LEAN MANUFACTURING

By Eng. Tarek SaafanQA Manager Misr Compressors

Objectives

To achieve a common definition and vision ofLean Manufacturing

Be able to identify manufacturing system wastes

Understand Lean principles To provide an overview of the Lean tools and

techniques To understand Benefits of Lean Manufacturing

Lean Manufacturing Definition

Is about doing more with Less. Less time, Less inventory, Less space, Less people & money.

Is a philosophy, based on the Toyota Production System, and other Japanese management practices that strive to shorten the time line between the customer order and the shipment of the final product, by consistent elimination of waste.

Is about operating the most efficient and effective organization possible with the least cost and zero waste

Definition Of Work Components

wastevalue creationWORK

Increases costs and reduces

quality

Customers only want to pay

for this

Lean History

In 1945, Toyoda challenged Taiichi Ohno to learn how to compete with US Automakers not on building large volumes of similar models, but many models in low volume.

Ohno was given 3 years to develop a system to achieve this goal.

Ohno went to the US and studied Ford mass assembly processes at the Rouge River Plant.

Ohno learned a lot from this experience, but felt Ford stopped short of a better system.

Ohno also studied the supermarket concept of ordering and replenishing stock by a signal system. This resulted in Ohno applying the KANBAN concept to the system he would develop

Cont. Lean History

It took Ohno over 20 years to develop the system that became known as The Toyota Production System (TPS)

It took until the 1974 Oil Crisis before outsiders and others in Japan really took notice of the TPS system that Ohno built and the way it was allowing Toyota to compete when others were faltering.

Lean Manufacturing came to the US with James Womack’s Book, “ The Machine That Changed The World” in 1990.

Focused on Toyota Production System Concepts and Why Toyota was able to so successful over US Auto Manufacturers.

Lean benefits

90% reduction in lead time (cycle time). 50% increase in productivity. 80% reduction in work-in-process inventory. 80% improvement in quality. 75% reduction in space utilization.

The Lean Definition of Waste

Waste is anything that does not add value to your product or service

It is anything other than the minimum amount of equipment, materials, parts, space and employees' time which is absolutely essential to add value to the product or service.

Necessary activities add Value Unnecessary or wasteful activities add Cost

Seven Basic Types of Waste

Waste from overproduction Waste from waiting times Transportation waste Processing Waste Inventory Waste Waste of motion Waste from product defects

Waste of Overproduction

If you make more product than is required by the next process, make it earlier than is required by the next process, or make product faster than is required by the next process, you overproduce.

Waste of Overproduction

Extra handling

Extra space

Extra interest charges

Extra defects

Extra overhead

Extra peopleExtra paperwork

Extra inventory

Waste from Waiting times

Operator or machine idle time.

Causes of Waiting Waste Unbalanced work load & un-level

scheduling Unplanned maintenance Long process set-up times Upstream quality problem.

Waste of Transportation

Transporting parts and materials around the plant without adding value

Causes: Poor plant layout Poor understanding of the process

flow for production Large batch sizes, long lead times,

and large storage areas.

Processing Waste Effort that adds no value to the product or service from the customers’ viewpoint

Causes: Product changes without process changes True customer requirements undefined Over processing to accommodate downtime

Inventory Waste

Maintaining excess inventory of raw materials, parts in process, or finished goods.

Causes of excess inventory Protects the company from inefficiencies

and unexpected problems. Product complexity Unbalanced workload, unleveled

scheduling Poor Market forecast Unreliable shipments by suppliers

Inventory Hides ProblemsInventory Hides Problems

Scrap

Work in process inventory level(hides problems)

Unreliable Vendors Capacity Imbalances

Less Inventory Exposes ProblemsLess Inventory Exposes Problems

Scrap

Reducing inventory revealsproblems so they can be solved.

Unreliable Vendors Capacity Imbalances

WIP

Waste of motion

Any movement of people or machines without adding value

Causes: Poor people/machine

effectiveness Inconsistent work methods Unfavorable facility or cell

layout Poor workplace organization

and housekeeping

Waste from product defects

All the time and cost incurred due to getting something wrong

Causes: Weak process control Poor product & process design Deficient planned maintenance Inadequate education/training/work

instructions Misunderstood Customer needs.

