Lean production and just-in-time
AQA also says:
Spec content: Efficiency in production: lean production; just in time (JIT).
Students should be able to: consider how production might be made more efficient by the use of lean production techniques.
Lean Production
Lean production is a philosophy of manufacturing that aims to maximise value for the customer while minimising waste. Originating from the Toyota Production System in Japan, lean thinking identifies seven types of waste that add cost without adding value: overproduction, waiting time, unnecessary transport, over-processing, excess inventory, unnecessary motion, and defects.
The goal of lean production is not simply to cut costs but to identify and eliminate activities that consume resources without contributing to the final product's value in the eyes of the customer. A business that embraces lean production becomes more efficient, more responsive, and more competitive over time.
Key Principles of Lean Production
- Eliminate waste — identify all non-value-adding activities and remove or reduce them
- Continuous improvement (Kaizen) — all employees at every level are encouraged to identify small improvements to processes, materials, and working practices on an ongoing basis
- Quality at source — problems are identified and fixed at the point where they occur, rather than being detected (expensively) at the end of the production process
- Pull production — production is triggered by actual customer demand rather than pushing products into stock speculatively
Just-In-Time (JIT) Production
Just-in-time (JIT) is a lean production technique in which materials, components, and goods are ordered and delivered only when they are needed for production — no earlier. The aim is to eliminate the cost and waste of holding stock that is not immediately required.
How JIT Works
Rather than holding large warehouses of raw materials and components "just in case" they are needed, a JIT business maintains close relationships with reliable suppliers who can deliver exactly what is needed, in the exact quantity required, at the precise moment it is needed. Production is triggered by a customer order, not a production schedule designed to fill a warehouse.
Advantages of JIT
- Eliminates or dramatically reduces stockholding costs (warehousing, insurance, obsolescence)
- Frees up capital that would otherwise be tied up in unsold stock
- Reduces waste from stock that becomes damaged, obsolete, or unsaleable
- Encourages very close, collaborative supplier relationships
- Production is demand-driven — the business only makes what customers actually want
Disadvantages of JIT
- No buffer stock — any supplier delay, delivery failure, or demand surge can immediately halt production
- Requires extremely reliable suppliers with fast delivery capabilities — difficult to achieve with distant or unreliable suppliers
- Vulnerable to supply chain disruption (pandemics, natural disasters, industrial action at suppliers)
- Frequent small deliveries may cost more per unit than bulk ordering and may increase carbon footprint
- Requires highly accurate demand forecasting — unexpected demand spikes cannot be met from stock
Key Takeaways
- Lean production maximises value and minimises waste — eliminating non-value-adding activities to improve efficiency and competitiveness.
- Kaizen (continuous improvement) is a key lean principle — small, ongoing improvements from all staff at every level.
- JIT orders and receives materials only when needed — eliminating stockholding costs but requiring highly reliable suppliers.
- JIT's main risk is supply chain vulnerability — no buffer stock means any disruption immediately halts production.
- Lean and JIT together can significantly reduce costs and improve responsiveness, but require investment in supplier relationships and accurate demand forecasting.