Moving from Push to Pull: The Mistakes Teams Make and How to Avoid Them
In Lean manufacturing and service operations, a pull system produces and delivers goods or services only when a downstream process or customer signals demand. A push system produces based on schedules and forecasts, regardless of whether the downstream process is ready to receive. The shift from push to pull is at the heart of Lean transformation -- it reduces inventory, shortens lead times, and makes process problems visible rather than masking them with buffer stock.
In 2022, with supply chain volatility making it costly to carry excess inventory and with labour shortages reducing the ability to absorb overproduction through overtime, the case for pull production systems is stronger than in stable years. But many organisations attempt the push-to-pull transition and fail to realise the expected benefits because they make avoidable errors. Here are the most common ones.
Mistakes in Understanding the Concept
Mistake: Treating kanban as the whole solution. Kanban is the signal mechanism that enables a pull system -- a way of authorising and triggering production or movement. But implementing kanban cards or a kanban board does not, by itself, create a pull system. A pull system requires stable processes upstream and downstream, realistic capacity at each process step, and the discipline to produce only what the kanban authorises. Without those conditions, kanban becomes a paperwork layer on top of a push system.
Mistake: Trying to convert the entire value stream at once. A pull system should be implemented process step by process step, starting with the process step that is the most stable and the most straightforward. Attempting to convert an entire value stream simultaneously creates too many moving parts for the organisation to manage and makes it difficult to diagnose problems when they arise.
Mistake: Eliminating buffer stock before process stability is established. The purpose of a pull system is to eliminate the inventory buffers that disguise process instability. But if you eliminate buffer stock before you have established process stability at each step, you create stoppages rather than revealing problems. Stabilise processes first, then reduce buffers progressively as stability improves.
Mistakes in Implementation
Mistake: Setting kanban quantities too low at the start. Kanban quantities are calculated based on average daily demand and replenishment lead time, with a safety buffer. In a newly implemented pull system, the assumptions underlying those calculations are often incorrect. Starting with kanban quantities that are too low creates stockouts; starting slightly high and reducing over time as the system proves out is the safer approach.
Mistake: Not training the people who work in the system. A pull system relies on the people at each process step understanding and respecting the kanban signal. Frontline operators who have always worked in a push system -- and who have never been rewarded for leaving their workstation idle because there are no kanbans to fill -- need training and coaching to operate in the new system. Management commitment to the pull discipline is essential.
Mistake: Measuring performance with push-system metrics. In a push system, high utilisation is good (machines and people are kept busy). In a pull system, the right metric is flow -- the rate at which value moves through the system -- not utilisation. Continuing to measure and reward high utilisation after moving to a pull system creates pressure to overproduce, which defeats the purpose of the pull system.
XNM applies Lean transformation methodology in public-sector and capital-project environments. Reach out to XNM's strategic advisory team to discuss push-to-pull conversion and Lean operations for your organisation.