Lean Principles

Precisely define value by specific product. Identify the value stream for each product. Make the value flow without interruptions. Let the customer pull value from the

producer. Pursue perfection.

Lean Building Blocks

ValueStreamMapping

Visual Controls

The Lean Factory

5S System

Quick SetupsMistake Proofing

PULL / Kanban Cellular Layout TPM

Standard Work

Self Inspection

Batch Reduction

Standard Work

Standard work means that production processes and guidelines are very clearly defined and communicated, in a high level of detail, so as to eliminate variation and incorrect assumptions in the way that work is performed.

The goal is that production operations should be performed the same way every time, except insofar as the production process is intentionally modified.

Standard Work Elements

Standard work sequence - This is the order in which a worker must perform tasks, including motions and processes. This is clearly specified to ensure that all workers perform the tasks in the most similar ways possible so as to minimize variation and therefore defects.

Standard timing – Takt time is the frequency with which a single piece is produced. Takt time is used to clearly specify and monitor the rate at which a process should be occurring at

various production stages. Standard in-process inventory – This is the

minimum unit of materials, consisting primarily of units undergoing processing, which are required to keep a cell or process moving at the desired rate.

Mistake proofing (Poka Yoke)

POKA = ERRORSERRORS

YOKE = AVOIDAVOID

Poka-yoke is a Japanese improvement strategy for mistake-proofing to prevent defects (or nonconformities) from arising during production processes.

The Poka-yoke concept was created in the mid-1980s by Shigeo Shingo, a Japanese manufacturing engineer.

Shingo lists characteristics of poka-yoke devices:

1. 100 percent inspection is possible

2. Devices avoid sampling for monitoring and control

3. Poka-yoke devices are inexpensive

Poka Yoke Methods

Shutdown. Poka-yoke devices monitor critical process

conditions and shut down the process when a parameter moves out of the desirable range, indicating that a defective product has either been produced or is about to be produced.

Control. Poka-yoke devices are installed on process equipment and/or work pieces, making it impossible to produce defects and/or to flow a nonconforming product onto the next process.

Warning. Poka-yoke devices signal to a worker that a defect has been produced. The worker must intervene to correct the processes responsible for causing the defect, since otherwise the processes will output further nonconforming product.

Poka Yoke Examples

Poka Yoke Industrial Examples

In this example, each step of the machine cycle is wired to an indicator board and a timer. If each cycle of the machine is not performed within the required “time” and “sequence”, the indicator light for that step will be turned on and the machine will stop.

Indicator BoardMachine

Cont. Poka Yoke Industrial Examples

Warning sensors connected to lights

Used to physically detect the presence or absence of an object or item-prevents missing parts.

Used to physically detect the height of a part or dimension.

Visual Controls

Simple signals that provide an immediate understanding of a situation or condition.

Three reasons for using visual management tools:

1. To make problems visible

2. To help workers and management stay in direct contact with the workplace

3. To clarify targets for improvement A Visual Workplace includes:

Visual Orders Visual Standards Visual Measures Visual Controls

Visual Controls Examples

Cont. Visual Controls

The 5 S

Sort - Everything in the work area. Sort through, then sort out. “When in doubt, throw it out!”

Set In Order - Organize everything that remains. Shine - Clean everything; ceilings, walls, floors, equipment, cabinets,

desks, tooling, etc. Standardize - Make it obvious where things belong, using lines, labels,

signs, shadow boxes, shadow boards, etc. Sustain - Create rules, guidelines, cleaning charts, action lists, etc.

Use display boards, newsletters, and give recognition to sustain successes.

The 5S System is a Japanese series of activities designed to improve workplace organization and standardization. These activities, all of which begin with the letter S, include:

Before and After 5 S

Quick Setups (SMED) Single Minute Exchange of Die (SMED) concept is to take a long

setup change of perhaps 4 hours in length and reduce it to 3 minutes.

Shigeo Shingo, developer of the SMED system has used it quite effectively in the Toyota Production System for just-in-time production.

Single minute exchange of die does not literally require die changes to be performed in only one minute, it merely implies that die changes are to be accomplished under a single digit of time (nine minutes or less).

