Lean Operations and Scheduling (discussion)
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SEU_MGT530_Module14_PPT_Ch14.pptxLean Operations
Chapter 14
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You should be able to:
LO 14.1 Explain the terms lean operations and JIT
LO 14.2 Describe the main characteristics of lean systems
LO 14.3 List the five principles of the way lean system function
LO 14.4 List some of the benefits and some of the risks of lean operations
LO 14.5 Describe the Toyota Production System (TPS)
LO 14.6 List the three goals of a lean system and explain its importance of each
LO 14.7 List the eight wastes according to lean philosophy
LO 14.8 Identify and briefly discuss the four building blocks of a lean production system
LO 14.9 Describe key lean improvement tools
LO 14.10 Outline considerations for successful conversion from a traditional system to a lean system
LO 14.11 Describe some of the obstacles to lean success
Chapter 14: Learning Objectives
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Lean operation
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
A highly coordinated processing system in which goods move through the system, and services are performed, just as they are needed
Lean Operations
LO 14.1
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A number of characteristics are commonly found in lean systems:
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
Lean System Characteristics
LO 14.2
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Five principles embody the way lean systems function:
Identify customer values
Focus on processes that create value
Eliminate waste to create “flow”
Produce only according to customer demand
Strive for perfection
Lean System Principles
LO 14.3
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Key benefits
Reduced waste
Lower costs
Increased quality
Reduced cycle time
Increased flexibility
Increased productivity
Critical risks
Increased stress on workers
Fewer resources available if problems occur
Supply chain disruptions can halt operations
Benefits & Risks of Lean Systems
LO 14.4
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Lean operations began as lean manufacturing, also known as JIT in the mid-1900s
Developed by Taiichi Ohno and Shigeo Ohno of Toyota
Focus was on eliminating all waste from every aspect of the process
Waste is viewed as anything that interferes with, or does not add value to, the process of producing automobiles
Lean Operations: The Beginning
LO 14.5
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Lean: Ultimate Goal
The ultimate goal:
Achieve a balanced system–
One that achieves a smooth, rapid flow of materials and/or work through the system
LO 14.6
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Lean: Supporting Goals
The degree to which lean’s ultimate goal is achieved depends upon how well its supporting goals are achieved:
Eliminate disruptions
Make the system flexible
Eliminate waste, especially excess inventory
LO 14.6
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Waste
Represents unproductive resources
Eight sources of waste in lean systems:
Excess inventory
Overproduction
Waiting time
Unnecessary transporting
Processing waste
Inefficient work methods
Product defects
Underused people
Waste
LO 14.7
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The kaizen philosophy for attacking waste is based upon these ideas:
Waste is the enemy, and to eliminate waste it is necessary to get the hands dirty
Improvement should be done gradually and continuously; the goal is not big improvements done intermittently
Everyone should be involved
Kaizen is built on a cheap strategy, and it does not require spending great sums on technology or consultants
It can be applied everywhere
It is supported by a visual system
It focuses attention where value is created
It is process oriented
It stresses that the main effort for improvement should come from new thinking and a new work style
The essence of organizational learning is to learn while doing
Kaizen
LO 14.7
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Lean: Building Blocks
Product design
Process design
Personnel/organizational elements
Manufacturing planning and control
LO 14.8
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Four elements of product design important for lean systems:
Standard parts
Modular design
Highly capable systems with quality built in
Concurrent engineering
Building Blocks: Product Design
LO 14.8
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Eight aspects of process design that are important for lean systems:
Small lot sizes
Setup time reduction
Manufacturing cells
Quality improvement
Production flexibility
A balanced system
Little inventory storage
Fail-safe methods
Building Blocks: Process Design
LO 14.8
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In the lean philosophy, the ideal lot size is one
Benefits of small lot size
Reduced in-process inventory
Lower carrying costs
Less storage space is necessary
Inspection and rework costs are less when problems with quality do occur
Permits greater flexibility in scheduling
Less inventory to ‘work off’ before implementing product improvements
Increased visibility of problems
Increased ease of balancing operations
Process Design: Small Lot Sizes
LO 14.8
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Process Design: Setup Time Reduction
Small lot sizes and changing product mixes require frequent setups
Unless these are quick and relatively inexpensive, they can be prohibitive
Setup time reduction requires deliberate improvement efforts
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
LO 14.8
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Process Design: Manufacturing Cells
One characteristic of lean production systems is multiple manufacturing cells
Benefits include
Reduced changeover times
High equipment utilization
Ease of cross-training workers
LO 14.8
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Quality defects during the process can disrupt the orderly flow of work
Autonomation (jidoka)
Automatic detection of defects during production
Two mechanisms are employed
One for detecting defects when they occur
Another for stopping production to correct the cause of the defects
Process Design: Quality Improvement
LO 14.8
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Guidelines for increasing flexibility
Reduce downtime due to changeovers by reducing changeover time
Use preventive maintenance on key equipment to reduce breakdowns and downtime
Cross-train workers so they can help when bottlenecks occur or other workers are absent
Use many small units of capacity; many small cells make it easier to shift capacity temporarily and to add or subtract capacity
Use off-line buffers. Store infrequently used safety stock away from the production area
Reserve capacity for important customers
Process Design: Work Flexibility
LO 14.8
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Takt time
The cycle time needed to match customer demand for final product
Sometimes referred to as the heartbeat of a lean system
Takt time is often set for a work shift
Procedure:
