How to cite:
Dian Putrawangsa, Agustinus Caniago, Samuel Aprilio, Thedy
Yogasara. (2022). Application of PDCA Method in Improving the
Quality of Valve Production. Journal Eduvest. Vol 2(8): 1.573-1.586
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Eduvest Journal of Universal Studies
Volume 2 Number 8, August, 2022
p-ISSN 2775-3735-e-ISSN 2775-3727
APPLICATION OF PDCA METHOD IN IMPROVING THE
QUALITY OF VALVE PRODUCTION
Dian Putrawangsa
1
, Agustinus Caniago
2
, Samuel Aprilio
3
, Thedy Yogasara
4
Faculty of Industrial Technology, Parahyangan Catholic University
1,2,3,4
Email: [email protected]
1
, [email protected]
2
,
[email protected]
3
, [email protected]
ABSTRACT
Plastic is one of the most widely used raw materials for a
product. Human life cannot be separated from products or
equipment made from plastic. Company X often has problems
with the quality of the products produced, especially valve
products as products that are produced every day. The
corrective step used to assist Company X in improving the
quality of valve products is the application of the PDCA
method. PDCA method consists of the plan, do, check, and act
stages. The proposed improvement design was carried out
based on the results of data processing and obtained as many
as 9 proposed improvements. In the do stage, implementation
of the proposed improvements that have been designed is
carried out, five proposed improvements can be implemented
and the other four in the form of recommendations. Next is the
check stage, which is the process of collecting data again on
the results of the implementation of the proposed
improvement. Based on the results of the check stage, a
standardization process was carried out at the act stage to
improve the performance of the proposed improvement and
the quality of the valve product. Standardization is done by
changing or improving the proposed improvements that have
been implemented. Research has succeeded in reducing the
number of defective valve products with the proportion of
defects that were previously 1.16% to 0.57%.
KEYWORDS
Total Quality Management, PDCA, Plastic, Improvement
Dian Putrawangsa, Agustinus Caniago, Samuel Aprilio, Thedy Yogasara
Application of PDCA Method in Improving the Quality of Valve Production 1.574
This work is licensed under a Creative Commons
Attribution-ShareAlike 4.0 International
INTRODUCTION
In general, plastic is used as the basic material for a product that is used in everyday
life. The plastics used have basic materials or materials that vary greatly in terms of
characteristics, properties, and functions. Examples of these plastic base materials are
Polyethylene (PE), Polypropylene (PP), Polyvinyl chloride (PVC), and many others. The
use of these plastic base materials can be adapted to the products that will be used in
everyday life. In addition, plastics have flexible properties so they can be a special solution
that can be considered to meet needs in limitless products, applications, and sectors.
Human life cannot be separated from products or equipment that support daily life,
especially products made of plastic. According to Schmaltz et al. (2020), the use of plastic
has increased sharply because of its benefits in various fields. Along with the times, the use
of plastic is increasing so plastic companies are increasingly advancing in the process of
producing plastic-based equipment. The higher the level of plastic use in the world, the
higher the level of plastic production in the world. This is by the high demand which causes
the supply (supply) to be higher as well.
Plastics Europe (2021) explains that the world's plastic production in 2020 has
reached 367 million tons produced for various types of products used by various groups of
people. Asia itself has contributed to plastic production of around 52% of global plastic
production, one of which was contributed by Indonesia (Plastics Europe, 2021). Plastic
production in parts of the world is expected to continue to increase from year to year. Of
course, this is a good opportunity for plastic companies in the world. Plastic companies can
be referred to as manufacturing companies, where companies carry out the production
process from raw materials, and semi-finished goods, to certain finished goods. Company
X is a company engaged in the production of plastic products, such as household appliances
and other daily necessities. In producing a product, of course, a company has a production
target that is useful to meet the level of demand and customer satisfaction.
