Lean Manufacturing

Definition

Lean Manufacturing – A way to eliminate waste and improve efficiency in a manufacturing environment

Lean focuses on flow, the value stream and eliminating muda, the Japanese word for waste

Lean manufacturing is the production of goods using less of everything compared to traditional mass production: less waste, human effort, manufacturing space, investment in tools, inventory, and engineering time to develop a new product

Lean and Just-in-Time

Lean was generated from the Just-in-time (JIT) philosophy of continuous and forced problem solving

Just-in-time is supplying customers with exactly what they want when they want it

With JIT, supplies and components are “pulled” through a system to arrive where they are needed when they are needed

What is Waste?

Waste is anything that happens to a product that does not add value from the customer’s perspective

Products being stored, inspected or delayed, products waiting in queues, and defective products do not add value

Seven Wastes

Overproduction – producing more than the customer orders or producing early. Inventory of any kind is usually waste.

Queues – idle time, storage, and waiting are wastes Transportation – moving material between plants,

between work centers, and handling more than once is waste

Inventory – unnecessary raw material, work-in-process (WIP), finished goods, and excess operating supplies

Motion – movement of equipment or people Overprocessing – work performed on product that

adds no value Defective product – returns, warranty claims,

rework and scrap

Origins

Lean Manufacturing is sometimes called the Toyota Production System (TPS) because Toyota Motor Company’s Eiji Toyoda and Taiichui Ohno are given credit for its approach and innovations

Underlying Principles to TPS

Work shall be completely specified as to content, sequence, timing, and outcome

Every customer-supplier connection, both internal and external, must be direct and specify personnel, methods, timing, and quantity of goods or services provided

Product and service flows must be simple and direct – goods and services are directed to a specific person or machine

Any improvement in the system must be made in accordance with the “scientific method” at the lowest possible level in the organization

Toyota Production System

Since the Toyota Production System requires that activities, connections, and flow paths have built-in tests to signal problems automatically, gaps become immediately evident.

Results of the TPS are improvements in reliability, flexibility, safety, and efficiency.

These lead to increase in market share and profitability.

Key Lean Manufacturing Techniques

5S

Single Minute Exchange of Dies

Kanban

Cellular Manufacturing

5S

Strategy for creating a well organized, smoothly flowing manufacturing process

5S Examples

Before After

Benefits of 5S

Increases organization and efficiency

Avoids wasted motion Increases safety Eliminates unnecessary inventory Offers improvements at an

inexpensive cost

5S Drawbacks

If not fully implemented, may result in “Jive S” Store things Stick to the rules Superficially clean Switch to new fixtures Serve reluctantly

Can not be considered an end goal – must be part of a continuous improvement movement

Single Minute Exchange of Dies (SMED)

Method that focuses on the rapid conversion from manufacturing one product to the next

SMED Examples

Benefits of SMED

Increases throughput by reducing setup times

Eliminates setup errors Increases safety Reduces the cost of setups Reduces waiting times and inventory

buildups Decreases the required skill level of

the operators

Kanban

A system that uses replenishment signals to simplify inventory management Signals (usually cards) hold product details

What to make, when to make it, how much to make, and where to send it

Cards stay attached to a bin that holds the product

When bin is empty, it is returned to the start of the assembly line for replenishment

Full bins are returned to the customer, and the cycle continues

Kanban Example

Supermarket Ordering System

Benefits of Kanban

Highly visible systems Simple, effective, and inexpensive Reduces inventory and eliminates

stock-outs Improves the quality of service Improves lead times

Cellular Manufacturing

Dividing the manufacture of products into semi-autonomous and multi-skilled teams known as work cells

Benefits of Cellular Manufacturing

Simplifies material flow and management

Reduces interdepartmental travel Reduces throughput time Reduces lot sizes Simplifies scheduling

Lean Manufacturing Advantages and Disadvantages

Advantages: Increased overall

productivity Reduced amount of

floor space required Reduced

manufacturing lead time

Improved flexibility to react to changes

Improved quality

Disadvantages: Difficulty involved

with changing processes to implement lean principals

Long term commitment required

Very risky process - expect supply chain issues while changing over to lean

How People Benefit from Lean

Element Traditional Lean Improvement

Communication Slow & Uncertain Fast & Positive Quality & Coordination

Teamwork Inhibited Enhanced Effective Teams

Motivation Negative, Extrinsic Positive, Intrinsic Strong Motivation

Skill Range Narrow Broad Job Enrichment

Supervision Difficult and Fragmented

Easy & Localized Fewer Supervisors

How Customer’s Benefit from Lean

Element Traditional Lean Improvement

Response Weeks Hours 70-90%

Customization Difficult Easy Competitive Advantage

Delivery Speed Weeks-Months Days 70-90%

Delivery Reliability

Erratic Consistent & High Up to 90%

Delivery Quantities

Large Shipments JIT as Required Locks in JIT Customers

Quality Erratic Consistent & High Delighted Customers

Economics

Reduction of Inventory Less space necessary to hold inventory

Reduced Waste Decreased Production Cost

Increased market share Able to provide what the customer wants

quickly Increased competitive advantage

Faster response to the customer Lower Cost Higher Quality

Quality Control

6 sigma process Combination of old and new ideas

6 ingredients Genuine focus on the customer Data- and fact-driven management Process focus, management, and improvement Proactive management Boundarlyless collaboration Drive for perfection, tolerance failure