SMED is a system that reduces the dependence on the long term experience of operators to perform an effective changeover. SMED will have a system to reduce the skill level needed for setup changes.

Internal setup: Can be performed only when a process is stopped External setup: Can be performed in advance

SMED Principles

Separate internal setup from external setup Convert internal setup to external setup Streamline all aspects of setup Perform setup activities in parallel or eliminate

them entirely

SMED Techniques

Cont. SMED Techniques

Cellular layout

Cellular layout is a technique of arranging operations and/or people in a cell (U-shaped, etc.) rather than in a traditional straight assembly line.

Cellular layout helps to achieve many of the objectives of Lean Manufacturing due to its ability to help eliminate many non value-added activities from the production process such as waiting times, bottlenecks, transport and works-in-progress.

Cellular Layout Characteristics Continuous flow - There is a smooth flow of materials and

components through the cell with virtually no transport or waiting time between production stages.

One-piece flow - Cellular manufacturing utilizes a one piece flow so that one product moves through the manufacturing process one piece at a time.

Multi-purpose workers - There is only one or several workers in each cell and unlike batch processing where workers are responsible for a single process, in cell manufacturing the cell workers are responsible for handling each of the different processes that occur in the cell. Therefore each worker is trained to handle each process which occurs within the cell.

U-shape – Cells are usually U-shaped, with the product moving from one end of the U to the other end of the U as it is processed by the worker(s). The purpose of this is to minimize the walking distance and movement of materials within a cell.

Kanban / Pull system If the company is not producing what the customer wants than it

is still waste. This is where the concept of pulling demand from the customer,

rather than pushing product. In a production plant, each process can be considered as a

customer to the previous process. Various methods such as Kanban (Japanese word for signal) are used to communicate to the previous process the exact requirement of this process.

The kanban carries information regarding the part number, quantity, location, delivery frequency, etc.

The kanban travels with the actual parts and this system is a simple, seemingly foolproof way to make sure the right parts are made at the right time in the right amount.

The Kanban may be an empty square marked on the floor, an empty shelf, a card describing the parts required, or an electronic signal.

Push Manufacturing

Batch process where resources are provided to the consumer based on forecasts or schedules Complex schedule and material handling Excessive inventory Poor communication Long lead times Large lots

Pull System

A simple, flexible method of controlling & balancing the flow of resources.

Eliminating waste of handling, storage, expediting, repair, rework, facilities, equipment, excess inventory (work-in-process and finished).

Pull System consists of: Production based on actual consumption Small Lots Low Inventories Management by Sight Better Communication

Batch Size Reduction

Historically, manufacturing companies have operated with large batch sizes in order to maximize machine utilization.

Lean calls for the production of parts to customer demand, the ideal batch size is ONE.

A batch size of one is not always practical, so the goal is to practice continuous improvement to reduce the batch size as low as possible.

Reducing batch sizes reduces the amount of work-in-process inventory (WIP).

Therefore, smaller batch sizes shorten the overall production cycle, enabling companies to deliver more quickly and to invoice sooner (for improved cash flow). Shorter production cycles increases inventory turns and allows the company to operate profitably at lower margins, which enables price reductions, which increases sales and market share.

Total Productive Maintenance

TPM combines preventive maintenance and total quality concepts

TPM aims at improving existing plant conditions and at increasing the knowledge and skills of frontline personnel in order to achieve zero accidents, zero defects, and zero breakdowns.

TPM goes beyond preventive maintenance, to optimize the operation of the equipment.

TPM assigns basic preventative maintenance work including inspection, cleaning, lubricating, tightening and calibration to the production workers who operate the equipment.

In TPM, the maintenance team is responsible for the higher value-added maintenance activities such as improving the equipment, performing overhauls and improvements, fixing problems and providing training.

Self inspection

The main responsibility for quality inspection is done in-line by workers, not by separate quality inspectors who inspect sample lots.

Although some independent Quality Control (QC) inspectors are often still used in lean companies, their role is minimized (ideally there are no QC inspectors because they also are considered a waste in Lean Manufacturing

Lean Manufacturing

WASTE

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