Just-in-Time (JIT): A pull-based system where items are produced only when needed, in the quantities needed, and at the time needed, effectively reducing inventory levels.
Jidoka (Autonomation): Designing equipment to automatically detect defects and stop the line, ensuring that quality is built into the process rather than inspected at the end.
Takt Time: The calculated pace of production required to meet customer demand, ensuring that the production rate is synchronized with the market.
Kanban: A visual signaling system (often using cards) used to control the flow of materials and trigger production in a pull system.
5S Framework: A workplace organization method consisting of Sort, Set in order, Shine, Standardize, and Sustain to create a clean and efficient environment.
Push vs. Pull Systems: Traditional systems 'push' products through based on forecasts, while Lean 'pulls' products based on actual customer orders to prevent overproduction.
Batch vs. Flow: Lean strives for 'one-piece flow' to minimize work-in-process, whereas mass production relies on large batches to maximize machine utilization.
| Feature | Mass Production | Lean Production |
|---|---|---|
| Primary Goal | Economies of Scale | Waste Elimination |
| Inventory | High (Safety Stock) | Low (Just-in-Time) |
| Quality | End-of-line Inspection | Built-in (Jidoka) |
| Worker Role | Specialized/Repetitive | Multi-skilled/Empowered |
| Batch Size | Large Batches | Small Batches/Single Piece |
Takt Time Calculation: Always ensure units are consistent when calculating Takt Time using the formula .
Identifying Waste: In scenario-based questions, look for 'hidden' wastes like moving items between warehouses (Transport) or double-checking work (Processing).
The 'Worst' Waste: Remember that overproduction is frequently cited as the most critical waste because it generates and conceals all other types of waste.
Sanity Check: If a Lean implementation suggests increasing inventory to 'be safe,' it is likely incorrect; Lean always trends toward inventory reduction.
Lean as Cost-Cutting: A common mistake is viewing Lean solely as a way to reduce headcount; true Lean focuses on growing capacity by removing waste, not just cutting costs.
Tool-Only Implementation: Organizations often fail by applying tools like Kanban or 5S without adopting the underlying culture of Kaizen and respect for people.
Local Optimization: Improving one station in isolation can create bottlenecks elsewhere; Lean requires a 'Value Stream' perspective to optimize the entire flow.
