Product Brochure

www.kepital.com
Product Brochure
CONTENTS
1.
1-1.
1-2.
1-3.
General information
KEPITAL Nomenclature
Characteristics of KEPITAL
Typical properties of KEPITAL
03
04
06
Physical and mechanical properties
Behavior under short-term stress
Stress-Strain curve
Temperature dependency on mechanical properties
Impact strength
Shear strength
Specific volume
Hardness
Poisson’s ratio
Behavior under long-term static stress
Property to cyclic stress
10
10
10
11
11
11
12
12
13
14
3.
3-1.
3-2.
3-3.
3-4.
3-5.
3-6.
Thermal properties
Melting point
Specific heat
Heat deflection temperature
Coefficient of linear thermal expansion
Thermal conductivity
Heat ageing
15
15
15
15
16
16
4.
4-1.
4-2.
4-3.
Tribological properties
Friction
Wear
PV Limits
17
17
17
5.
5-1.
5-2.
5-3.
5-4.
5-5.
Electrical properties
Surface resistivity
Volume resistivity
Dielectric strength
Dielectric constant
Arc resistance
18
18
18
18
18
2.
2-1.
2-2.
2-3.
2-4.
2-5.
2-6.
2-7.
2-8.
2-9.
2-10.
6. Resistance to fuels and chemicals
6-1. Fuel resistance
6-2. Chemical resistance
19
19
7. Resistance to light and weather
7-1. Light resistance grade
7-2. Weather resistance grade
20
20
8.
8-1.
8-2.
8-3.
8-4.
21
21
25
25
Processing of KEPITAL
Equipment
Injection molding
Safety recommendation
Troubleshooting guide
9. UL approval
27
10. Applications
28
11. Quality, standard accreditation
and environmental management system
34
1. General Information
KEPITAL® is the trade name for the polyacetal copolymer products of Korean Engineering Plastics Co., Ltd.
KEPITAL® has well balanced physical and mechanical
properties with a good combination of highly crystalline
and thermally stable structure. KEPITAL provides not
only excellent mechanical and physical properties but
also resistance to various chemicals and a wide processing window.
The characteristics of KEPITAL® are as follows:
· High mechanical properties
· High fatigue resistance
· Long-term dimensional stability
KEPITAL’s product range, from standard unfilled grades
to specialties, is well-balanced with inherent properties
in order to meet both general purposes and particular
requirements.
KEPITAL® is easily processed to manufacture the
finished product through the typical processes of both
injection molding and extrusion. Therefore, KEPITAL®
has been widely used in products such as automotive,
electronics, consumer goods, etc.
This brochure provides the physical and chemical properties of KEPITAL, processing information and diverse
applications to help chose the right KEPITAL® grade.
· Excellent fuel resistance
· Excellent creep resistance
·S
uperior friction resistance and wear resistance
characteristics
·S
uperior chemical resistance and alkali resistance
1-1. KEPITAL Nomenclature
F xx - OO
1. Grade 2. Flowability 3. Characteristic
1. Grade
(1) Standard unfilled grades: F
(2) Reinforced & filled grades
FG: Glass fiber reinforced
MF: Milled glass fiber filled
FB: Glass bead filled
FT: Whisker filled
TC: Talcum filled
(3) Impact modified grades: TE
(4) Low friction and wear grades
FL: PTFE modified
FS, TS: Silicone modified
FM: MoS2 filled
TX, LO, TP: Special lubricant package formulated
2. Flowability
xx
Melt Flow Rate (g/10 min)
10
15
20
25
30
40
3
6
9
13
28
52
3. Characteristics
OO
03/33
03H
51
52
Characteristic
Mold released / moderate toughness
Higher stiffness and strength than standard
unfilled grade
UV-stabilized, Black color, outdoor
UV-stabilized, Natural color, indoor
korea engineering plastics
3
1-2. Characteristic of KEPITAL
Standard unfilled grades
Grades
Characteristics
Application
Melt Flow Rate
(g/10min)
Name
3.0
F10
High viscosity (low flow) grade with max Injection molding requiring toughness or extrusion-stock
toughness without modification
shapes; rod, plate, tube and pipes
6.0
F15
Intermediate flowability between F10
and F20
Injection molded parts or extruded rod, plate, tube and pipes
9.0
F20
Medium viscosity grade for general
purpose with well balanced properties
in demanding applications
Injection molded parts and extruded shapes with thinner wall
section
13
F25
General purpose with slightly higher
flow property
Injection molded parts requiring better flow and less critical
demand on toughness
28
F30
Low viscosity (high flow) grade
Injection molded parts with geometrically long flow paths, thin
wall or small shapes out of multi-cavities
52
F40
Ultra high flow grade
Very thin walled or small injection molded parts
Reinforced · Filled grades
Grades
Classification
Name
Characteristics
Application
Glass fiber reinforced
FG2025K
FG2015
FG2025
High rigidity
stiffness
Parts where improved mechanical strength such as stiffness, fatigue & creep
resistance, high HDT etc. is required
Milled fiber filled
MF3025
High stiffness
Low deformation
Parts required of high stiffness with dimensional stability such as low warpage
Glass bead filled
FB2030
High stiffness
Low deformation
Appropriate molded parts requiring low deformation under elevated temperature environment
Talcum filled
TC3020
Dimensional
stability
Application requiring excellent dimensional stability
Whisker filled
FT2020
High rigidity
Low strain
Application requiring well balanced stiffness and dimensional stability
Impact modified grades
Grades
Classification
Impact modified
4
Characteristics
Name
TE-21
TE-22
TE-23
Toughened
TE-24
TE-25
Highly impact modified
TE-24S
Super toughened
korea engineering plastics
Application
General mechanical parts where moderately improved toughness
is required or highly stressed parts where super toughness is
needed.
Low friction and wear grades
Grades
Classification
Characteristics
Name
Application
PTFE modified
FL2010
FL2020
Low friction and wear
Injection and extruded parts where low friction coefficient and wear
volume are required such as bushes or conveyor belts etc
Silicone modified
FS2022
Low friction and wear
Parts where reduced friction, wear and noise are needed. FS2022 and
TS-22H are good for parts sliding against plastics
TS-22H
TS-25H
Applications requiring extremely high sliding condition such as high speed,
high load and high PV limits
MoS2 filled
FM2020
FM2520S
Low friction and wear
Bushes and bearings
Special lubricant
package
TP-20
Low friction and wear
against resin
Gears, cams and bearings moving against same resin
LO-21
Low friction and wear
to metal
Gears, cams and bearings against metal
TX-11H
TX-21
TX-31
Low friction and wear & Mechanical parts requiring noise reduction and low coefficient of friction
noise reduction
against either plastics or metal under moderate moving condition
GR-30
Low friction and wear
against metal
Mechanical parts where dimensional stability at elevated temperature as
well as low friction and wear against metal are needed
UV-stabilized grades
Grades
Classification
Natural color
Black color
Characteristics
Name
Application
F20-52
F30-52
UV natural
Parts where exposure to UV, such as automotive interiors
F20-52G
GD-52
Low gloss
Parts requiring low surface gloss in addition to UV screen
F20-51
UV black
Parts exposed to UV for non-critical outdoor
F20-51U
UV black and
improved impact
Appropriate to use outdoors and in UV exposure environments, in particular
for application with parts requiring improved impact
Conductive, anti-static grades
Grades
Classification
Conductive
Anti-static/
static dissipative
Name
Characteristics
Application
ET-20S
ET-20A
Conductive carbon
black powder filled
Varied applications requiring conductive level of electrical property.
