect the System

• They limit throughput.
• They increase waiting times upstream.
• They cause inventory buildup before the bottleneck.
• They reduce overall efficiency.

5. How to Confirm a Bottleneck

• Check where queues consistently form.
• Measure cycle times at each step.
• Calculate utilization for each resource.
• Observe where work-in-process accumulates.

6. Common Mistakes

• Assuming the slowest step is always the bottleneck (utilization matters too).
• Ignoring variability — high variability can create temporary bottlenecks.
• Using short-term observations instead of long-run averages.