Line and Team Balancing

Identify interferences and imbalances in work cells

The Imbalance Problem

In operations where several workers work in sequence or in parallel, it is common to observe:

  • Bottlenecks: A station that holds up the others
  • Interferences: Workers waiting for each other
  • Idle time: Idle capacity in some stations
  • Overload: Other stations at the limit

💡 Why sampling?

The traditional stopwatch requires observing one worker at a time. Sampling lets you capture the state of the entire cell simultaneously, revealing interferences that time study cannot see.

Case Study: Assembly Cell

A cell of 4 operators assembling an electronic product:

A

Pre-assembly

B

Welding

C

Testing

D

Packaging

Multi-Subject Study Design

In our app, each observation captures the state of ALL stations:

Time A B C D
08:23 ✅ Working ✅ Working ⏳ Waiting B ⏳ Waiting C
08:41 ✅ Working ✅ Working ✅ Working ⏳ Waiting C
09:07 ⏳ Waiting ✅ Working ✅ Working ✅ Working

Sampling Results

% Productive per Station

A - Pre-assembly 85%
B - Welding 92%
C - Testing 78%
D - Packaging 65%

Interference Analysis

Sampling detected the reasons for the waits:

Station Working Waiting for previous process Other delays
A - Pre-assembly 85% - 15%
B - Welding 92% 5% 3%
C - Testing 78% 18% 4%
D - Packaging 65% 28% 7%

Diagnosis

The bottleneck is at station B (Welding):

  • B works at 92% (nearly saturated)
  • C waits 18% of the time for B to finish
  • D waits 28% for C's queue to advance
  • The wait "propagates" downstream

✅ Solutions identified

  1. 1. Add capacity at B: Second welder or faster equipment
  2. 2. Move tasks from B to A: Reassign part of the work to balance
  3. 3. Buffer between B and C: WIP inventory to absorb variation
  4. 4. Reassign D: While waiting, help at C

Configuration in the App

For multi-subject studies:

  1. Create a station for each position in the cell
  2. In tasks, include "Waiting for previous process" as a delay
  3. In each observation, record the state of all stations
  4. The report will show the productivity matrix per station

Key Metrics for Balancing

% Interference

Time an operator waits for another due to imbalance.

Target: <5%

Line Efficiency

Average productivity of all stations.

Target: >85%

Variance Between Stations

Difference between the most and least productive station.

Target: <10 points

Bottleneck

Station with the highest saturation % that causes waits.

Identify and mitigate

Typical Result

After implementing the improvements based on sampling:

Before

80%

Line efficiency

After

91%

+11% capacity