Kanban vs MRP: Complete Pull/Push System Comparison for Manufacturing

Overview

Two core production planning methodologies in manufacturing—Kanban and MRP (Material Requirements Planning)—embody fundamentally different philosophies. Kanban is a pull system based on actual demand, while MRP is a push system based on forecasts. On the shop floor, these systems provide completely different answers to the question: "When, what, and how much should we produce?"

Pull vs Push Production Principles

Pull System (Kanban)

• Downstream processes request from upstream only what's needed
• Actual consumption triggers production
• Philosophy: "Make only what's sold"

Push System (MRP)

• Production plans based on demand forecasts
• Materials and production orders pushed according to plan
• Philosophy: "Make according to plan and keep ready"

Core Comparison Table

| Aspect | Kanban (Pull) | MRP (Push) | |--------|---------------|------------| | Production Trigger | Actual consumption/use | Forecast-based planning | | Inventory Level | Minimized (Just-in-Time) | Safety stock maintained | | Application | Repetitive production, stable demand | Complex BOM, make-to-order | | Flexibility | Immediate response to demand changes | Time required for plan changes | | System Complexity | Simple, visual management | Complex calculations and IT systems | | Lead Time | Can be shortened | Relatively longer |

Kanban System Details

Operating Principle

Kanban controls production using signal cards or empty containers. For example, in an automotive assembly line, when 20 tires are consumed, the empty container returns to the supply area, signaling the need to produce another 20 units.

Advantages

• Inventory Minimization: Toyota achieved 60% inventory reduction with Kanban
• Prevents Overproduction: Produce only what's needed
• Immediate Problem Visibility: Line stops during stockouts reveal quality issues early

Disadvantages

• Risk of stockouts with high demand variability
• Difficult to manage with complex product structures (multi-level BOM)
• Requires highly reliable supply chain

MRP System Details

Operating Principle

MRP calculates required parts and materials by working backward from final product demand. For instance, in aircraft manufacturing, it calculates which parts to order now for a plane to be delivered in 6 months, through thousands of BOM items.

Advantages

• Complex Product Management: Suitable for products with thousands of parts
• Long-term Planning: Advantageous for materials with long procurement lead times
• Capacity Planning: Integrates equipment and workforce planning (MRP II, ERP)

Disadvantages

• Forecast Errors: Incorrect forecasts lead to excess or shortage
• System Dependency: Data accuracy is critical (BOM, inventory, lead times)
• Response Speed: Time required for plan regeneration

Hybrid Strategy: Combined Approach

Modern manufacturing facilities combine both systems.

Real Case: Electronics Manufacturer

• MRP Usage: Critical components with long lead times (semiconductor chips, displays)
• Kanban Usage: Commodity items (cases, screws, packaging materials)
• Result: Strategic procurement of critical parts, waste-free management of consumables

Hybrid Strategy Implementation Points

1. ABC Analysis: Classify parts by value and consumption pattern
2. A-items (high-value, long lead time): MRP planning
3. C-items (low-value, frequent use): Kanban management
4. B-items: Flexible application based on situation

Environment Selection Guide

When Kanban is Suitable

• ✅ Repetitive, high-volume production (automotive, electronics assembly)
• ✅ Relatively stable demand
• ✅ Short production cycles
• ✅ Stable and proximate supply chain
• Examples: Smartphone case manufacturing, beverage production

When MRP is Suitable

• ✅ Complex product structures (aircraft, ships, heavy equipment)
• ✅ Make-to-order/Engineer-to-order (MTO/ETO)
• ✅ Long material procurement lead times
• ✅ Project-based production
• Examples: Industrial plants, special machinery fabrication

Decision Checklist

| Question | Kanban-oriented | MRP-oriented | |----------|-----------------|-------------| | Is product BOM 3 levels or less? | ● | ○ | | Is monthly demand variation within 30%? | ● | ○ | | Are key material lead times within 1 week? | ● | ○ | | Are product specifications standardized? | ● | ○ | | Are there 100+ customer customization options? | ○ | ● |

Conclusion: Production Management in the AI Era

Recently, smart production management has emerged, combining the strengths of both systems using AI-based demand forecasting and real-time data. Securing both MRP's planning capabilities and Kanban's agility is the direction of modern manufacturing. The key is accurately understanding your production characteristics and wisely selecting or mixing appropriate systems.