ET-20A shows superior performance in fuel contact applications
FA-20
High strength
Parts requiring not only conductivity but also high strength
FV-30A
Anti-static
Parts in demanding applications for static electricity discharge
ED-10
ES-20
Static dissipative
Parts requiring suppression of static electricity generation and prevention of
dust contamination and electrical noise generation
korea engineering plastics
5
1-3. Typical properties of KEPITAL
Standard unfilled grades
Description
General
High viscosity
High rigidity
Medium viscosity
Low
viscosity
Extra
low viscosity
High
viscosity
F10-03H F25-03H
Medium
viscosity
Grade
Test method
Unit
F10-01
F10-02
F15-33
F20-03
F25-03
F30-03
F40-03
ISO 1183
g/cm3
1.41
1.41
1.41
1.41
1.41
1.41
1.41
1.41
1.41
Water
Absorption
ISO 62
%
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
Tensile strength
ISO 527
MPa
63
63
65
65
65
65
65
68
68
Elongation
at yield
ISO 527
%
10
10
10
10
9
8
8
12
10
Nominal strain
at break
ISO 527
%
40
40
35
35
33
25
20
40
32
Flexural strength
ISO 178
MPa
82
83
84
87
90
90
93
90
94
Flexural modulus
ISO 178
MPa
2350
2400
2450
2550
2650
2700
2750
2650
2800
Notched Charpy
impact strength
ISO 179
KJ/m2
7.0
7.0
7.0
6.5
6.0
5.5
5.0
7.0
6.5
Melt flow rate
ISO 1133
g/10 min
3
3
6
9
13
28
52
3
13
Melting point
ISO 3146
°C
165
165
165
165
165
165
165
168
168
ISO 75
°C
96
96
96
100
100
101
101
100
101
Coefficient of
linear thermal
expansion
ISO 11359
x10-5/°C
12
12
12
12
12
12
12
12
12
Surface resistivity
IEC 60093
Ω
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
Volume resistivity
IEC 60093
Ω · cm
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
Dielectric strength
IEC 60243
kV/mm
19
19
19
19
19
19
19
19
19
%
2.2
2.2
2.0
2.0
2.0
2.0
2.0
2.2
2.0
Property
Density
Physical
properties
Mechanical
properties
Thermal
properties
Electrical
properties
Other
Heat Deflection
temperature
(1.8 MPa)
Mold shrinkage
KEP
(t3 mm, ø100 mm) (Flow direction)
* The information contained in this data sheet is based on our current knowledge and experience, so it may change as new knowledge and experience become available. This
information is based on only above-mentioned product produced in Korea Engineering Plastics Co., Ltd.(“KEP”) through relevant test methods and conditions and does not relate
to any products made of this product with the inclusion of other additives, such as processing aids or colorants. This information should not be construed as a promise or guarantee
of specific properties of this product described or its suitability for a particular application, so users make their own determination as to its suitability to their purpose prior to use this
product. It is the sole responsibility of the users to investigate whether any existing patents are infringed by the use of this product. This product is not intended for use in medical and
dental implants and users should meet all safety and health standards. KEP makes no warranty and assumes no liability in connection with any use of this information.
6
korea engineering plastics
Reinforced & filled grade
Low friction and wear grade
Glass reinforced & filled
Glass Fiber
Glass
Bead
FG2025K FG2015 FG2025
FB2030
Silicone modified
Milled
GF
Talcum
filled
Whisker
filled
PTFE modified
General
MF3025 TC3020
MoS2 filled
Special
lubricant
package
FM2020 FM2520S
TP-20
Specialty
FT2020
FL2010
FL2020
FS2022
TS-22H
TS-25H
1.47
1.50
1.59
1.64
1.59
1.56
1.59
1.45
1.51
1.40
1.40
1.40
1.43
1.38
1.38
0.2
0.2
0.2
0.2
0.2
0.2
0.23
0.19
0.18
0.2
0.2
0.2
0.2
0.2
0.2
110
120
160
58
78
67
86
55
45
60
65
60
65
58
57
–
–
–
–
–
–
–
9.5
10
12
10.5
8.5
9.5
10
10.5
3.8
3.6
3.0
4.0
4.9
5.6
2.7
14
14.5
48
20
23
20
33
34
160
175
220
97
129
112
146
80
70
82
88
83
90
80
81
4750
5200
8250
4050
5530
5290
6800
2400
2150
2400
2600
2550
2690
2400
2450
6.5
7.0
8.0
2.5
3.8
3.8
3.6
3.5
3.0
8.5
6.5
5.5
5.5
5.5
5.5
13
11.5
7
19
16
5
15
8
5
10
13
24
11
10.5
10
165
165
165
165
165
165
165
165
165
165
165
168
165
165
165
–
–
162
–
–
–
–
–
–
–
98
98
–
–
–
6
5
3
9
9
7
6
13
13
13
13
13
13
13
13
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
–
–
23
20
–
21
–
16
16
–
–
–
–
–
–
1.0
0.8
0.5
1.5
1.3
1.6
0.9
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
korea engineering plastics
7
Low friction and wear grade
Impact modified grade
Special lubricant package
High toughness
Description
Grade
Test method
Unit
LO-21
TX-11H
TX-21
TX-31
GR-30
TE-21
TE-22
TE-23
TE-24
ISO 1183
g/cm3
1.39
1.40
1.39
1.39
1.43
1.39
1.37
1.36
1.35
Water
Absorption
ISO 62
%
0.2
0.2
0.2
0.2
0.2
0.22
0.23
0.24
0.24
Tensile strength
ISO 527
MPa
60
64
58
56
48
57
51
45
41
Elongation
at yield
ISO 527
%
10
12
10
8
9
9
11
12
13
Nominal strain
at break
ISO 527
%
26
40
33
35
40
40
>50
>50
>60
Flexural strength
ISO 178
MPa
81
86
79
80
66
76
68
60
53
Flexural modulus
ISO 178
MPa
2450
2550
2350
2400
2150
2150
1900
1650
1450
Notched Charpy
impact strength
ISO 179
KJ/m2
5.5
7.5
7.5
7.0
5.5
8.0
11.0
13.0
18.0
Melt flow rate
ISO 1133
g/10 min
9.5
5
16
30
20
11
8.5
8
6
Melting point
ISO 3146
°C
165
168
165
165
165
165
165
165
165
ISO 75
°C
95
97
–
89
–
84
76
76
66
Coefficient of
linear thermal
expansion
ISO 11359
x10-5/°C
13
13
13
13
13
13
13
13
13
Surface resistivity
IEC 60093
Ω
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
Volume resistivity
IEC 60093
Ω · cm
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
Dielectric strength
IEC 60243
kV/mm
–
–
–
18
–
–
–
–
21
%
2.0
2.0
2.0
2.0
1.8
1.9
1.8
1.8
1.7
Property
Density
Physical
properties
Mechanical
properties
Thermal
properties
Electrical
properties
Other
Heat Deflection
temperature
(1.8 MPa)
Mold shrinkage
KEP
(t3 mm, ø100 mm) (Flow direction)
* The information contained in this data sheet is based on our current knowledge and experience, so it may change as new knowledge and experience become available. This
information is based on only above-mentioned product produced in Korea Engineering Plastics Co., Ltd.(“KEP”) through relevant test methods and conditions and does not relate
to any products made of this product with the inclusion of other additives, such as processing aids or colorants. This information should not be construed as a promise or guarantee
of specific properties of this product described or its suitability for a particular application, so users make their own determination as to its suitability to their purpose prior to use this
product. It is the sole responsibility of the users to investigate whether any existing patents are infringed by the use of this product. This product is not intended for use in medical and
dental implants and users should meet all safety and health standards. KEP makes no warranty and assumes no liability in connection with any use of this information.