Of the various plastic molding methods, injection molding is a prevalent method
to apply. According to Lee et al. (2022), injection molding is a method of making plastic
products by injecting hot plastic melt through the cavity into the mold, the plastic melt
follows the shape of the mold and undergoes cooling to become a finished product. This
plastic injection process is carried out in three stages, namely charging, pressing, and
holding with the help of piston pressure during these processes (Alonso-González, Felix,
& Romero, 2022; Lee et al., 2022).
A company has problems to deal with. If there is no improvement or development,
then the problem can hamper the existing processes within the company, both in terms of
meeting daily targets or target consumers that have been determined. In the implementation
of the company's production process, various problems can be found and one of them is the
poor production process. Problems in the production process have an impact on other
processes in the company so it is considered very disturbing because it affects the delivery
of finished goods to consumers and the accuracy of completing existing orders. Therefore,
the products produced by the company must comply with existing standards and
specifications to be accepted by consumers during the marketing process. This is also like
what is happening in industries in the world that want to achieve improved performance
and product quality to achieve profitability, sustainability, market share, and competition
with competitors (Costa, Lopes, & Brito, 2019; Daniyan, Adeodu, Mpofu, Maladzhi, &
Kana-Kana Katumba, 2022)
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Several general problems have been identified in Company X. These problems
were collected before further research was carried out, which are as follows:
1. Excessive number of defects in the product.
The observations made were to observe the production of plastic products in
Company X and it was found that defective products were often produced. There are many
defective products for each type of product produced by an injection molding machine.
Defects that often occur are flashing, short mold, black dot, splay, and many others.
2. There is no display of information about the condition of the machine during the
production process.
PPIC, Materials, QC, and other parties who need to know the condition of the
machine, the products produced, and other necessary information must always come to the
production site of each machine and ask the operator who works on the machine for the
required information.
3. Layout of machines and supporting facilities that are not neat.
Based on the observations made, the placement of machines and equipment on the
production floor is very irregular. The production floor is often blocked by packaging or
storage of finished goods so that it interferes with travel on the production floor.
4. Inventory of raw materials and finished goods is often insufficient.
Observations were made at the raw material storage warehouse and it was found
that the company ran out of raw materials to produce one of the products which caused the
company to have to wait for additional raw materials to arrive, so additional time was
needed to be able to fulfill consumer orders.
5. Personal Protective Equipment (PPE) is not completely available.
The company only provides gloves at the start of work. Meanwhile, other
protective equipments, such as masks and earplugs are not provided by the company.
6. Lack of communication between each division.
In the communication flow that exists on the production floor, information is still
managed manually and independently so that any data needed in a particular division must
be asked directly to the relevant division.
After identifying several problems that occur in Company X, the next stage is to
choose one problem that has the highest priority compared to other problems. Based on the
selection of priority problems, the problem that is the subject of research is the problem of
defects in the product in an excessive number of defects in the product. Based on the the
proportion of defective products from Company X, it was found that valve products have
the highest proportion of defective products, which is 1.53% compared to other products.
RESEARCH METHOD
This research uses quantitative research methods by applying the tools and analytical
methods included in the selected method. Several methods can be used to reduce defects in
the production process. The methods in question are the PDCA method (Tague, 2005) and
Six Sigma DMAIC (Webber & Wallace, 2007). PDCA is a method to improve product
quality by implementing the plan, do, check, and act processes. (Tague, 2005). The Six
Sigma DMAIC method is a method that can also be used to make process improvements
so that defective products can be reduced (Webber & Wallace, 2007). However, of the two
methods, the PDCA method was chosen because the time difference in PDCA
implementation was less than the DMAIC method considering the time limitations of the
study. PDCA offers significant advantages for attracting stakeholders, quickly verifying
concepts, and generating new improvement ideas (Rajagopalan, 2020; Raza, Malik, &
Bilberg, 2021).
Dian Putrawangsa, Agustinus Caniago, Samuel Aprilio, Thedy Yogasara
Application of PDCA Method in Improving the Quality of Valve Production 1.576
The plan stage in PDCA includes the define, measure, and analyze stages in DMAIC,
thus indicating that PDCA requires a more concise implementation stage than DMAIC.
