Abstract :
This article
presents an overview of methods and tools of Lean Manufacturing,
which are used in enterprises to improve production processes. Article aims to
introduce the reader to both the most commonly used tools as well as those less
known. A description of each method contains an overview of the assumptions,
the main objectives and expected results. The article described tools such as
VSM, 5S, SMED, Jidoka, standardization work, Poka-Yoke, Heijunka, TPM, Hoshin
Kanri, Kamishibai, Kanban and the philosophy of Kaizen.
1. Introduction
The company's
situation depends in large part from the a rapid response to changing customer
requirements. Currently, the standard becomes to produce the products exactly
on time, in the desired quantity and quality and with the lowest competitive
price. All these activities, of course, must also generate a certain profit for
the company.
Enterprise to
achieve its objectives, and most of all to achieve a competitive advantage in
the market must pay special attention to reducing production costs. During the
implementation of subsequent operations arises value of manufactured products
thus creating a value stream. It is important that the individual a value
consisting of the price of the product was acceptable by klienów. That is why
more and more importance to improvement of production processes. Improvement is
to identify and eliminate losses occurring in production.
The concept,
which allows the improvement of production processes is Lean Manufacturing
(LM). It presumes the elimination of all waste occurring on the production
(Japanese. Muda), which leads to a reduction in the transit time of the
material by the process (in English. Lead time). Lean Manufacturing is derived
from the production system TPS (Toyota Production System), whose creators are
Japanese engineers: Sakichi Toyoda, Ki'ichirō Toyoda and Taiichi Ohno. To
achieve its goals manufacturing companies use a variety of tools and methods of
Lean Manufacturing. These include: SMED (ang. Single Minute Exchange of Die),
TPM (ang. Total productin Maintenance), 5S, Poka-Yoke, and other
2. Types of waste
The essence of
Lean Manufacturing is the elimination of all waste occurring in the enterprise.
This shortens the time between ordering and sending the finished goods to the
customer and increase productivity and reduce manufacturing costs. Taiichi Ohno
in his work dedicated to Lean Manufacturing listed seven types of waste:
overproduction, inventory, mistakes and quality defects, waiting,
over-processing, unnecessary transport and unnecessary movement. Currently,
seven types of waste is enriched by yet another - untapped potential employee's.
Overproduction is
understood as the production of products in advance and in greater quantities
than required by the customer. Overproduction is considered the most dangerous
type of waste, because it translates into significant costs associated eg.
Storage, and is the beginning of other waste. Inventories are keeping more
materials, raw materials, work in progress and finished products than the
required minimum. Wastage is the result of overproduction. Can lead to damage
or destruction of products and generates significant transportation and storage
costs. Mistakes and quality defects is understood as work that is not completed
with positive results. Waiting for a product is the time lost due to the
expectations of people, material, information, or tool that does not add value
in the manufacturing process. Excessive processing steps are necessary in terms
of the value added, which however must be implemented in order to produce the
product. This waste is understood as well as taking unnecessary time for the
implementation of customer demand, as well as the use of sophisticated and
costly technologies without justification. Excess transoprt unnecessary
movement of materials, semi-finished or finished products within the company.
This leads to increased production costs and increase the risk of destruction
or damage to the product. Superfluous movement is not adding any value of
physical employee. It results most often from inadequate organization of the
work. The last type waste is underspending the potential employee. In this
context, it is meant ignoring or underspending ideas, competence, talent and
time employee.
3. Methods
of Lean Manufacturing
In this review
article such tools and methods of Lean Manufacturing as: VSM, 5S, SMED, Kanban,
Jidoka, Hoshin Kanri, Heijunka, Standardized Work, Poka-Yoke, Kamishibai,
Kanban and Kaizen philosophy will be presented.
VSM - Value
Stream Mapping
A tool widely
used in enterprises is VSM – Value Stream Mapping. VSM is a graphical way of
presenting material and information flow in the production system. Map shows
all the tasks undertaken in the process, from the purchase of raw materials and
ending with the delivery of finished products to the customer. This analysis
allows the identification of all kinds of waste and orientation for further
action in order to eliminate them.