8
korea engineering plastics
Impact modified
grade
High
toughness
UV-stabilized grade
General
Black
Low gloss
TE-25
TE-24S
F20-52
F30-52
F20-51
F30-51 F20-52G
1.34
1.32
1.41
1.41
1.41
1.41
–
0.25
0.2
0.2
0.2
39
38
63
63
14
23
10
>60
>100
46
Anti-static/static dissipative
grade
Conductive grade
Impact
resistance
High
General
stiffness
General
Specialty
GD-52
F20-51U
ET-20S
ET-20A
FA-20
FV-30A
ED-10
ES-20
1.41
1.41
1.38
1.38
1.39
1.43
1.41
1.32
1.36
0.2
–
0.2
0.2
–
–
–
–
–
–
62
59
58
59
55
40
52
100
63
43
50
9
9
8
11
7
10
4
8
2
8
18
12
35
37
25
35
40
14
40
12
8
2
25
90
50
46
83
83
88
86
78
86
75
67
76
135
88
50
70
1250
1300
2350
2450
2650
2650
2350
2750
2250
2650
2450
7150
2580
1350
2000
21.0
28.0
6.0
6.0
7.0
7.0
6.0
4.0
8.5
4.0
5.5
4.0
5.0
16.0
12.0
6
2
10
28
10
25
10
25
10.5
11.5
1
3
29
<1
5
165
165
165
165
165
165
165
165
165
165
165
165
165
165
165
–
61
92
–
–
–
–
–
89
88
92
160
97
–
–
13
13
13
13
13
13
13
13
13
–
–
–
–
–
–
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x1016
1x103
1x103
1x103
1x1015
1x109
1x1010
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
1x1014
–
–
–
–
–
–
21
–
19
19
19
19
19
19
19
–
–
–
19
–
–
1.6
1.5
2.0
2.0
2.0
2.0
2.0
–
2.0
1.6
1.8
0.9
2,0
korea engineering plastics
9
2. Physical and mechanical properties
The physical and mechanical properties measured by
standard test methods should be the principle guideline
to select material from an engineer’s stand point. It is
also important to review both short-term (strength, modulus, elongation and impact strength etc) and long-term
properties (creep, stress-relaxation and fatigue etc) in
determining which material to use. This is because of the
fact that plastic materials are affected by varied factors
such as temperature, stress and time.
2-2. KEPITAL stress-strain curve
S-S curves of KEPITAL in tensile and maximum stress,
representing tensile strength are shown in Figure 2-2
and in the following table.
(ISO 527, Temp. 23 °C)
Grade
F20-03
FG2025
TE-24
Tensile strength
(MPa)
65
160
41
Testing speed
(mm/min)
50
50
50
2-1. B
ehavior under short-term stress
The short-term properties of plastics under a stress are
determined by means of stress measurements in tensile/
flexural or sudden blow impact strength, depending on
the materials’ characteristics, level of the stress, loading
speed, temperature and chemical environment. However, long term properties show time dependent behavior.
From the tensile test (ISO 527), such data like elastic
Young’s modulus, strength, and elongation at yield and
break point can be obtained. Those properties are determined from the stress and strain curve (S-S curves) that
shows elastic and plastic behavior of a material under
a dynamic load. When the stresses are removed within
the elastic limit, a thermoplastic is capable to recover
its original shape. But on the other hand, if the stress is
greater than the elastic limit, the material is deformed
permanently after reduction of the stress.
Figure 2-2. .Tensile stress-strain curves for KEPITAL
(ISO 527, Temp. 23 °C)
Yield point A
Stress (S)
Break point B
Strain (e)
Figure 2-1. Tensile Stress-Strain curve
In the graph, A is the yield point and its yield stress represents the stress limit for elastic strain. B is the break
point at which fracture occurs. Tensile strength notes
the maximum stress (max) in the stress-strain curve
(S-S curve). Whereas, when fractured before the yield
point, the maximum stress is called the tensile strength
and there is no yield stress such as in some cases of
reinforced and filled grades
10
korea engineering plastics
Figure 2-3. F
lexural stress-strain curves for KEPITAL
(ISO 178, Temp. 23 °C, Testing speed 2.0 mm/min)
2-3. Temperature dependency on
mechanical properties
KEPITAL maintains balanced physical and mechanical
property characteristics over a wide range of temperatures. Figure 2-4 shows stress-strain curves of tensile
tests at various temperatures, and Figure 2-5 shows
dependence of the tensile strength on temperatures.
2-5. Shear strength
Stress (MPa)
The maximum shear stress at which a material can be
maintained prior to shearing (punching) is referred to as
shear strength. Shear strength represents the maximum
load required to completely shear a sample by the maximum strength of a material that is influenced by shear
stress. The shear strength is determined by dividing the
force required to shear the specimen by the area of the
sheared edge. (ASTM D732)
0
2
4
6
8
10
Tensile strength (MPa)
Figure 2-4. Stress-stain curves of F20-03 at various temperatures
(ISO 527, Testing speed 50 mm/min)
Shear strength (MPa)
Strain (%)
Temperature (°C)
Figure 2-6. S
hear strength of KEPITAL F20-03 at various temperatures
(ASTM D732, t 3 mm, testing speed 1.25 mm/min)
2-6. Specific volume
Temperature (°C)
2-4. Impact strength
The impact strength is the energy to withstand a dynamic impact rather than static stress.
There are several ways to evaluate impact strength, and
the Charpy(ISO 179) and Izod (ASTM D256) tests are
mostly used to determine the toughness of plastic materials. Impact strength can be measured in either notched
or un-notched sample; however, it is generally evaluated
after notch-processed on a specimen so that the stress
of an impact load may be concentrated.
KEPITAL has good impact resistance at low temperatures (-30 to -20 °C) as it has a very low glass transition
temperature below -40 °C.
Grade
F20-03
FG2025
TE-24
Impact strength
(kJ/m2)
6.5
8
18
Table 2-1. Notched Charpy impact strength of KEPITAL (ISO 179, 23 °C)
Specific volume (cm3/g)
Figure 2-5. Tensile strength of KEPITAL versus Temperature
(ISO 527, Testing speed 50 mm/min)
Temperature (°C)
Figure 2-7. P-v-T curves of KEPITAL F20-03
As shown in Figure 2-7, the molding shrinkage of
KEPITAL results from both its high crystalline alignment
in solidification and its thermal shrinkage from the molten
state to the solid state as a function of temperature and
pressure. Furthermore, higher cooling rates or cooling
under higher pressures causes less volume shrinkage.
Figure 2-7 notes a steep volume shrinkage of KEPITAL
around 160 °C in the specific volume curves.
korea engineering plastics
11
2-7. Hardness
2-8. Poisson’s ratio
Hardness of a plastic material is usually indicated in
terms of Rockwell Hardness that measures surface
pen-etration with a steel ball under specific conditions.
The Rockwell Hardness scale is dependent on ball
diameter and load (ASTM D785). Rockwell Hardness
of a plastic is divided into a M scale or a R scale,
and the higher number the higher hardness.
Poisson’s ratio () is defined as the ratio of the transverse strain to longitudinal strain of plastic materials
and it is useful to calculate this physical property in
perpendicular direction to loading.
Poisson’s ratio is dependent on time, temperature, stress
etc. The ratio of KEPITAL F20-03 is approximately 0.35.
NH
The following figure shows the hardness differences as a
function of the viscosity of the standard unfilled grades.
Hardness (M Scale)
Y=
H
NH/H
L
NL/L
NL
Figure 2-10. Poisson’s ratio
Figure 2-8. Hardness of standard unfilled grades
Hardness (M Scale)
The following figure shows the hardness differences of
the impact modified grades.
