Chapter 14 - JIT and Lean Operations

Lean workers receive training in

-Statistical process control -Quality improvement -Problem solving

Pull System

-a workstation pulls output from the preceding station as it is needed -Output of the final operation is pulled by customer demand or the master schedule Example: JIT

Benefits of small lot sizes

-reduces inventory -less rework -less storage space -problems are more apparent -increases product flexibility -easier to balance operations

Eight sources of waste in lean systems

1. Excess inventory 2. Overproduction 3. Waiting time 4. Unnecessary transporting 5. Processing waste 6. Inefficient work methods 7. Product defects 8. Underused people

Lean System Principles

1. Identify customer values 2. Focus on processes that create value 3. Eliminate waste to create "flow" 4. Produce only according to customer demand 5. Strive for perfection

Critical Risks of Lean Systems

1. Increased stress on workers 2. Fewer resources available if problems occur 3. Supply chain disruptions can halt operations

Transitioning to Lean Systems

1. Make sure top management is committed and that they know what will be required 2. Decide which parts will need the most effort to convert 3. Obtain support and cooperation of workers 4. Begin by trying to reduce setup times while maintaining the current system 5. Gradually convert operations, begin at the end and work backwards 6. Convert suppliers to JIT 7. Prepare for obstacles

Lean: Building Blocks

1. Product design 2. Process design 3. Personnel/organizational elements 4. Manufacturing planning and control

Two main types of Kanban

1. Production kanban (p-kanban): signals the need to produce parts 2. Conveyance kanban (c-kanban): signals the need to deliver parts to the next work center.

Benefits of Lean Systems

1. Reduced waste 2. Lower costs 3. Increased quality 4. Reduced cycle time 5. Increased flexibility 6. Increased productivity

Kaizen Ideas

1. Waste is the enemy, and to eliminate waste it is necessary to get the hands dirty 2. Improvement should be done gradually and continuously; the goal is not big improvements done intermittently 3. Everyone should be involved 4. Kaizen is built on a cheap strategy, and it does not require spending great sums on technology or consultants 5. It can be applied everywhere 6. It is supported by a visual system 7. It focuses attention where value is created 8. It is process oriented 9. It stresses that the main effort for improvement should come from new thinking and a new work style 10. The essence of organizational learning is to learn while doing

Kanban

A Japanese word meaning "card" or "visible record" that refers to cards used to control the flow of production through a factory

Lean Operations

A flexible system of operation that uses considerably less resources than a traditional system. Tend to achieve: Greater Productivity Lower costs Shorter cycle times Higher quality

Just-in-Time Operations

A highly coordinated processing system in which goods move through the system, and services are performed, just as they are needed

5W2H

A method of asking questions about a process that includes what, why, where, when, who, how, and how much.

Single minute exchange of die (SMED)

A system for reducing changeover time Group technology may be used to reduce setup time by capitalizing on similarities in recurring operations

Value Stream Mapping

A visual tool to systematically examine the flows of materials and information

Ultimate Goal of Lean Systems

Achieve a balanced system- One that achieves a smooth, rapid flow of materials and/or work through the system

Poka-yoke (Fail Safing)

Building safeguards into a process to reduce or eliminate the potential for errors during a process Examples: Electrick breakers Seatbelt fastener warnings ATMS signaling if card is left

Kaizen (continuous improvement)

Continuous approach to reduce process, delivery, & quality problems, such as machine breakdown problems, setup problems, & internal quality problems.

Lean Operations: The Beginning

Developed by Taiichi Ohno and Shigeo Ohno of Toyota Focus was on eliminating all waste from every aspect of the process Also known as JIT in the mid-1900s

level loading

Lean systems place a strong emphasis on achieving stable, level daily mix schedules

Seven elements of manufacturing planning and control (MPC)

Level loading Pull systems Visual systems Limited work-in-process (WIP) Close vendor relationships Reduced transaction processing Preventive maintenance and housekeeping

Lean systems seek to reduce costs associated with the 'hidden factory':

Logistical transactions Balancing transactions Quality transactions Change transactions

Benefits of lower WIP

Lower carrying costs Increased flexibility Aids scheduling Saves costs of scrap and rework if there are design changes Lower cycle-time variability

Housekeeping

Maintaining a workplace that is clean and free of unnecessary materials

Preventive maintenance

Maintaining equipment in good operating condition and replacing parts that have a tendency to fail before they actually do fail

Process Design Aspects

Small lot sizes Setup time reduction Manufacturing cells Quality improvement Production flexibility A balanced system Little inventory storage Fail-safe methods

Product Design Elements

Standard parts Modular design Highly capable systems with quality built in Concurrent engineering

Lean System Characteristics

Waste reduction Continuous improvement Use of teams Work cells Visual controls High quality Minimal inventory Output only to match demand Quick changeovers Small lot sizes Lean culture

Five personnel/organizational elements that are important for lean systems

Workers as assets Cross-trained workers Continuous improvement Cost accounting Leadership/project management

JIDOKA

an autonomation concept that focuses on automatic detection of defects in the production process. It aims to both detecting defects while occurring and stopping production to correct the cause of the defects

Well-trained and motivated workers

are the heart of the lean system

Cross-trained workers

are trained to perform several parts of a process and operate a variety of machines, facilitates flexibility, and helps in line balancing

Setup time reduction enables

frequent setups, reduces lot sizes, and allows frequent changes of product mixes

Cost accounting

is an important base for improving cost, quality, process design, product design, and waste reduction

A key feature of many lean systems

is the relatively small number of suppliers used

One characteristic of lean production systems is multiple

manufacturing cells

Lean systems are designed to

minimize inventory storage

Lean Focus

on eliminating non-value-added activity to maximize process velocity

In the lean philosophy, the ideal lot size is

one unit

Six sigma

seeks to eliminate process variation

Takt Time

the cycle time needed to match customer demand for final product Sometimes referred to as the heartbeat of a lean system

Push System

work is pushed to the next station as it is completed Example: MRP

Lean systems encourage two-way communication between

workers and managers