Industrial Glossary

The concept of Bottleneck is fundamental to the analysis of production and service systems. It designates the resource (a machine, a workstation, an operator, or even a validation step) whose capacity is below demand which is subjected to it. It is the constraint that dictates the rhythm of the entire system.

In-depth definition : A bottleneck is the slowest or most limited link in a process chain. It creates a bottleneck or queue (buffer stock) upstream and slows down the entire downstream production flow. According to Theory of Constraints (TOC) developed by Eliyahu Goldratt, a company's overall performance is limited by the performance of this bottleneck. Identifying and effectively managing the Bottleneck is therefore the number one priority of any’Operational Excellence and Industrial Engineering.

Negative impact on operating performance

An uncontrolled bottleneck has direct and costly repercussions on KPI of the company :

1. Throughput reduction : The neck dictates the maximum speed of the entire line. Whatever the speed of the other stages, final production cannot exceed the capacity of this constrained stage. This limits the TRS (Taux de Rendement Synthétique) plant.
2. Increase in inventories and costs (Muda) : The area upstream of the bottleneck accumulates Work-in-progress (WIP), This is because the previous stages produce faster than the bottleneck can consume. These inventories tie up capital (WCR), increase the risk of obsolescence and considerably lengthen the production cycle. Crossing time (Lead Time).
3. Non-compliance with Takt Time : The bottleneck prevents the plant from keeping pace with customer demand (Takt Time), jeopardizing the implementation of a Pull System.
4. Operational Stress : Teams upstream of the bottleneck feel under pressure to “push” production, while the bottleneck operator is under constant pressure never to stop, creating an inefficient and stressful working environment.

Methodologies for Identifying and Managing Constraints (TOC)

The SXE Consulting is based on Theory of Constraints (TOC) to manage the bottleneck in five key steps:

1. Identify the Constraint

In a complex system, the bottleneck may be mobile or concealed by stock. The industrial digital transformation (via the MY and the’IoT) has become crucial for this, providing accurate cycle time and utilization data in real time. Value stream mapping (Value Stream Mapping - VSM) can also be used to visualize stock build-ups that signal a Bottleneck.

2. Exploiting Constraint

Once identified, the golden rule is to ensure that the bottleneck never idle.

• Avoid breakdowns (reinforced preventive maintenance).
• Ensuring the supply of raw materials and Manufacturing files complete.
• Only process validated, compliant parts (reinforced upstream quality control).
• Relieve the bottleneck operator of ancillary tasks (e.g. cleaning, supply).

3. Subordinate all other resources to the Constraint

All stages that are not the bottleneck need to adjust their cadence in order to feed the spout at its exact rate, without overproducing. There's no need for the upstream station to produce more than the bottleneck can absorb. This reduces unnecessary work-in-progress inventories.

4. Raising Stress Capacity

It's only once you've optimized and exploited the constraint that you need to invest in increase capacity. Actions may include :

• Improved working methods (reduced set-up times - SMED).
• Investment in a faster machine or more efficient tool.
• Add human resources or automation.

5. Don't let inertia set in

If the bottleneck capacity is high, the stress will probably move elsewhere. The process must be restarted from the beginning (Continuous Improvement - KAIZEN) to identify the new and exploit it in turn.

The Bottleneck in Industrial Engineering

The bottleneck is the most powerful leverage point for a manufacturing company. Managing a Bottleneck not only boosts productivity, but also helps to reduce costs. lower operating costs and improve flexibility. Focusing on this point alone will produce significant and rapid results, fully justifying the intervention of an expert in Industrial Performance.