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