p–ISSN: 2723 – 6609 e-ISSN: 2745-5254
Vol. 5, No. 12, December 2024 http://jist.publikasiindonesia.id/

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 6177

CFD Application to Eliminate Delamination Defects in
Flange Products

Aep Supriatna

Institut Sains dan Teknologi Nasional (ISTN), Indonesia
Email: [email protected]

*Correspondence
ABSTRACT

Keywords: air trap; CFD;
defect; delamination;
foreign material.

Delamination defects in the breather pipe of flange products
produced through the injection molding process are a critical
issue that affects product performance. The objective of this
study is to reduce the detected delamination rate by 3.77%
from a total of 2173 production units, with a maximum
allowable limit of 0.5%. The method applied includes
identifying the cause of delamination through analysis by
collecting defect data, analyzing through the CFD
(Computation fluid dynamic) method, and observing mold
conditions. The proposed solution focuses on improving the
slider motion mechanism of the mold and adding a gas vent
with a vacuum system. Test results showed that these
improvements succeeded in reducing the delamination rate
to 0%. Further evaluation through X-ray analysis and
microscopic checking confirmed no significant voids in the
breather pipe and the integrity between material layers. The
conclusion of this study confirms that foreign material, in the
form of plastic debris and gas burn deposit injected due to
slider mechanism failure and lack of gas vent, is the main
factor causing delamination. This study is expected to
provide comprehensive guidance for the industry in
addressing similar issues in the future.

Introduction

Injection molding or plastic injection is the most commonly used method of the
product manufacturing process in producing plastic products by molding. Many plastic
products are produced from this method (Myers, Mulyana, Castro, & Hoffman, 2023).
From simple products such as plastic cups, mobile phone casings, and children's toys to
complex products such as dashboards, fuel pump flanges, four-wheeled modules such as
(cars) and two-wheelers (motorcycles), and aircraft components. The results of the
injection molding process are almost always used in daily activities (Yilmaz, Yang, &
Turng, 2019). The machine used for the injection molding process is called a plastic
injection machine. The injection molding process requires a plastic mold. Mold is a tool
used to shape a product according to the design we want (shape and dimensions). Mold
is formed from two main parts, namely cavity and core (Wang, Wang, & Chen, 2022).

Aep Supriatna

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 6178

The two are an inseparable unit, because the combination of the core and cavity will
form the components that form the product (Iswanto, Rambe, Jabbar, & Ginting, 2013).
The number of product formers in a plastic injection mold is called the number of cavities.
A mold that has 2 cavities means that the mold can produce 2 products in each shot (every
1 process cycle) (Badarisman, Hamid, Ideris, Bakar, & Jalar, 2022).

Flange is an important component of FPM (Fuel pump module) or fuel pump
module on 4-wheeled vehicles which is produced through a plastic injection process using
a hot runner system mold and a 220t tonnage vertical injection engine (Ghorpade &
Shinde, 2022). The flange serves as a link between the inside and outside of the fuel tank.
In the initial stage of flange production, delamination defects were found in the breather
pipe that did not appear continuously, but the percentage of defects that occurred was
3.77% of the total production of 2173 units, this was not by the target that had been set,
which was a maximum of 0.5% (Permana, Topan, & Anwar, 2021). Research is needed
to analyze the causes of delamination defects that do not appear continuously and
comprehensive corrective measures to reduce and even eliminate the problem of
delamination production defects in the breather pipe part of Flange products (Prasad,
2021).

Table 1 Flange Production Data
Day 1 2 3 4 5 6 Total

Production
(units)

444 472 470 183 159 445 2173

Defects
(units)

15 14 10 3 17 23 82

Defects
(%)

3.38 2.97 2.13 1.64 10.69 5.17 3.77

According to Prasad in Rex journal volume 9, Issue-5 (2021:14) states that

delamination is a mold defect that occurs when a thin layer on the surface of a printed
part quickly separates or peels off from its base material, in other words as a peeling
surface layer defect. The most common causative factor that results in delamination is the
penetration of foreign materials into plastic materials. When two materials cannot bond
to each other well then there will be separation of layers (Katkhede, Raut, & Labade,
2017).

According to A.H Badarisman, K, Abdul Hamid, H.Ideris, M.Abu Bakar, A.Jafar
(2022: 6) stated that molding temperature is the highest effect of the delamination
problem on SOT packages.

CFD Application to Eliminate Delamination Defects in Flange Products

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 6179

Method
Identify the problem

The problem of delamination defects that occur in the breather pipe part of flange
products is researched how it can occur continuously, what are the main causes and what
kind of improvement steps are appropriate to overcome the delamination problem.