G=
F20-03
TE-22
Figure 2-9. Hardness of impact modified grades
12
The property values of a material used for structure
analysis are tensile modulus (E) and Poisson’s ratio ().
With Poisson’s ratio () and the tensile modulus (E), the
material’s shear modulus (G) can be simply calculated.
It is because a material deforms not only in the tensile
direction but also in its perpendicular direction.
korea engineering plastics
TE-24
E
2(1+ Y )
2-9. Behavior under long-term static stress
F10-03H, 18 MPa
F10-03H, 13 MPa
Strain (%)
When static stresses are loaded to thermoplastics
constantly, not only does the initial strain occur but also
an incremental strain is followed as time goes by due to
its viscoelastic property. Creep is the total strain of initial
elastic deformation and plastic flow for loading time. The
creep behavior of KEPITAL is time, temperature and
load dependent. Therefore a good resilient material like
KEPITAL recovers its original shape entirely or partially
when the loaded stress is removed.
Loading time (h)
The influential factors on KEPITAL
(1) Stress, environmental factors; temperature, high
humidity, chemicals etc.
(2) Molecular weight and filler content
(3) Part design
Strain (%)
The following figures show the tensile creep characteristics and flexural creep characteristics of KEPITAL.
F10-03H, 18 MPa
F10-03H, 13 MPa
Strain (%)
Loading time (h)
Loading time (h)
Figure 2-11. Tensile creep curves of KEPITAL (23 °C, 20 MPa)
Strain (%)
Figure 2-13. Tensile creep behavior of KEPITAL F10-03H
F20-03 20 MPa
F20-03 10 MPa
FG2025 40 MPa
FG2025 20 MPa
Loading time (h)
Strain (%)
Figure 2-14. F
lexural creep curves of KEPITAL FG2025 and F20-03
(23 °C)
Loading time (h)
Figure 2-12. Tensile creep curves of KEPITAL (23 °C, 12 MPa)
The creep failure is a phenomenon in which a part
strained and then eventually fractured under a constant
stress for a long period. Because plastics have viscoelastic properties, creep strain is more readily exhibited
than in metallic materials. In particular, when designing
parts such as pressure resistant containers, screw fasteners, insert formations and insertion parts for a posttreatment process, the creep property of material must
be considered in advance.
korea engineering plastics
13
Figure 2-15 shows the creep rupture of KEPITAL F20-03
with various loads and temperatures.
�
1 < R� < �
0 � �max � �min
Tensile stress (MPa)
80
60
� � � R� � 0
�max � 0 � �min
1
23 °C
40
2
0 � R� �1
�max � �min � 0
3
0
t
60 °C
20
�max = 0
�max � 0
�min = 0
100 °C
10
8
6
1. Range of compression stress
2. Range of alternating stress
4
3. Range of tensile stress
R�: �min/�max
Figure 2-16. Stress range of fatigue test
1
10
102
Time to rupture (h)
103
104
Figure 2-15. Creep rupture curve of KEPITAL F20-03
2-10. Property under cyclic stress
Designing based on a dynamic structure analysis,
obtained where a part is subjected to loading once, can
only provide information if a part can be used without
fracture under the single loading environment.
Engineering parts are often subjected to the fatigue by
stress or strain which is applied repeatedly and periodically over a long period. Fracture or failure that results
from this phenomenon is called fatigue failure. Therefore, when designed, the fatigue properties of a material
should be considered.
Fatigue strength of plastics is generally determined
without failure and it is provided through a S-N curve
(Wöhler curve). The fatigue property is dependant on
the frequency of increasing temperature and various
stresses ranges as shown in Figure 2-16.
R: 0.1
Freq.: 9Hz
0
Figure 2-17 Wöhler curve of KEPITAL FG2025
Figure 2-18 shows the results of fatigue properties of
KEPITAL evaluated based on the strain control method.
In general, there are methods for evaluating the fatigue
characteristic of plastics
(1) Load control method (Load control)
(2) Strain control method (Strain control)
(3) Strain control between grips method
(Position control)
R: 0
Freq.: 1Hz
0
Figure 2-18. F
atigue properties based on the strain control method for
unfilled grades
14
korea engineering plastics
3. Thermal properties
Thermal properties are important elements for establishing the processing conditions of a plastic material and
service temperature of a finish part. It is important to
preview all possible thermal properties; melting point,
heat deflection temperature, coefficient of linear thermal
expansion, thermal conductivity and long-term heat
ageing resistance, prior to design.
3-4. Coefficient of linear thermal expansion
(CLTE)
3-1. M
elting point (Melting temperature, Tm)
The changes in the flow direction for KEPITAL F20-03
and FG2025 are shown in Figure 3-1. The CLTE of F2003 is higher than that of FG2025 since the glass fiber in
FG2025 is aligned to the flow direction while injection
processed, The CLTE in the parallel to flow direction is
lower than that in the perpendicular to flow direction.
KEPITAL has excellent strength and modulus due to its
relatively high crystalinity (65 %) in the final product.
(cf. the crystallinity depends on process conditions)
Type
Tm (°C)
PP
165
POM copolymer
165
POM homopolymer
175
PA6
220
NL/L (µm/mm)
Thermoplastic materials are classified into amorphous
and semi-crystalline polymers.
The later has both a crystalline region and an amorphous region in the final product. The melting point is the
temperature at which the crystalline region melts with
significant volume expansion. At the temperature of a
melting point or higher, the plastic becomes molten and
starts to flow to be processed. The melting point (ISO
3146) is useful information to set up processing temperatures and also determine the temperature at which it
exists in a solid state.
A plastic expands when temperature increases. If a
material is used in a broad range of temperatures or
if both plastic and metal parts are either assembled or
molded together, the CLTE is very important in determining tolerance, interference, dimensional changes and in
forecasting parts failure.
Temperature (°C)
Figure 3-1. Length changes of KEPITAL F20-03 and FG2025
3-2. Specific heat
Specific heat refers to the calories required to raise the
temperature of a unit mass of material by one degree.
For KEPITAL, it increases gradually from an ambient
temperature up to 150 °C, and then drastically increases
at its melting point. At temperatures exceeding the melting point, the specific heat in a molten state is exhibited.
The specific heat of KEPITAL is 0.35 kcal/kg · K in the
solid state at an ambient temperature and 0.63 kcal/kg · K
in the molten phase.
Linear expansion coefficient (X 10-5/°C)
Table 3-1. Melting points of thermoplastics
Temperature (°C)
3-3. Heat deflection temperature
The heat deflection temperature (ISO 75) is the temperature at which specimen exhibits flexural deflection of
0.25 mm under a prescribed load and is used for evalu
ating relative heat resistance for a service temperature.
Figure 3-2. L
inear expansion coefficients of KEPITAL (perpendicular to
flow direction)
korea engineering plastics
15
The linear expansion coefficients of KEPITAL in temperature range are shown in Figure 3-2.
CLTE of F10 to F30 in standard unfilled grades are very
close, so influence of molecular weight is not expected
to be considerable.
Another method for determining the long-term heat resistance of a plastic is RTI (Relative Temperature Index)
of the UL 746B Standard. The value shown on a UL card
indicates the temperature at which at least 50 % of initial
property values are maintained after 100,000 continuous
hours. Table 3-2 lists RTI for the electrical properties,
impact strength and mechanical strength of KEPITAL
F20-03 and FG2025.
3-5. Thermal conductivity
Unlike metals, most thermoplastic materials are insulators with a low thermal conductivity.
The thermal conductivity of KEPITAL standard unfilled
grades is 0.31 W/m · K in its solid state.