However, in its implementation, the PDCA cycle is still carried out in the same way as
DMAIC (Scheller, Sousa-Zomer, & Cauchick-Miguel, 2021).
RESULT AND DISCUSSION
The research will enter the implementation of the stages in PDCA, which is as
follows:
A. Plan
The research was conducted by collecting data on the number of defective valve
products and the types of defects during the period of practical work carried out. The step
after data collection is done is to process it into the form of a control chart or control chart.
The purpose of making this control chart is to become a comparison performance parameter
between the production results before the proposed improvement is implemented and after
the improvement proposal is implemented. The data obtained during the data collection
process is attribute data. Table 1 is a recapitulation of the calculation of the LCL, CL, and
UCL proportion values for all replications after deletion of OOC (out of control) events.
Table 1. p-Chart of Valve Products in Current Condition
No
Defective Product (Unit)
LCL
CL
UCL
1
263
0,0128
0,0093
0,0116
0,0138
2
326
0,0134
0,0095
0,0116
0,0136
3
300
0,0123
0,0095
0,0116
0,0136
4
301
0,0128
0,0095
0,0116
0,0137
5
323
0,0129
0,0096
0,0116
0,0136
6
303
0,0124
0,0095
0,0116
0,0136
7
241
0,0107
0,0095
0,0116
0,0137
8
254
0,0122
0,0094
0,0116
0,0138
9
208
0,0083
0,0096
0,0116
0,0136
10
309
0,0126
0,0095
0,0116
0,0136
11
285
0,0108
0,0096
0,0116
0,0136
12
221
0,0113
0,0093
0,0116
0,0139
13
293
0,0111
0,0096
0,0116
0,0136
14
221
0,0099
0,0094
0,0116
0,0137
15
280
0,0115
0,0095
0,0116
0,0136
16
265
0,0117
0,0095
0,0116
0,0137
17
281
0,0124
0,0095
0,0116
0,0137
18
156
0,0079
0,0093
0,0116
0,0139
19
110
0,0058
0,0093
0,0116
0,0139
20
216
0,0129
0,0091
0,0116
0,0141
21
147
0,0070
0,0094
0,0116
0,0138
22
157
0,0125
0,0087
0,0116
0,0145
23
165
0,0134
0,0087
0,0116
0,0145
24
167
0,0109
0,0090
0,0116
0,0142
25
184
0,0144
0,0087
0,0116
0,0144
26
211
0,0138
0,0090
0,0116
0,0142
27
162
0,0119
0,0088
0,0116
0,0143
28
214
0,0140
0,0090
0,0116
0,0142
29
171
0,0132
0,0088
0,0116
0,0144
30
171
0,0117
0,0089
0,0116
0,0142
31
189
0,0123
0,0090
0,0116
0,0142
32
151
0,0111
0,0088
0,0116
0,0143
33
160
0,0113
0,0089
0,0116
0,0143
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34
179
0,0130
0,0088
0,0116
0,0143
35
210
0,0141
0,0090
0,0116
0,0142
TOTAL
7.794
The next step after calculating all the new proportion values, CL, UCL, and LCL
is making a control chart as a visualization of the calculation. Figure 1 is the p-chart on the
valve product.
Figure 1. p-Chart for Valve Product in Current Condition
Next, a Pareto diagram is designed to identify which types of defects are the most
common or most common for valve products. Figure 2 is a Pareto diagram for the types of
defects in valve products. Based on Figure 2, short mold, flashing, and black dot defects
are the most common types of defects, so they were chosen to be the focus of improvement
in the research. For this research, short mold was chosen as the type of defect that would
be more focused to be improved. Examples of short mold defects in valve products can be
seen in Figure 3.