5S method
Another method
used for the improvement of production processes is the 5S method. 5S is the
basis for the implementation of Lean Manufacturing. The method name is derived
from the first letters of the Japanese words: Seiri, Seiton, Seiso, Seiketsu,
Shitsuke. They are also the names of the five stages of organization of the
work :
1. Seiri – sorting, selection – the
elimination of the workstation of all the items that are unnecessary to do the
job. Step is carried primarily of decreased inventory, and better use of
working space. In accordance with the principle of selection, all unnecessary
items should be marked with a red label and placed in a designated area.
2. 2. Seiton
– systematics – arrangement, designation and selecting a suitable place for all
tools in the workstation at the selection stage. It can help in this instance.
board of shadows or color coding each tool. Step is performed to reduce
unnecessary traffic employee performed when searching for tools and elimination
of errors the quality of products resulting from mistakes by properly marking
items.
3. Seiso - cleaning – cleaning and maintenance
of the workplace and sets out the standard of proper cleaning. Stage aims to:
maintain positions in good condition, identify and eliminate the causes of
pollution and care of machines.
4. Seiketsu – standardize – determine the
rules for the first three stages of 5S. In this stage, mainly defines the
responsibilities of employees and creates instructions, supporting the
execution of the previous steps. Stage provides a systematic procedure and
repeatability previously entered changes.
5. Shitsuke – discipline – ratcheting up at
the habits of employees to comply with the previously introduced changes and
act in accordance with the standards. It is a difficult and long stage, because
it forces you to change the habits of both production workers and management.
5S method does not require large financial
investment, it allows for the creation and maintenance of jobs in governance
functions and cleanliness shapes and proper organization of the working
environment. It is also the first step in strengthening the employees a sense
of ownership in relation to the workplace.
SMED – Single
Minute Exchange of Die.
This method
allows for shortening to a single minute changeover time is SMED. Developer
methods Shingeo Singo has identified four stages of process improvement changeover
equipment.
-
analysis of the current state workstation,
-
separation operations changeover operations
internal and external,
-
transform internal operations in external,
-
to improve all aspects of the changeover.
The action of
bringing the greatest effect in minimizing changeover time is to transform the
operations of internal external. Internal operations, are those whose performance
takes place during the machine downtime. External, are activities that are
performed before and after the stoppage. The more steps will have to move
beyond the stop associated with the changeover, the more time can be spent on
production.
Standardized work
Standardization
work is a tool used Lean Manufacturing for the improvement of work and improves
the sustainability of production processes. Standardization means uniformly
operations, or tasks by all operators. Standardized Work is the best method of
operation. This allows the exercise of all steps in the same way, in the same
order and time, at a fixed cost. Standardization also assumes continuous
development of new, better standards, so as to adapt to the constantly changing
customer requirements.
TPM – Total
Productive Maintenance
TPM is a tool LM
used to eliminate waste associated with technological machines in the
enterprise. TPM is a way of management, integrating all employees to maintain
of production continuity [8]. The main objective of this method is to increase
the efficiency and productivity of machinery and equipment by: a marked
decrease the number of failures, reducing the time retooling
and adjusting
machines and short downtimes and idle (caused frequently absent employee, or
waiting for the tools, material, information, etc.), reducing defects in
product quality, decreased time spent on start-up of production.
Kanban
Kanban is a
Japanese method of production control, which assumes control not based of the
production schedule, and through events occurring directly on production. The
use of Kanban allows for almost total elimination of pre-magazines (the stock
is on the workstation), interoperable, and finished products. The raw materials
are delivered from suppliers with hourly precision, , and thanks to reserves,
production capacity and flexibility of the production process it is possible to
produce almost any product at any time. In contrast, production orders are
closely synchronized with orders received from customers [3].
Kaizen Philosophy
Kaizen philosophy
is the concept of continuous improvement, which assumes constant search for
ideas to improve all areas of the organization. It requires the involvement of
all the company's employees, operators, up to the highest level of management.
The aim of Kaizen is permanently replacing waste activities adding value. In
practice Kaizen comes to collecting and implementing ideas of employees, which
serve to improve the organization of work, or improving the production process.
Jidoka
The notion of
Jidoka refers to the ability to stop the production line or machine by the
operator at the time of the appearance of a malfunction or problems during
manufacture. Problems may be related to the quality of products and delays the
manufacturing process due to a lack of material, tool information. Equipment
operators the ability to detect emerging anomalies and immediately stop the
operation, it allows for a more efficient production process. Tools that enable
the implementation of the rules Jidoka are: Poka-Yoke and Andon.