Electrical
With impact
strength
Without impact
mechanical strength
F20-03
110 °C
95 °C
100 °C
FG2025
105 °C
90 °C
95 °C
Table 3-2. RTI of KEPITAL F20-03 and FG2025
3-6. Heat ageing
The heat resistance of a plastic may be obtained from
measurement of melting point, heat deflection temperature and linear expansion coefficient. The service temperature of plastics should be determined from long-term
heat ageing experiments. When a plastic is continuously
exposed to evaluated temperature, the mechanical properties gradually deteriorate. Since the degree of property
deterioration depends upon environmental factors such
as temperature, stress, and time, it is necessary to
select a KEPITAL grade upon the designated environmental condition.
Figure 3-3 shows retention rates of tensile strength of
KEPITAL F20-03 compared with its initial tensile strength
in the air for a long period time. The long-term thermal
property of F20-03 is stable up to 100 °C.
Retention rate of tensile strength (%)
150 °C
100 °C
50 °C
Storage time (days)
Figure 3-3. Heat ageing resistance of KEPITAL F20-03
16
Grade
korea engineering plastics
4. Tribological properties
Tribological properties are highly affected by driving
conditions such as pressure on the contacted surface,
velocity, temperature, surface roughness etc. The demand for longer lifetime and cost-effective products has
recently increased; it has brought up the importance and
interest in friction and wear characteristics, especially for
self-lubricated products.
Standard unfilled KEPITAL has widely been used in
sliding parts because of its inherent lubricity. Moreover,
versatile KEPITAL anti-friction & wear grades have been
developed for more finely turned applications requiring
severe wear condition.
4-2. Wear
The wear occurs from mechanism motions such as
abrasion, adhesion and fatigue etc among two or more
sliding materials. Specific wear rate is useful to forecast
KEPITAL’s longevity along with its performance in designated sliding condition.
Description
2.0
TS-25H
Silicone modified
FL2020
PTFE modified
TX-31
Special lubricant package formulated
Table 4-1. Key point to lubricated KEPITAL
4-1. Friction
Friction is the resistance to sliding of two paired surfaces
and is divided by dynamical friction coefficient or static
friction coefficient. In general the friction force causes
a surface temperature increases at high velocity and a
squeak noise under a certain pressure.
Specific wear rate (mm3/N·Km)
Grade
Materials that have the low friction coefficient to particular running conditions are usually effective for good
tribological behavior. TS-25H shows extremely low
friction properties in sliding against itself even under high
pressure in Figure 4-1.
Resin to Metal (S45C)
Speed: 500 mm/s
1.5
1.0
0.5
0
90
110
Load (N)
130
150
Figure 4-2. Specific wear rate of KEPITAL
Significant reduction in wear rate of KEPITAL FL2020 to
standard unfilled grade is shown in Figure 4-2.
Dynamic friction coefficient
Resin to Resin
Speed: 100 mm/s
4-3. PV limits
In terms of frictional behavior, if pressure and speed
gradually increase, at a certain point a material cannot
withstand any further and start to molten. The maximum
value where operation is still possible is called the PV
limit. A material with a high PV limit illustrates that it can
be utilized under more severe operating conditions.
Surface pressure (MPa)
Load (N)
Dynamic friction coefficient
Resin to Metal (S45C)
Speed: 500 mm/s
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
Resin to Resin
0
100
200
300
400
Speed (mm/s)
500
600
Figure 4-3. PV limits of KEPITAL
90
110
130
150
Load (N)
Figure 4-1. Dynamic friction coefficients of KEPITAL
Higher PV limit of TS-25H than standard unfilled grade of
F20-03 and other lubricated grades is shown in Figure 4-3.
korea engineering plastics
17
5. Electrical properties
KEPITAL has good electrical insulating properties and
dielectric strength. Moreover, with recent development in
electrical applications, requirements on static dissipative
or conductive materials are expanding since the combination of mechanical property and electrical property of
KEPITAL is attractive to the electrical markets. KEPITAL
provides the broad range of specialties to satisfy those
needs.
5-1. Surface Resistivity
Surface resistivity (ASTM D257) is insulation resistance
when certain voltage is applied across the surface of
material. In general, it is a most widely used characteristic to identify the electrical behavior of plastics. The
electrical properties of KEPITAL are shown based on the
surface resistivity in Table 5-1.
102~105
106~109/1010~1012
Higher 1014
Conductive
Static dissipative/
Anti-static
Insulator
ET-20A
ED-10
F20-03 etc.
FA-20
ES-20
Table 5-1. Surface resistivity of KEPITAL (unit: Ω)
In particular, KEPITAL ET-20A is designed for fuel delivery systems in passenger cars to have stable electrical
conductivity and significant resistance in contact with
fuels.
KEPITAL FA-20 is reinforced to have high rigidity with
electrical conductivity as to meet requirement for high
mechanical strength and low tendency to creep.
5-2. Volume Resistivity
Volume resistivity refers to the electrical resistance of a
material that is measured when an electric field is applied across the unit cube of a test specimen. Volume resistivity (ASTM D257) is the resistance measured based
on the internal current of a material alone, and it may be
used to determine its applicability as an insulator.
18
korea engineering plastics
5-3. Dielectric Strength
When a voltage is applied to an insulator and incrementally increased, if a certain limit is exceeded, large
current suddenly flows to break down its insulation, and
the limiting value of such voltage is referred to as dielectric strength. Dielectric strength measurement (ASTM
D149) of plastic is determined by dividing the voltage
with a specimen thickness that incurs current when a
test specimen prepared by injection molding is placed
between two electrodes, and a voltage is incrementally
increased from 0.
5-4. Dielectric Constant
If an insulator is inserted in an electric field, electric
charges in the insulator are separated into opposite
electric charge directions of the electric field. Dielectric
constant (ASTM D150) represents the extent of separation between positive charges and negative charges that
are induced at this time.
5-5. Arc Resistance
Arc resistance (ASTM D495) represents the time taken
for insulation characteristics to be broken down by
the current applied to the surface of an insulator. Arc
resistance may sometimes be influenced by moisture,
dust, etc. that is on the surface of the sample.
6. Resistance to fuels and chemicals
A thermoplastic material may show the changes in
mechanical properties and dimensions in environments
in contact with specific chemicals. Temperature and
soaking time have an influence on those properties.
KEPITAL displays the outstanding resistance to fuels
and a variety of neutral organic and inorganic chemicals.
Retention rate (%)
6-1. Fuel resistance
6-2. Chemical resistance
KEPITAL exhibits good resistance to the following
chemicals;
· Organic solvents: Alcohols, Esters, Ketones, Aliphatic
and Aromatic hydrocarbons
· Automotive fluids: Washer fluid, Oils and Coolant etc.
However, strong acids, oxidizing agents and halogens
are strongly recommended to be kept away from
KEPITAL since those break up the chemical structure of
KEPITAL. The changes in physical properties to various
chemicals are illustrated in Table 6-1.
Chemical
Immersion time (h)
Retention rate (%)
Figure 6-1. Changes of KEPITAL F20-03 in tensile strength
Immersion time (h)
Figure 6-2. Changes of KEPITAL F20-03 in weight
Automotive fuels in gasoline and diesel diversify their
compositions upon regions and OEM’s specification. To
promote consistent tests with respect to differences in
composition, testing fuels have been selected and used.
KEPITAL F20-03 has distinctive resistance with respect
to various testing fuels, including gasoline and diesel.
The test results of F20-03 to gasoline and diesel are
shown in Figures 6-1 and 6-2.