Figure 2. Pareto Diagram of Valve Products in Current Condition
343128252219161310741
0.0150
0.0125
0.0100
0.0075
0.0050
Sample
Proportion
_
P= 0.01159
UCL=0.01422
LCL=0.00895
1
1
1
1
Tests performed with unequal sample sizes
P Chart of Jumlah Produk Cacat
36.69%
58.79%
77.26%
95.38%
98.67%
99.51%
100.00%
0.00%
10.00%
20.00%
30.00%
40.00%
50.00%
60.00%
70.00%
80.00%
90.00%
100.00%
0
1000
2000
3000
4000
5000
6000
7000
8000
Short
Mold
Flashing Black
Dot
Bubble Splay Sink
Mark
Warping
Defective Product (Unit)
Defect Type
Dian Putrawangsa, Agustinus Caniago, Samuel Aprilio, Thedy Yogasara
Application of PDCA Method in Improving the Quality of Valve Production 1.578
The root causes of the short mold defects were found along with proposed
improvements based on the root causes of the existing problems. Proposed improvements
for each root cause can be the same if the root causes are interconnected. Table 2 is a
proposed improvement for each existing root cause.
Table 2. Proposed Solution of Short Mold Defects in Valve Products
No
Cause of Defective
Suggestions for Improvement
1
Newly employed operators
Provide training that contains counseling,
direction, and guidance regarding the plastic
production process using an injection molding
machine
2
Buttons and displays on machines using
foreign languages that are difficult to
understand
Create a visual display on the injection molding
machine button
3
There is no SOP for engine calibration
Creating SOPs about injection molding machine
calibration
4
The use of an old machine
Perform regular maintenance of the old injection
molding machine
5
The mold locking system is not
functioning properly
Make a visual display for mold locking on the
injection molding machine
6
Nozzle is not cleaned regularly
Making SOPs for nozzle cleaning on injection
molding machines
7
The material sack is not closed
Practicing the habit of closing the sack of material
before and after use using a sack binding aid
8
There is no fixed place to store material
for production
Provide direction to the operator to always
directly use the material from the material sacks
that have been opened so that they are neatly
arranged and clean
9
The operator forgot to find a cover to close
the hopper
Make SOPs and Visual Display regarding the
closing of the hopper on the injection molding
machine
Based on Table 2, the following are ten improvements that can be described to
overcome the short mold defects of valve products.
Figure 2. Comparison of Valve Product: Good Quality (A) and Short Mold (B)
1. Newly employed operators
The proposed solution is given in the form of providing training that contains
counseling, direction, and guidance regarding the process, way of working, and how to
overcome defects in the plastic production process using an injection molding machine.
The aim is to make new operators can understand how to prevent and overcome the defects
that occurs in the product produced. The following is a procedure for carrying out training
for new operators:
B
A
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a. The training is conducted in the first shift (07.00 to 15.00) on Saturday when
there are new operators who want to work. Therefore, it is very possible that
orders have been fulfilled or production needs have decreased so that
permanent operators or those who have worked in the company for a long time
can assist the company in training new operators.
b. The training was carried out by bringing new operators around the production
floor and trying to operate the machine with the help and guidance of the
permanent operator.
c. New operators are explained about the possibilities of frequent engine damage
and how to prevent or overcome them precisely and quickly.
d. The new operator is explained about the type of defect in the product that
occurs during the production process and how to identify and overcome the
possibility of the defect again.
2. Buttons and displays on machines using foreign languages that are difficult to
understand
A visual display is needed to overcome this. One of them is making a sticker for
the engine operating instruction button using Indonesian. Making a visual display in the
form of a sticker for the injection molding machine button follows the size of the button
that already exists on the machine. Figure 3 is the example of visual display used on
egnine’s buttons.
Figure 3. Proposed Solution for Visual Display on the Button
3. There is no SOP for engine calibration
The proposed improvement that can be designed is to create an SOP (Standard
Operating Procedure) regarding the machine setup process carried out at the beginning of
the production week or every time the machine is needed a setup process.
4. The use of an old machine
The proposed improvement that can be designed is to carry out regular
maintenance of the injection molding machine to prevent the occurrence of a sudden
broken-down, and other things.
