When revenue falls, inventory is often the largest pool of trapped cash in a manufacturing business. How Lean tools release it safely, without starving customers or stopping lines.
In mid-2020, a manufacturer's sales fell by a quarter in two months. The finance director's spreadsheet showed something uncomfortable: the business was holding more than ten weeks of finished goods, five weeks of work in progress and a raw material stockpile built "just in case". Several million dollars of cash was sitting on shelves while the company negotiated an extension to its overdraft.
Inventory is usually the largest controllable pool of cash in a manufacturing business. In a crisis, releasing it safely can be the difference between drawing on debt and staying self-funded.
Why inventory builds up
Inventory is rarely the result of a single decision. It accumulates because of:
- Long changeovers, which push planners into large batches.
- Forecast-driven push scheduling, building stock for demand that may not come.
- Unreliable processes and suppliers, covered by safety stock.
- Minimum order quantities and price breaks.
- Nobody owning the total level of stock.
Where to start
- Segment inventory by value and movement. A simple ABC analysis by value, combined with how fast each item moves, shows where the cash is.
- Find the obsolete and slow-moving stock. Items with no movement in six to twelve months are candidates for sale, use or write-off.
- Stop overproduction first. Freeze builds of finished goods that already have excess cover.
- Review open purchase orders. Cancel, delay or reduce orders for materials not needed in the near term.
Lean tools that release cash sustainably
- Pull systems. Kanban links production and purchasing to real consumption, so stock reflects actual demand.
- Smaller batches through shorter changeovers. SMED makes small batches economic, cutting work in progress and finished goods.
- Flow. Cells and connected processes reduce the queues between departments that hold so much work in progress.
- Value stream mapping. The timeline shows exactly where inventory sits and how many days of demand it represents, as described in value stream mapping.
Avoid the traps
- Cutting stock across the board without understanding which items protect the constraint or critical customers.
- Reducing safety stock without improving the reliability that required it.
- Destroying supplier relationships with abrupt cancellations.
- Targeting inventory alone while lead times and service levels deteriorate.
Measure it in cash and days
Track inventory in dollars and in days of demand, by category. Set targets for each category and review them weekly during the crisis, then monthly. Link the reduction to cash flow forecasts so leadership can see the result.
After the crisis
The best outcome is not a one-off reduction, but a lower, more stable level of inventory built on better flow, shorter changeovers and reliable processes. The cash released in a crisis can be kept permanently if the underlying causes are fixed.