KEPITAL has the good stability in terms of mechanical
properties and dimensions in contact with fuels even at
evaluated temperature. Therefore, KEPITAL has been
used in various automotive fuel applications.
Immersion
time (h)
Temperature
(°C)
Measurements
Retention rate (%)
Tensile
Weight Length
strength
Fuel C
360
60
95
102
102
SME20
5,040
90
93
100
100
100,2
Iso-octane
19,680
23
97
100,1
Gasoline
1,000
65
92
101
100
Diesel
1,000
90
100
100
100
Methanol
8,760
50
88
102
101
Ethanol
8,760
50
89
102
101
102
Acetone
8,760
23
83
104
Toluene
8,760
50
90
103
102
Benzene
6,600
60
90
104
102
Carbon tetrachloride
8,760
23
98
102
100
Ethylene glycol
(100%)
480
120
89
–
–
Acetic acid 1%
8,760
23
101
100
100
Sulfuric acid 1%
4,320
23
100
100
100
Hydrochlorid acid 10%
960
40
100
99
100
Sodium hydroxide
10%
552
23
102
100
100
Sodium hypochlorite
(Effective chlorine
3 ppm)
552
23
100
100
–
One-Luber No. 2
2,400
100
105
100
100
Dow Corning FS44MA
2,400
100
106
100
100
Cosmo Limax No. 2
2,880
120
101
99
99
Cutting fluid Yushiro
EE56
552
23
100
100
100
Silicon oil
3,120
130
106
100
99
Food grade salad oil
1,920
80
104
–
–
Copy diazo development solution SD
552
23
96
–
–
1,200
50
101
102
101
960
40
101
100
100
100
Photographic development solution
Photographic fixing
solution
Hot water
1,000
85
103
100
Anti-freeze
5,000
23
103
–
–
Engine oil
5,000
23
105
–
–
Gear oil
5,000
23
103
–
–
Please consider to make practical tests with application under real circumstances
to make sure that part will last for a certain period without failure as the above
result will change by testing conditions, temperature, the concentrate of chemical
and immersing period etc. and unexpected effects.
Table 6-1. C
hemical resistance of KEPITAL after immersion in various
chemicals
korea engineering plastics
19
7. Resistance to light and weather
With exposure to sunlight, plastics become very sensitive to ultraviolet rays. The UV causes discoloration and
surface chalking resulting in decomposition, and finally
serious deterioration of mechanical properties.
KEPITAL UV-stabilized formulations can prolong the
service life of applications with specially formulated
UV-packages. Resistance to light and weather is usually
evaluated through accelerated weathering tests and outdoor exposures for specific times. In general OEM specification recommends the outdoor testing be conducted
by means of weather-o-meter or outdoor exposure in
Florida and Arizona.
Weather
Rate of annual sunny days
Florida
69 %
85 %
280 MJ/m2
334 MJ/m2
Annual sunlight radiation
6588 MJ/m2
8004 MJ/m2
32 °C
40 °C
111
32
Annual raining days
KEPITAL Fxx-52 and Fxx-52G are products with light
resistance and are intended for interior applications.
In addition to natural colors, they are processed with
various colors.
The color changes of F20-52 in beige, gray and red
are less than that of F20-52 in natural color after accelerated weathering according to SAE J2412 in Figure 7-1.
Arizona
Annual UV radiation (385 nm)
Average temperature in summer
7-1. Light resistance grade
Table 7-1. Outdoor exposure test environment
Exposure time (h)
The accelerated weathering equipment can have three
light sources such as carbon arc, xenon lamp, and UV
lamp. Recently, the xenon lamp, with a spectrum similar
to that of sunlight, is generally used. Radiation intensity
and other conditions; filter combinations, temperature,
cycle configuration, are specifically set up according to
the test method.
Figure 7-1. Color changes of F20-52 and F30-52
The SAE (Society of Automotive Engineers) standards
prescribe that different conditions which reflect the
outdoor environment be applied to the accelerated
weathering test depending upon the interior or exterior
application. For interior applications, the cyclic conditions
take day and night into account, while for the exterior
applications, the water shower has been taken to simulate raining. For light resistance and weather resistance
of plastics, changes in colorfastness, surface gloss or
mechanical properties are measured after exposure to
outdoor or accelerated weathering.
The weather resistance of F20-51U in colorfastness was
measured according to accelerated weathering SAE
J2527 in Figure 7-2.
7-2. Weather resistance grade
KEPITAL Fxx-51 and Fxx-51U are products in black
with UV-stabilization and were developed for exterior
applications.
Exposure time (h)
7-2. Color changes of F20-51U
20
korea engineering plastics
8. Processing of KEPITAL
8-1. Equipment
Injection molding is one of the common manufacturing methods for thermoplastics including KEPITAL as
to allow even complicated design and cost-effective
production. Therefore, understanding the processing of
injection molding for KEPITAL is very important.
In order to obtain a high quality of product out of
KEPITAL, the recommendations and check-points on the
injection molding machine are the following :
1) Open nozzle is recommended with individual band
heater on the cylinder as this type has advantage on
gaseous product out of thermal decomposition without
pressure building-up when molding cycle is stopped
and interrupted with leaving melt in cylinder for overresidence time to KEPITAL.
2) Non-return valve should be regularly checked to
achieve holding pressure and cushion not to cause
processed parts of sink mark, big variation of weight
and dimension.
3) Compression zone in screw is recommended of 25
to 30 % in screw length. Improper compression zone
length may not only over-heat material but also lack of
pressure build-up in the plasticizing.
[Recommendations on injection molding machine]
1) The one shot weight for KEPITAL is 20-50 % of
machine capacity
2) L/D: 20-24
3) Compression ratio: 3/1~4/1
4) W
hen processing glass-fiber reinforced KPEITAL,
wear resistant plasticizing unit is advisable and regular checking wear on screw.
8-2. Injection molding
In mold fabrication, it is essential to previously review the
dimensional precision, flow characteristics of the raw material, consistency of product and cost-effectiveness etc.
| 8-2-1. Pre-drying |
Being non-hydroscopic material, KEPITAL in its original
packages can be processed without pre-drying unless
it is exposed to a humid atmosphere for a prolonged
period of time. However, sometimes moisture that exists
on the surface of pellet caused by improper handling or
storage may result in a silver streak or nozzle drooling,
so drying prior to molding may be necessary to prevent
KEPITAL from these problems. In addition, in some
cases, pre-drying is effective in reducing odor, mold
deposit and in achieving a good appearance. Drying
conditions is recommended at 80-90 °C for 3-4 hours.
| 8-2-2. Melt temperature |
The melt temperature of KEPITAL in general is from 180
to 210 °C, preferably 190~200°C.
In common the melt temperature rises above the temperature at metering zone by 10-20°C, this results from
mechanical shear heating during plasticizing.
Non-return valve
Feed zone
Compression
zone
0.5L-0.4L
0.25L-0.3L
Metering
Nozzle
zone
0.25L-0.3L
Figure 8-1. Typical injection molding screw for KEPITAL
korea engineering plastics
21
Grade
Nozzle
Unfilled standard
UV-stabilized
impact modified
FG
MF
FB
180
210 °C
Metering
zone
Compression
zone
Feed
zone
190 °C
180 °C
170 °C
200 °C
190 °C
170 °C
The cylinder temperatures above are based on standard conditions and may vary
with the capacity of the injection machine.
Table 8-1. Typical cylinder temperature for KEPITAL
Cylinder temperature (°C)
When the melt improperly has a long residence time
in the plasticizing unit, over-heating causes it thermal
degradation, which results in discoloration, impairing
mechanical properties etc. The processing window; temperature versus melt residence time in the cylinder for
standard unfilled grade is shown in Figure 8-2.