5. The mold locking system is not functioning properly
The corrective step that needs to be done is making a visual display that is useful
to remind the operator to always make sure the mold lock is functioning and locked
Current
Condition
Proposed
Solution
Dian Putrawangsa, Agustinus Caniago, Samuel Aprilio, Thedy Yogasara
Application of PDCA Method in Improving the Quality of Valve Production 1.580
properly. The following is a calculation for determining the font size on the print lock visual
display and an example of the visual display.
Snellen acuity (S) = 20
Distance from eyes to object (D) = 900 mm
Ratio (R) =
Letter thickness (Ws) = 1,45 × 10
-5
× 20 × 900
= 0,261 mm
Letter height (H
L
) =

= 2,088 mm
Letter width (W)
=
× 2,088
= 1,2528 mm
Distance between letters =
× 2,088
= 0,522 mm
Distance between words =
× 2,088
= 1,392 mm
Distance between lines and sentences =
× 2,088
= 1,392 mm
The following is a visual display for locking the mold on an injection molding
machine with a paper size of 290 x 90 mm.
Figure 4. Proposed Visual Display for Mold Locking System
6. Nozzle is not cleaned regularly
Proposed improvements that can be made to overcome these causes are to create
and design an SOP that discusses the obligations in the process of checking the readiness
of the machine before the injection molding machine is used. In addition, it can also contain
the injection molding machine maintenance process, especially on the nozzle part properly
and correctly regularly.
7. The material sack is not closed
Proposed improvements that can be made are to establish good habits by closing
the sacks of materials or raw materials needed before and after use. The suggestion given
was also in the form of providing an alternative sack cover in the form of a rope. The
purpose of the sack cover is to maintain and guarantee the quality of the raw materials in
the sacks even though they are already open so that it is more likely that dirt or foreign
components will enter the sacks of the materials used.
8. There is no fixed place to store material for production
The proposed improvement given is to direct the operator to always immediately
use raw materials or materials from material sacks that have been opened so that they are
not scattered and do not become mixed with other materials. In addition, operators who
still need material sacks are advised to place the material sacks in the corner of the
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production floor room so as not to interfere with the material handling process or operator
movement on the production floor.
9. The operator forgot to find a cover to close the hopper
Proposed improvements that can be made to the root of the problem are making
SOPs for hopper closures so that operators always follow these directions. This hopper
closing SOP is made and combined with other SOPs in the same place so that operators
who want to carry out production activities on the machine concerned can immediately
read all existing SOPs because they are placed in the same place and easy to pick up. In
addition, it is necessary to have a visual display that is easily seen by the operator to close
the hopper before and after use. The following is an example of a visual display measuring
290 x 80 mm for the closure of the hopper based on calculations that have been carried out
previously, which is the same as forming a visual display for locking molds or molds on an
injection molding machine.
Figure 5. Proposed Visual Display for Closing the Hopper
B. Do
After planning improvements, then the next process is the implementation or
application of the proposed improvements that have been made in the plan section of the
production process. Proposed improvements to be implemented are the application of SOPs
to properly carry out the machine setup process, SOPs and visual displays for hopper
closures, visual displays for locking molds or molds, and suggestions for repairing sack
binders to overcome open material sacks. Figure 6 is the implementation of the SOP
installation of the setup process on the injection molding machine for valve production at
Company X.
Figure 6. SOP Implementation Machine Setup Process
A visual display for closing the hopper is mounted on the neck of the hopper so
that the operator always remembers to close the hopper when in use or not when in use.
The following is an implementation of the installation of a visual display for closing the
hopper on an injection molding machine.
Dian Putrawangsa, Agustinus Caniago, Samuel Aprilio, Thedy Yogasara
Application of PDCA Method in Improving the Quality of Valve Production 1.582
Figure 7. Hopper Closing Visual Display Implementation
The mold locking visual display is mounted on the cover glass of the injection
molding machine so that the operator always remembers to check the condition of the mold
when it is used or when trying to set up the machine. Figure 8 is an implementation of a
mold locking visual display mounted on the cover glass of an injection molding machine.