Determine the net time available per shift
If there is more than one shift per day, multiply the net time by the number of shifts
Compute the takt time by dividing the net available time by demand
Process Design: Balanced System
LO 14.8
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Process Design: Inventory Storage
Lean systems are designed to minimize inventory storage
Inventories are buffers that tend to cover up recurring problems that are never resolved
Partly because they are not obvious
Partly because the presence of inventory makes them seem less serious
LO 14.8
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Poka-yoke (Fail-safing)
Building safeguards into a process to reduce or eliminate the potential for errors during a process
Examples:
Electric breakers
Seatbelt fastener warnings
ATMs that signal if a card is left in a machine
Designing parts that can only be assembled in the correct position
Process Design: Fail-Safe Methods
LO 14.8
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Building Blocks: Personnel/Organizational
Five personnel/organizational elements that are important for lean systems:
Workers as assets
Cross-trained workers
Continuous improvement
Cost accounting
Leadership/project management
LO 14.8
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Workers as assets
Well-trained and motivated workers are the heart of the lean system
They are given greater authority to make decisions, but more is expected of them
Personnel/Organizational: Workers as Assets
LO 14.8
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Cross-trained workers
Workers are trained to perform several parts of a process and operate a variety of machines
Facilitates flexibility
Helps in line balancing
Personnel/Organizational: Cross-Trained Workers
LO 14.8
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Continuous improvement
Workers in lean systems have greater responsibility for quality, and they are expected to be involved in problem solving and continuous improvement
Lean workers receive training in
Statistical process control
Quality improvement
Problem solving
Personnel/Organizational: Continuous Improvement
LO 14.8
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Personnel/Organizational: Cost Accounting
Cost accounting
Activity-based costing
Allocation of overhead to specific jobs based on their percentage of activities
LO 14.8
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Personnel/Organizational: Leadership
Leadership/project management
Managers are expected to be leaders and facilitators, not order givers
Lean systems encourage two-way communication between workers and managers
LO 14.8
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Seven elements of manufacturing planning and control (MPC) are particularly important for lean system:
Level loading
Pull systems
Visual systems
Limited work-in-process (WIP)
Close vendor relationships
Reduced transaction processing
Preventive maintenance and housekeeping
Building Blocks: MPC
LO 14.8
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MPC: Level Loading
Lean systems place a strong emphasis on achieving stable, level daily mix schedules
MPS – developed to provide level capacity loading
Mixed model scheduling
Three issues need to be resolved
What is the appropriate product sequence to use?
How many times should the sequence be repeated daily?
How many units of each model should be produced in each cycle?
LO 14.8
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Push system
Work is pushed to the next station as it is completed
Pull system
A workstation pulls output from the preceding workstation as it is needed
Output of the final operation is pulled by customer demand or the master schedule
Pull systems are not appropriate for all operations
Large variations in volume, product mix, or product design will undermine the system
MPC: Pull Systems
LO 14.8
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Kanban
Card or other device that communicates demand for work or materials from the preceding station
Kanban is the Japanese word meaning “signal” or “visible record”
Paperless production control system
Authority to pull, or produce, comes from a downstream process
Two main types of kanbans:
Production kanban (p-kanban): signals the need to produce parts
Conveyance kanban (c-kanban): signals the need to deliver parts to the next work center
MPC: Visual Systems
LO 14.8
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MPC: Limited WIP
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
LO 14.8
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MPC: Close Vendor Relationships
Lean systems typically have close relationships with vendors
They are expected to provide frequent, small deliveries of high-quality goods
A key feature of many lean systems is the relatively small number of suppliers used
LO 14.8
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Lean systems seek to reduce costs associated with the ‘hidden factory’:
Logistical transactions
Balancing transactions
Quality transactions
Change transactions
MPC: Reduced Transaction Processing
LO 14.8
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Preventive maintenance
Maintaining equipment in good operating condition and replacing parts that have a tendency to fail before they actually do fail
Housekeeping
Maintaining a workplace that is clean and free of unnecessary materials
Preventive Maintenance and Housekeeping
LO 14.8
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Value stream mapping
A visual tool to systematically examine the flows of materials and information
Its purpose is to help identify waste and opportunities for improvement
Data collected:
Times
Distances traveled
Mistakes
Inefficient work methods
Waiting times
Information flows
Lean Tools: Value Stream Mapping
LO 14.9
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5W2H
A method of asking questions about a process that includes what, why, where, when, who, how, and how much
Lean and Six Sigma
Lean and Six Sigma can be viewed as two complementary approaches to process improvement
Lean focuses on eliminating non-value-added activity to maximize process velocity
Six Sigma seeks to eliminate process variation
Together the two approaches can achieve process flow and quality
Lean Tools: 5W2H & Six Sigma
LO 14.9
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Make sure top management is committed and that they know what will be required
Decide which parts will need the most effort to convert
Obtain support and cooperation of workers
Begin by trying to reduce setup times while maintaining the current system
Gradually convert operations, begin at the end and work backwards
Convert suppliers to JIT
Prepare for obstacles
Transitioning to Lean Systems
LO 14.10
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Management may not be fully committed or willing to devote the necessary resources to conversion
Workers/management may not be cooperative
It can be difficult to change the organizational culture to one consistent with the lean philosophy
Suppliers may resist
Obstacles to Conversion
LO 14.11
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