Poka-Yoke
Poka-Yoke (jap.
Show - any error, Japanese. Yoke - prevention) is a method of preventing errors
coming from mistakes. The main principle in the system Poka- Yoke is that the
errors are to blame processes, not the employees. Poka- Yoke solution is
characterized to prevent any errors in the process. With Poka-Yoke is also
possible to obtain reduced time required for training employees, eliminating
many qualility control operations (or its total elimination), reducing the
amount of defects and a 100% control of the process. An example of a Poka-Yoke
solution is a SIM card, which can be put on the phone only one way through the
angled corner.
Heijunka
Heijunka, or
leveling production is mainly aimed at eliminating jumps in production.
Leveling production is known as a method of sequencing products in order to
balance the production, increase productivity and flexibility by eliminating
waste and minimizing differences in load workstations [6]. Balancing production
is understood as to avoid sudden jumps in the amount of manufactured products
in the schedule [20]. Production leveling consists in determination of the
sequence and the amount of flow from the process, so that current demand was
realized from the warehouse / supermarket and did not cause sudden changes in
the production schedule. Production schedule should be in a given period of
time constant (time largely depends on the seasonality of products). The aim is
to ensure that the products were produced in a particular sequence in batches
of as few pieces. In other words, production leveling is a way of ensuring the
availability of products for customers through a repeatable and uniform flow of
products and supplies in the warehouse. Repeatable flow of products from production
also contributes to load balancing workstations.
Hoshin Kanri
Hoshin Kanri is a method that allows to focus all the company's
ability to improve its performance through the development of a unified policy
and annual management plans based on the basic concept of the company's
management. Hoshin Kanri can have various applications in the enterprise,
starting with strategic planning methods and tools to manage complex projects,
the quality management system (new products are manufactured in the company as
a response to customer demand) up to the operating system, ensuring stable
earnings growth. The actions of this method are carried out in the following
stages :
- 1. to define the
mission and vision in the context of an overall strategy;
2. defining
strategic objectives (3 - 5 years);
3. defining
annual targets;
4. transferring
targets at lower levels;
5. implementation
of the objectives;
6. inspections
objectives;
7. annual
evaluation of the realization of the objectives.
Kamishibai
Kamishibai is a set of simple audits, which are designed to control
the work, use of methods LM, as well as to teach the person controlling find
possible improvements to the process or position. A key element of this system
is an array Kamishibai, which is placed directly on the production line. For
the layout prepared a layout line schedule for conducting audits and
documentation for the auditor. Application Kamishibai makes that auditor can be
any person working in the company , for example bodyguards, the production
staff, the accounting, personnel and head office. This is possible thanks to a
very simple design of the sheet audit. The sheet contains the most common check
list of areas to check in the form of pictures and images along with the
location of the place on the map layout.
Conclusion
In the literature, there are different views and descriptions of the
various tools of Lean Manufacturing. This paper aims to bring all the tools and
methods LM, starting from the general 5S, and ending with the less well-known:
Hoshin kanri, leveling production.
Each of the methods of Lean Manufacturing is designed to support the
company the elimination of waste occurring on the production and in achieving
the objectives of improving production. Table 1 is presented a summary of eight
types of waste, and sample tools to help eliminate them.
Table 1. Summary of types of waste and methods of
Lean Manufacturing, which help eliminate them,
Waste
|
Methods of Lean
Manufacturing
|
Overproduction
|
Kanban,
Heijunka, VSM
|
Excessive
stocks
|
Kanban,
Heijunka, VSM
|
Mistakes and
defects in the quality of products
|
Poka-Yoke,
Jidoka, Kamishibai
|
Unnecessary
movement
|
5S,
Standardized work
|
Unnecessary
transport
|
Kanban
|
Waiting
|
TPM, SMED
|
Excessive
processing
|
Standardized
work, Kanban
|
Untapped
potential employee
|
Kaizen
|
The article tools and methods of Lean Manufacturing is only a small
fraction of all the available literature on methods of improving production.
The Polish companies have only recently started to use the basic tools, such
as. 5S or SMED. However, over time the company will begin to implement newer
methods LM.
Anknowledgment
The presented results of the research, carried
out under the theme No. 02/23/DSMK/7677, was funded with a grant to science
granted by the Ministry of Science and Higher Education.
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