Figure 8. Mold Locking System Visual Display Implementation
The final improvement proposal that was implemented was the process of tying
sacks as anticipation to overcome the root cause of the problem of open material sacks
which could cause dirt or dust to enter the mixed material sack. The proposed improvement
is to provide raffia rope as a tool to bind and cover material sacks. Figure 9 is a comparison
of the current condition of the material sacks with the proposed improvements that have
been applied to Company X.
Figure 9. Sack Binding Implementation
In addition to the proposed improvements that have been implemented as described
previously, there are suggestions for improvements that become recommendations and are
only submitted directly to the company manager.
Before
After
Before
After
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C. Check
After the implementation stage or the implementation of the proposed
improvements made to the company, an examination will be carried out on the condition
of the production process at Company X in producing valve products. The check process
is carried out by re-observing the valve product production process after the proposed
improvement has been applied for a certain period to find out whether the proposed
improvement is indeed effective or not. After making observations to get new data, the next
step is making a new control chart to show the changes. The check stage is also carried out
on proposed improvements in the form of recommendations only, namely by verifying the
company represented by the company manager.
The new control chart was designed based on 17 new data taken during the period
of re-observation at the company after the recommendations for improvement were
implemented. Table 3 is a recapitulation of the calculation of proportion, CL, UCL, and
LCL for all data.
Table 3. p-Chart of Valve Products After Improvements
No
Defective Product (Unit)
LCL
CL
UCL
1
68
0,0044
0,0039
0,0057
0,0075
2
78
0,0047
0,0040
0,0057
0,0075
3
93
0,0064
0,0038
0,0057
0,0076
4
68
0,0054
0,0037
0,0057
0,0077
5
105
0,0070
0,0039
0,0057
0,0076
6
53
0,0038
0,0038
0,0057
0,0076
7
75
0,0058
0,0037
0,0057
0,0077
8
76
0,0063
0,0037
0,0057
0,0078
9
108
0,0075
0,0038
0,0057
0,0076
10
88
0,0056
0,0039
0,0057
0,0075
11
76
0,0047
0,0039
0,0057
0,0075
12
88
0,0056
0,0039
0,0057
0,0075
13
97
0,0068
0,0038
0,0057
0,0076
14
112
0,0068
0,0040
0,0057
0,0075
15
86
0,0063
0,0038
0,0057
0,0076
16
90
0,0063
0,0038
0,0057
0,0076
17
51
0,0039
0,0037
0,0057
0,0077
TOTAL
1.412
After obtaining all the values needed for each data, the next step is to create a control
chart. Figure 10 is a p-chart produced with the help of the MINITAB program. Based on
Figure 10, it can be seen that there are no processes outside the UCL and LCL limits, it can
be concluded that all processes on the control chart are already in control condition, so
there is no need for a revision process on the control chart. After the formation of a control
chart for production results after the implementation of the proposed improvement, a
comparison of the results with the current condition or before the proposed improvement
is carried out.
Dian Putrawangsa, Agustinus Caniago, Samuel Aprilio, Thedy Yogasara
Application of PDCA Method in Improving the Quality of Valve Production 1.584
Figure 10. p-Chart for Valve Product After Improvements
Table 4 is a comparison of the control chart of the valve production results. Based
on Table 4 it can be seen that the values of CL, UCL, and LCL generated on the p-Chart
after the proposed improvement on the valve product production process are smaller or
decreased compared to the current condition or before the proposed improvement was
implemented, so it can be said that the proposed improvement that has been implemented
have been effective in reducing the number of defective products produced and improving
the quality of the resulting valve products. This shows that the implementation of proposed
improvements to overcome the types of short mold, flashing, and black dot defects have
succeeded in reducing the proportion of defective valve products as a whole. The
percentage of defective products as a whole has decreased compared to those in the current
condition or before the repair, which is 0.57% compared to 1.16%. In addition, this
decrease has also succeeded in bringing valve products to the target desired by the
company, which is to produce a proportion of defective products that are below 1% as the
maximum limit for the proportion of defective products desired by the company.