Figure 1
Delamination defects in breather pipe flange products

Literature Studies and Research Reviews

Literature studies and previous research reviews were conducted to build a strong
knowledge base and compare different research methods that have been used to address
similar problems and determine the most effective methods. By doing this, it is hoped that
the limitations of previous research can be understood so that they can be avoided or
improved in new research.
Data collection

Production data is collected to obtain facts about the number and percentage of
delamination defects from the number of flange units that have been produced.
Specifications of materials, machines, molds, and test equipment to be used are also
collected for study.
Data processing
Material

Flange products use POM (polyoxymethylene) material from polyplastic
manufacturers with duration type M90-44. The general characteristics of this material are
shown in Table 2.

Aep Supriatna

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 6180

Table 2
General Characteristics of POM Duracon M90-44

Injection Machine and Setting Parameters

The injection machine used is JSW JT 220 RAD 410V series with a screw diameter
of 46mm, a maximum injection pressure of 239 Mpa, and an injection volume of 207 cm3

with setting parameters shown in table 3.
Table 3

Process setting parameters

CFD Analysis

Computational Fluid Dynamics (CFD) allows visualization of material flow in the
mold, helps identify areas with poor or uneven flow, and looks at temperature and

Parameter setting Value

Stroke 116.5 mm

Injection Speed 10-40-15-40 mm/s

Cooling time 13.0 s

Hold Pressure [ waktu] 55 Mpa [20 s]

RPM 110 min
-1

Back Pressure 8.0 Mpa

Barrel Temperature 190-195-190-180
o
C

Mold Tempearature 45
o

CFD Application to Eliminate Delamination Defects in Flange Products

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 6181

pressure distributions as well as the uniformity conditions of the frozen layer to identify
delamination in the breather pipe part of flanged products. Estimation of the filling time
needed to information on the confidence of filling / confidence in product quality that will
occur from the setting parameters used can also be done. By using CFD, many expensive
and time-consuming physical experiments can be replaced by fast and efficient
simulations.

Results and Discussion
CFD analysis results

Figure 2
Fill time analysis

Filling the plastic resin into the mold, takes 4.87 seconds.

Gambar 3
Analysis Confident of fill

Based on the setting parameters used, the confidence of filling is 99.3%.

Aep Supriatna

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 6182

Figure 4
Pressure drop analysis

The pressure drop that occurred was 44.09 Mpa.

Figure 5
Temperature uniformity analysis

The average temperature is 216.2oC, but in the breather pipe area, there is a large

enough temperature difference so there is the potential for delamination due to the lack
of integrity between layers.

Figure 6
Frozen Layer Analysis

In the breather pipe area, there is a difference in the frozen layer on 1 surface.

Breather
Pipe

Air trap on
breather pipe

CFD Application to Eliminate Delamination Defects in Flange Products

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 6183

Figure 7

Analysis of Water Traps / trapped air

Air traps occur in the breather pipe area, this has the potential to cause voids due to

gases that cannot get out of the mold.
From the results of the CFD analysis, it can be seen that although the confidence of

fill is very good (99.3%), in the breather pipe area there are potential problems due to the
occurrence of temperature inhomogeneity, frozen layer, and the presence of air traps. The
pressure drop value that occurs (44.09 Mpa) and the filling time required (4.87 seconds)
are still below the actual value of the setting parameters on the injection machine so it is
still considered safe and proven by the weight stability of the product.

Figure 9 Weight Stability of Flange Products

Plastic debris appear due to a thin flash in the parting line area near the gate that is
easy to come off. The plastic debris that are sticky are also affected by the new resin
material.

Figure 10

Thin Flash occurs on the parting line due to the failure of the slider core part

Ensuring the source of plastic debris from the cylinder injection process and hot

runner is carried out by checking the high speed camera through the mold purging
method.

Thin
Flash

Min 204 gr

Max 208 gr

Setting parameter used :
Screw metering (SM) = 105 mm
Velocity (V) = 10 mm/s

Aep Supriatna

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 6184

Figure 11
Checking foreign materials with a high speed camera

The results of the examination are as follows:

Figure 12

Results of checking foreign materials with high speed camera

From the results of checking the high camera, there was no foreign material ,
bubbles or delamination. Failure mechanism on core scratch slider and gas burn
problem:

High Speed camera position

CFD Application to Eliminate Delamination Defects in Flange Products

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 6185

Figure 13

Mold Mechanism when full close

Solution:
1. Eliminates thin flashes that easily fall off with the repair of the slider core to normal

conditions.
2. Modification of cylinder rod to provide clearance of 0.5 mm.
3. The addition of gas vents in the slider area with a vacuum system to eliminate air traps

as the cause of gas burn.

