Abstract :
In this
world of competition without proper production management a company cannot
survive. Using a manufacturing concept for competitive advantage is
relatively a new concept. Lean manufacturing is a concept actually brought up y Toyota motor
company, Japan. But it was popularized to the world by the book “THE MACHINE
THAT CHANGED THE WORLD” by Womack, Jones and Roos of MIT in
1990. Adding
value by eliminating waste, being responsive to changes, focusing on quality
and enhancing effectiveness of workforce is what achieved by lean
manufacturing. It needs a systematic and continuing search for non
value added activities. This seminar provides an overview of basic elements, techniques
and benefits of lean manufacturing.
WHAT IS LEAN MANUFACTURING?
Lean
manufacturing is a manufacturing system and philosophy that was originally
developed by Toyota, Japan and is now used by many manufacturers
throughout the world. Lean Manufacturing can be defined as: "A
systematic approach to identifying and eliminating waste (non-value-added
activities) through continuous improvement by flowing the product at the pull
of the customer in pursuit of perfection." The term lean manufacturing is a more generic term
and refers to the general principles and further
developments of becoming lean. The term lean is very apt because in lean manufacturing the
emphasis is on cutting out “FAT” or wastes in manufacturing process. Waste is
defined as anything that does not add any value to the product. It could be
defined as anything the customer is not willing to pay for. Manufacturing philosophy is pivoted on designing a
manufacturing system that perfectly blends together the fundamentals of
minimizing costs and maximizing profit. These fundamentals are Man (labour),
Materials and Machines (equipments) called the 3 M’s of manufacturing. A
well-balanced 3M is resulted through lean manufacturing.
WASTES IN
MANUFACTURING
The aim of Lean Manufacturing is the
elimination of waste in every area of production including customer relations,
product design, supplier networks, and factory management. Its goal is to
incorporate less human effort, less inventory, less time to develop products,
and less space to become highly responsive to customer demand while producing
top quality products in the most efficient and
economical manner possible. Essentially, a "waste" is anything that the customer is
not willing to pay for.Typically the types of waste considered in a lean manufacturing
system include:
3.1
Overproduction
To produce
more than demanded or produce it before it is needed. It is visible as storage
of material. It is the result of producing to speculative demand.
Overproduction means making more than is required by the next process, making
earlier than is required by the next process, or making faster than is required
by the next process.
Causes for
overproduction waste include:
Just-in-case
logic
Misuse of
automation
Long
process setup
Unleveled
scheduling
Unbalanced
work load
Over
engineered
Redundant
inspections
3.2 Waiting
For a
machine to process should be eliminated. The principle is to maximize the
utilization/efficiency of the worker instead of maximizing the utilization of
the machines.
Causes of
waiting waste include:
Unbalanced
work load
Unplanned
maintenance
Long
process set-up times
Misuses of
automation
Upstream
quality problems
Unleveled
scheduling
3.3
Inventory or Work in Process (WIP)
This is
material between operations due to large lot production or processes with long
cycle times. Causes of excess inventory include:
Protecting
the company from inefficiencies and unexpected problems
Product
complexity
Unleveled
scheduling
Poor market
forecast
Unbalanced
workload
Unreliable
shipments by suppliers
Misunderstood
communications
Reward
systems
3.4 Processing waste It should be minimized by asking why a specific
processing step is needed and why a specific product is produced. All
unnecessary processing steps should be eliminated. Causes for processing waste
include:
Product
changes without process changes
Just-in-case
logic
True
customer requirements undefined
Over
processing to accommodate downtime
Lack of
communications
Redundant
approvals
Extra
copies/excessive information
3.5 Transportation This does not add any value to the product. Instead
of improving the transportation, it should be minimized or eliminated (e.g.
forming cells). Causes of transportation waste include:
Poor plant
layout
Poor
understanding of the process flow for production
Large batch
sizes, long lead times, and large storage areas
3.6 Motion Motion of the workers, machines, and transport (e.g.
due to the inappropriate location of tools and parts) is waste. Instead of
automating wasted motion, the operation itself should be improved. Causes of motion waste include:
Poor
people/machine effectiveness
Inconsistent
work methods
Unfavorable
facility or cell layout
Poor
workplace organization and housekeeping
Extra
"busy" movements while waiting
3.7 Making defective products This is pure waste. Prevent the occurrence of
defects instead of finding and repairing
defects. Causes of
processing waste include:
Weak
process control
Poor
quality
Unbalanced
inventory level
Deficient
planned maintenance
Inadequate
education/training/work instructions
Product
design
Customer
needs not understood
3.8
Underutilizing people Not taking advantage of people's abilities. Causes
of people waste include:
Old guard
thinking, politics, the business culture
Poor hiring
practices
Low or no
investment in training
Low pay,
high turnover strategy
Nearly
every waste in the production process can fit into at least one of these
categories. Those that understand the concept deeply view waste as the singular
enemy that greatly limits business performance and threatens prosperity unless
it is relentlessly eliminated over time. Lean manufacturing is an approach that
eliminates waste by reducing costs in the overall production process, in
operations within that process, and in the utilization of production labor. The
focus is on making the entire process flow, not the improvement of one or more
individual operations.
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