Table 4. Control Chart Comparison of Valve Production Results
Comparison
Before Improvements
After Improvements
CL = 0,0116
UCL = 0,0140
LCL = 0,0092
CL = 0,0057
UCL = 0,0076
LCL = 0,0038
1715131197531
0.008
0.007
0.006
0.005
0.004
Sample
Proportion
_
P=0.005716
UCL=0.007701
LCL =0.003731
P Chart of Jumlah Produk Cacat_2
Tests performed with unequal sample sizes
1715131197531
0.008
0.007
0.006
0.005
0.004
Sample
Proportion
_
P=0.005716
UCL=0.007701
LCL=0.003731
P Chart of Jumlah Produk Cacat_2
Tests performed with unequal sample sizes
Eduvest –Journal of Universal Studies
Volume 2 Number 8, August 2022
1.585 http://eduvest.greenvest.co.id
D. Act
The last step is to carry out the act stage which is useful for carrying out adjustment
actions when needed. After the implementation process or implementation and examination
of the proposed improvements that have been applied to Company X, it can be seen that
quality problems that occur in valve products can be minimized, especially in the problem
of the number of defective valve products of short mold, flashing, and black dot types. In
addition to maintaining the proposed improvements that have been implemented, steps in
the act are also carried out by making improvements or developments from the proposed
improvements that have been implemented.
Table 5. Standardization of Implemented Improvements
No
Implemented
Improvements
Impact of Implementing
Improvements
Standardization
1
Installation of machine
setup process SOPs
Machines rarely undergo a re-
setup process in the middle of
the production process
Coating the SOP sheet with plastic
or laminate and fixing it all over
the injection molding machine
2
Hopper closing SOP
installation
Operators close the hopper
more often after loading the
material into the hopper
Coating the SOP sheet with plastic
or laminate and fixing it all over
the injection molding machine
3
Visual display installation
for hopper closing
Operators close the hopper
more often after loading the
material into the hopper
Covering the visual display
mounted on the hopper with plastic
4
Visual display installation
for mold locking system
Mold rarely loosens
Covering the visual display
mounted on the hopper with plastic
5
The use of binders on
material sacks
Material sacks are rarely
spilled and scattered
Replacing raffia rope as a material
sack binder with a clamp tool
CONCLUSION
Based on the research objectives that have been described in the introduction and the
data collection and processing process as well as the preparation of improvement proposals,
several conclusions can be drawn, namely, the types of defects in valve products that have
been identified in Company X are short mold defects, flashing, black dot, bubble, splay,
sink marks, and warping with the most defects occurring are short mold defects, flashing,
black dot. The causes of defects in valve products are newly employed operators, buttons
and displays on machines using foreign languages that are difficult to understand, there is
no SOP for engine calibration, the use of an old machine, the mold locking system is not
functioning properly, nozzle is not cleaned regularly, the material sack is not closed, there
is no fixed place to store material for production, the operator forgot to find a cover to close
the hopper.
Proposed improvements that can be given to Company X in reducing the number of
defective valve products are: provide training that contains counseling, direction, and
guidance regarding the plastic production process using an injection molding machine;
create a visual display on the injection molding machine button; creating SOPs about
injection molding machine calibration; perform regular maintenance of the old injection
molding machine; make a visual display for mold locking on the injection molding
machine; making SOPs for nozzle cleaning on injection molding machines; practicing the
habit of closing the sack of material before and after use using a sack binding aid; provide
direction to the operator to always directly use the material from the material sacks that
Dian Putrawangsa, Agustinus Caniago, Samuel Aprilio, Thedy Yogasara
Application of PDCA Method in Improving the Quality of Valve Production 1.586
have been opened so that they are neatly arranged and clean; make SOPs and Visual
Display regarding the closing of the hopper on the injection molding machine.
The number of defective valve products resulting from the proposed improvement
compared to the current condition effectively decreased with the percentage of the
proportion of defects produced being 0.57% compared to the previous 1.16%. The
proportion of defects in valve products is also below the maximum limit for defective
products tolerated by the company, which is below 1%.
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