Over-heated range
Moldable range
Safe molding range
Residence time (minute)
Figure 8-2. Molding temperature versus melt residence time in cylinder
| 8-2-3. Injection pressure |
Injection pressure should be set high enough to achieve
a high injection speed that may not be lowered by a low
injection pressure. Appropriate injection pressure generally ranges 600 to 1200 bar.
| 8-2-5. Injection speed |
The injection speed should be determined by part geometry, gate size and location, surface feature, flow characteristics and mold temperature etc. In general, injection
speed is set at high where there are flow marks, record
marks and sink marks, on the other hand low injection
rate is good to prevent jetting, blush, burn marks or gate
smear, generated by high shear force against cavity wall.
| 8-2-6. Hold pressure |
Hold pressure plays a key role to make KEPITAL parts
optimized in not only dimension but also in mechanical &
physical properties. Because in hold stage (hold/pack),
remaining melt for about 1~5 % of a cavity is forced to
fill into the cavity to compensate for the volume contrac
tion during cooling. The hold (pack) time must be set to
slightly exceed the gate seal time (normally ½ to 1 sec)
at which a gate is completely solidified so that a constant
product may be obtained. As shown in Figure 8-3, the
weight of a molded part increases upon the hold pressure time and then stops at a certain point. At this time
the gate of the part is solidified entirely and no more
material can be incorporated. Finally part weight shows
constant after the gate seal time.
It is recommended that the hold pressure time be maintained until the gate seal is completed. Because the gate
seal time changes mostly upon the shape of cross-section and mold temperature, a proper hold pressure time
must be determined such that the weight and dimension
of a molded product are within a certain range.
By setting optimum hold pressure, molded parts product
with consistent dimensions can be produced. As a rule
of thumb, the hold time can be simply calculated wall
thickness (mm) times 8.
The hold pressure must be set in consideration of dimensional requirements. As a rule, hold pressure amounts to
between 60-90 % of the injection pressure.
26.0
To obtain a good quality product, the mold temperature
must be consistently maintained so that the temperature
distribution in the mold may be achieved uniformly.
25.5
25.0
Weight (g)
| 8-2-4. Mold temperature |
The mold temperature is one of the most important
parameters for injection molding of crystalline polymer in
particular. Mold temperature may widely be set up at 60120 °C, and a general recommendation is 70-90 °C for
general purpose of KEPITAL molding grades. If surface
finish is important or the service temperature of finished
part is expected to be high, higher mold temperature is
recommended.
24.5
24.0
23.5
23.0
0
2
4
6
8
10
Hold pressure time (seconds)
Figure 8-3. Hold pressure time and product weight
22
korea engineering plastics
12
14
Screw diameter
25 mm
40 mm
55 mm
Screw rotational speed (rpm)
120
100
70
Cooling time (seconds)
| 8-2-7. Plasticizing |
Because plasticizing by an excessive fast rotating speed
can make KEPTAL decompose by high shear force, the
reciprocating speed is preferably set as low as possible
unless it does not affect cycle time. Since screw RPM
is dependant on diameter of screw, screw line speed by
screw can be utilized. As a result, screw line speed is
recommended in the range of 150 mm/s to 200 mm/s,
and with respect to the diameter of screws following can
be chosen.
Maximum molded product thickness (mm)
Table 8-2. Screw rotational speed versus screw diameters
Figure 8-4. Cooling time versus mold temperature
| 8-2-8. Cooling |
Total cooling time is determined as sum of “hold pressure time + screw retraction time + a shot safety margin”.
Once KEPITAL is solidified entirely, no additional cooling
time is needed. Most of the time affecting the cooling
time is the hold time. Therefore, supposedly a hold
pressure time is set appropriately, only screw retraction
time needs to be taken into account.
| 8-2-9. Flow characteristics |
Flow path length (mm)
A back pressure of 10-20 bar is generally appropriate.
However, to increase the efficiency of the dispersion of a
color masterbatch (color concentrates) or pigment, higher mixing by increasing back pressure may be required.
In addition high back pressure may be used to eliminate
unmelted particles. In the case of glass fiber reinforced
grades, high back pressure, proportional to rotational
speed leads to breakage of the glass fiber, resulting in
deterioration of mechanical strength. More importantly
excessive back pressure gives rise to lower output along
with longer cycle time. Therefore it should be taken into
consideration in optimizing the back pressure.
Figure 8-5. F
low path length of unfilled standard grades
(melt temperature 200 °C, injection pressure 600 bar, thickness 3 mm spiral flow test)
| Calculation of theoretical cooling time |
S=
S
t

R
Cp
Tx
Tm
Tc
t2
P2A
In
8 (Tc-Tm)
P2 (Tx-Tm)
A=
= Theoretical cooling time
= Maximum part wall-thickness
= Thermal diffusivity of material
= Thermal conductivity
= Specific heat
= Ejection temperature of molding
= Mold temperature
= Cylinder temperature
R
C pR
Flow path length (mm)
In case of a high crystalline resin like KEPITAL, sometimes prolonged cooling time at high mold temperature
may be applied to minimize the residual stress.
Injection pressure (bar)
Figure 8-6. F
low path length of KEPIATL F20-03 as a function of injection
pressures (melt temperature 200 °C, thickness 3 mm spiral
flow test)
korea engineering plastics
23
Shrinkage rate (%)
Figure 8-5 shows the results of the spiral flow test in
which the flow properties of standard unfilled grades
were evaluated. Influence on flowability is found to depend greatly on molecular weight. In addition, Figure 8-6
shows the spiral flow test results of F20-03 at different
injection pressures, indicating that flow characteristics
tend to increase with higher injection pressures.
Archimedes spiral thickness 2 mm
Injection pressure 1,200 bar
Mold temperature 30 °C
Time (h)
Flow path length (mm)
Figure 8-8. S
hrinkage rate changes with mold temperature and
specimen’s thickness
ct
a
mp
S
AB
hi
Hig
In general, when the injection pressure increases, the
shrinkage rate decreases. Dimensions of a product can
be adjusted by changing injection pressure and hold
pressure & time.
S
ce
i
n
sta
s
t re
AB
ryl
No
Figure 8-7. Flow characteristics of KEPITAL and other plastics during
injection molding
| 8-2-10. Cycle time |
The cycle time varies with injection time, hold pressure
time, cooling time, mold open time and safety margin at
each cycle. More importantly cycle time is closely related
to part thickness. From a molder’s stand point, the shorter cycle time is preferable; however, optimizing all time
dependent parameter such as fill rate, hold pressure
time and cooling time is very important to get qualified
parts out of KEPITAL.
Injection pressure (bar)
Figure 8-9. Shrinkage rate changes with injection pressures
(F20-03, Melt temp. 200 °C, Specimen dia. 100 mm, t 2)
Weight
Shrinkage rate (%)
Melt temperature (°C)
Shrinkage rate (%)
a
He
| 8-2-11. Shrinkage |
The shrinkage rate is the most important factor determining a product’s dimensions and is obtained from the
sum of mold shrinkage and post-mold-shrinkage. The
shrinkage value, provided by KEP can be utilized in
designing a part in prototype step. However most of the
shrinkage behavior is affected by not only the plastics’
characteristics but also the processing conditions and
part geometry. Therefore, the shrinkage rate must be
taken into account in consideration of all possible factors.
Figure 8-10. Shrinkage rate changes with holding pressures
(F20-03, Melt temp. 200 °C, Specimen dia. 100 mm, t 2)
When a mold temperature increases, the mold shrinkage
rate increases, and post-mold shrinkage rate decreases.
Figure 8-10 demonstrates that shrinkage rate is high if
hold pressure time is shorter than gate seal time.