CFD Application to Eliminate Delamination Defects in Flange Products

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 6187

Figure 15

Addition of a gas vent to the slider core with a vacuum system

6430

3273

1949

0,95%

0,40%

0,00%
0,00%

0,10%

0,20%

0,30%

0,40%

0,50%

0,60%

0,70%

0,80%

0,90%

1,00%

1000

2000

3000

4000

5000

6000

7000

Cylinder rod and
flash repair

Gasvent without
vacuum

Gasvent with vaccum

Production quantity VS % Delamination defect

Total Produksi NG %

pcs %

Aep Supriatna

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 6188

Figure 16
Graph 2 Production Data after 3 stages of improvement

A 100% visual inspection is carried out to check the delamination throughout the

production process. X-ray and microscopic /SEM testing is also carried out to ensure that
there are no significant voids in the breather pipe and that the integrity between the layers
of the material is maintained.

Figure 16

Void inspection by X-ray
There is no void in the breather pipe area

Area
breather
pipe

CFD Application to Eliminate Delamination Defects in Flange Products

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 6189

Figure 17
Integration inspection between layers of the inside of the breather pipe with SEM

50x magnification

Figure 18
Inspection of the integration between layers of the inside of the breather pipe with

SEM magnification 104x

Figure 19
Inspection of the surface of the breather pipe in areas where delamination often occurred

in the past with SEM magnification 104x.

Aep Supriatna

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 6190

In the SEM results, no voids were found, the integration between the layers was
good and no delamination was obtained.

Conclusion

CFD analysis is very helpful in identifying the cause of delamination through the
simulation of fluid flow and the distribution of temperature and pressure into the mold
so that areas with high interlaminar stress due to high temperature differences can be
identified. The main cause of delamination in the breather pipe part of flange products is
foreign materials/foreign objects, both in the form of plastic debris and dirt/gas burn
deposits. From the production results after 3 stages of improvement, the percentage of
delamination decreased from 3.77% to 0%. The results of x-ray and microscopic/SEM
tests showed that there were no void problems due to air traps or integration between
layers. Periodic maintenance of the mold and cleaning of the gas vent area and gas deposit
trap on the slider core must be done regularly and periodically so that the problem of
delamination does not reappear in the future.

CFD Application to Eliminate Delamination Defects in Flange Products

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 6191

Bibliography

Badarisman, A. H., Hamid, K. Abdul, Ideris, H., Bakar, M. Abu, & Jalar, A. (2022).
Effects of molding temperature on delamination of small outline transistor (SOT).
Journal of Physics: Conference Series, 2169(1), 12035. IOP Publishing.

Ghorpade, Kabirdas B., & Shinde, Sharda M. (2022). Glass Delamination in sterile
formulations and Drug Recalls: A Review. International Journal of
Pharmaceutical Sciences and Developmental Research, 8(1), 1–5.

Iswanto, Adi, Rambe, M., Jabbar, A., & Ginting, Elisabeth. (2013). Aplikasi metode
Taguchi Analysis dan failure mode and effect analysis (fmea) untuk perbaikan
kualitas produk di PT. XYZ. Jurnal Teknik Industri USU, 2(2), 219330.

Katkhede, Rahul R., Raut, Abhijeet A., & Labade, Kalyan. (2017). Defects and Solution
of Plastic Parts during Injection Mouding. International Journal for Scientific
Research & Development, 5(09), 436–439.

Myers, Mason, Mulyana, Rachmat, Castro, Jose M., & Hoffman, Ben. (2023).
Experimental Development of an Injection Molding Process Window. Polymers,
15(15), 3207.

Permana, Henry, Topan, Topan, & Anwar, Syahrul. (2021). Produksi Proses Komponen
Plastik Flip Flop Dengan Mesin Injeksi Molding Type Hidrolik. Jurnal Baut Dan
Manufaktur: Jurnal Keilmuan Teknik Mesin Dan Teknik Industri, 3(02), 8–17.

Prasad, P. Durga Ravi. (2021). Analyzation Of Various Local Surface Defects In
Injection Moulding Process. REX-ISSN 2321-1067, 9.

Wang, Rong Tsu, Wang, Jung Chang, & Chen, Sih Li. (2022). Investigations on
Temperatures of the Flat Insert Mold Cavity using VCRHCS with CFD Simulation.
Polymers, 14(15), 3181.

Yilmaz, Galip, Yang, Huaguang, & Turng, Lih‐Sheng. (2019). Injection molding of
delamination‐free ultra‐high‐molecular‐weight polyethylene. Polymer Engineering
& Science, 59(11), 2313–2322.