Constant Work in Progress (CONWIP)

Introduction: CONWIP

Constant Work in Progress (CONWIP) is a production management approach designed to control and limit the amount of work in progress (WIP) within a process. By capping the number of items in production, CONWIP aims to maximise throughput, minimise lead times, and reduce inventory costs.

Background

Developed as an alternative to traditional push systems, CONWIP builds on Lean Manufacturing principles and applies a pull-based mechanism. While similar in spirit to Kanban, CONWIP differs in its simplicity: rather than assigning cards to each item, it uses a fixed system-wide WIP limit to regulate production flow. This approach balances demand with capacity, ensuring resources are used efficiently without overloading the system.

Key Elements / Features

• WIP Limitation: A fixed maximum number of items in progress prevents bottlenecks and overproduction.
• Pull System: New work enters production only when capacity is freed by completed work.
• Throughput Focus: By controlling WIP, throughput time decreases, leading to faster order completion.
• Flexibility: Suitable for both make-to-stock and make-to-order environments.
• Simplified Control: The fixed cap on WIP reduces complexity in planning and monitoring.

Applications / Examples

• • Manufacturing: Automotive assembly lines and electronics production where flow stability is essential.

• Custom Orders: Make-to-order settings where demand is variable but delivery speed is critical.
• Service Processes: Workflows in IT or administration that require control of simultaneous tasks.

Relevance / Impact

CONWIP supports Lean goals of waste reduction and continuous flow. Organisations adopting this system often see improvements in operational efficiency, reduced lead times, lower inventory costs, and greater responsiveness to demand changes. By preventing overload and streamlining flow, CONWIP strengthens both productivity and customer satisfaction.

See also

• Kanban
• Just-in-Time (JIT)
• Polca
• Cycle Time