Just-In-Time
JITJust-In-Time is a production strategy where items are created or delivered only as they are needed, minimizing inventory.
Just-In-Time (JIT) is an inventory management and production method. It aligns raw material orders from suppliers directly with production schedules. The goal is to receive goods only as they are needed in the production process. This reduces inventory holding costs and waste.
JIT operates on a "pull" system. Production is not based on forecasts. Instead, downstream activities signal their needs to upstream activities. For example, an assembly station running low on a component sends a signal (like a Kanban card) to the fabrication cell. The fabrication cell then produces just enough components to replenish the assembly station. This prevents the buildup of excess work-in-progress (WIP).
On the shop floor, JIT exposes inefficiencies. Without buffer stock, problems like machine downtime or quality defects immediately impact production. This forces teams to address root causes quickly. Implementing JIT frees up floor space and capital tied up in inventory. It requires reliable processes and strong supplier relationships.
Manufacturers implement JIT by creating stable production schedules and working with dependable suppliers. They may arrange for frequent, small-lot deliveries. Some automotive plants receive critical parts like seats or dashboards multiple times per day. These parts arrive in the sequence they will be installed, just minutes before they are needed on the line.
A metal fabrication shop uses JIT for its steel coils. Instead of storing a month's supply, it receives a daily delivery from a local supplier. The truck arrives each morning with the specific gauges and widths needed for that day's scheduled jobs, reducing storage needs and material handling.
What is the biggest risk of using Just-In-Time?
The primary risk is disruption to the supply chain. A late delivery from a supplier or a transportation delay can halt the entire production line because there is no buffer stock.
Is JIT the same as lean manufacturing?
No. JIT is a key part of lean manufacturing. Lean is a broader philosophy that also includes other principles like Kaizen, 5S, and waste reduction.
How does JIT affect supplier relationships?
JIT requires close partnerships with suppliers. Manufacturers and suppliers must communicate frequently and transparently. Suppliers need to be reliable and capable of delivering high-quality materials in small, frequent batches.
Can a small job shop use JIT?
Yes, though the implementation may differ. A job shop might order materials specifically for each new work order rather than stocking them. It can also organize work cells to pass parts directly to the next process, minimizing WIP.
What software helps with JIT implementation?
Manufacturing Execution Systems (MES) and Enterprise Resource Planning (ERP) systems are very helpful. They provide real-time data on production progress and inventory levels, which is needed to signal suppliers.
Lean Manufacturing
Lean manufacturing is a production method focused on maximizing customer value by systematically eliminating waste from processes.
Kanban
Kanban is a scheduling system that uses visual signals to trigger the movement of materials and work through a manufacturing process.
Inventory Turnover Ratio
The inventory turnover ratio measures how many times a company sells and replaces its inventory over a specific period.
Lead Time
Lead time is the total time elapsed from when a customer places an order to when they receive the finished product.
Work in Progress
WIPWork in Progress (WIP) is the inventory of partially finished goods waiting for completion and final inspection.