24
korea engineering plastics
Parallel to flow
Perpendicular to flow
Holding pressure time (seconds)
8-3. Safety recommendation
| 8-3-1. Safety Precautions during processing |
In processing KEPITAL, an extraction hood should be
equipped over the barrel unit and measures should be
implemented to ensure the ventilation of work place.
KEPITAL decomposes when subjected to excessive
heating over 230 °C or the residence time in cylinder at
200 °C or higher. The decomposition of KEPITAL generates formaldehyde gas that has a pungent smell and
irritates the mucous membrane. Therefore, when thermal
degradation is noticeable, the cylinder should be flushed
by purging out melt and the cylinder temperature must
be reduced at the same time. In order to prevent odor
nuisance, thermally damaged material can be cooled
down in the water bath. In addition, if material stays in
a cylinder under the condition of a blocked nozzle,
formaldehyde gas can rapidly build up a high gaseous
pressure in cylinder. When the pressure is elevated
to a certain extent, the resin and gas in a cylinder are
explosively discharged through the filling hopper, which
could cause serious injury to operators and damage to
an injection molding machine. It is therefore important to
ensure the nozzle is never frozen or obstructed during
processing.
KEPTAL is immiscible with almost all other plastics. If
other materials are introduced and mixed, caution is
required because problems including contamination,
lamination, and deterioration of physical properties arise.
In case of the masterbatch that requires implementation
of colors, a product based on KEPITAL is recommended. In particular, because if even a small amount of
PVC resin is introduced and mixed, it causes serious
degradation to the KEPITAL resin, it is a good practice to
prevent introduction and mixing of materials and also to
use individual injection molding machines for PVC and
KEPITAL only.
| 8-3-1. Changing material in processing |
In general, the cylinder has to be cleaned with a polyolefin before and after KEPTAL processing.
| 8-3-2. The interruption of molding cycle |
Molding cycles can be stopped and interruption by
technical malfunctions in operating machine or other
reasons. In this case, some treatments should be
performed to prevent unnecessary problems. The barrel
temperature should be down to 150 °C but the nozzle
temperature may be maintained to prevent material from
over-heat-ing. If long-period interruption is expected,
stop feeding granule and entirely eject out material from
the cylinder and then lower cylinder and nozzle temperatures.
Whereas increase nozzle temperature to 200 °C and
then go up with cylinder temperature gradually when
restarting machine with KEPITAL to prevent nozzle block
by frozen material.
| 8-3-3. Recycling of KEPITAL |
While recycled material mixing with virgin material does
not particularly interfere with color difference, mechanical
properties, and moldability, the high dosing rate of recycle is likely to cause of contamination, and as increase in
the melt index is accompanied by recycled frequencies.
korea engineering plastics
25
8-4. Troubleshooting guide for KEPITAL
Processing problem
Sticking in cavity
Causes
· Higher resistance to eject force
· Insufficient cooling time
Remedies
· Decrease injection pressure and check for
undercut or insufficient draft
· Clean mold surface
· Increase the number of ejecting pins
· Lower the mold temperature and increase
mold close time
Short shot
Pit mark
Flow mark
· Insufficient flowability by low melt or mold
temperature
· Increase the cylinder temperature and mold
temperature.
· Improper design with small gate or narrow
flow channel
· Increase injection pressure and speed
· Unbalanced filling
· Adjust runner balance
· Insufficient metering stroke
· Increase metering stroke
· Low injection speed
· Increase injection speed
· Low holding pressure
· Increase injection and holding pressure
· Low melt or mold temperature
· Increase melt or mold temperature
· Slow injection speed
· Increase injection speed
· Low mold temperature
· Change the gate location or enlarge gate
size
· Enlarge the gate
· Increase mold temperature
Silver streak
· High moisture in granule
· Drying at 80-90 °C for 3-4 hours
· Decomposition by over-heating
· Insufficient gas vent
· Lower the cylinder temperature or shorten
residence time in cylinder
· Air entrap into cylinder
· Check for gas vent
· Contamination
· Increase back pressure
· Check for contamination with PVC
Discoloration or burn mark
· Over-heating or too long residence time in
cylinder
· Lower the cylinder temperature
· Insufficient gas vent
· Decrease injection speed
· Check for gas vent
· Fast injection speed
Contamination
Flash
· Contamination with other material
· Take precautions on handling
· Black speck
· Clean the cylinder
· Low clamping force
· Increase clamping force
· Too high injection pressure or holding
pressure
· Lower injection pressure or holding pressure
· Too fast Injection speed
· Repair mold
· Lower injection speed
· Mold wear
Sink and void
· Too low holding pressure
· Increase holding pressure and time
· Wear of non-return valve
· Increase mold temperature
· Improper cushion
· Gating at thick wall
· Check for non-return valve
26
korea engineering plastics
9. UL Standards
Each grade of KEPITAL has acquired the plastics materials standard (UL Standard) from
Underwriters Laboratories Inc.
Other
Friction and wear resistance grade
Reinforced filled grade
Standard grade
Accredited UL standards of KEPITAL
File no.: E120354
Relative temperature index (°C)
Minimum
Thickness
(mm)
UL94 Flame
Class
Elecric
Material
Designation
Color
F10-xx+
All
0.75
1.5
3.0
6.0
94HB
F20-xx+
All
0.75
1.5
3.0
6.0
F25-xx+
All
F30-xx+
Mechanical
HWI
HAI
HVTR
D495
CTI
100
–
4
3
3
–
0
0
0
0
5
1
95
100
–
4
3
3
–
0
0
0
0
5
1
110
95
100
–
4
3
3
–
0
0
0
0
5
1
94HB
110
95
100
–
4
3
3
–
0
0
0
0
5
1
0.75
1.5
3.0
6.0
94HB
110
95
100
–
4
3
3
–
0
0
0
0
5
1
All
0.75
1.5
3.0
6.0
94HB
110
95
100
–
4
3
3
–
0
0
0
0
5
1
F20-51U(f1)
Bk
0.95
HB
50
50
50
–
–
–
–
–
F20-52+
All
0.75
94HB
110
95
100
–
–
–
–
–
F20-61+
All
0.75
1.5
3.0
6.0
94HB
110
95
100
–
4
3
3
–
0
0
0
0
5
1
FG20-xx+
All
0.75
1.5
3.0
94HB
105
90
95
3
3
2
0
0
6
1
FG2025+
All
0.75
1.5
3.0
94HB
105
90
95
3
3
2
0
0
6
1
With Impact
Without Impact
110
95
94HB
110
0.75
1.5
3.0
6.0
94HB
All
0.75
1.5
3.0
6.0
F40-xx+
All
FV-30+
FB-20#
All
0.75
94HB
50
50
50
–
–
–
–
–
TC30XX
All
0.75
94HB
50
50
50
–
–
–
–
–
FT-20#
All
0.75
94HB
50
50
50
–
–
–
–
–
FL-20#
All
0.75
94HB
50
50
50
–
–
–
–
–
FA-20#
Bk
0.75
94HB
50
50
50
–
–
–
–
–
FS-20#
All
0.75
94HB
50
50
50
–
–
–
–
–
MF-30XX+
All
0.75
94HB
50
50
50
–
–
–
–
–
FC-20#
Bk
0.75
94HB
50
50
50
–
–
–
–
–
FW-2+
All
0.75
94HB
50
50
50
–
–
–
–
–
FM20XX+
All
0.75
94HB
50
50
50
–
–
–
–
–
LO-2&+
All
0.75
94HB
50
50
50
–
–
–
–
–
LO-3&+
All
0.75
94HB
50
50
50
–
–
–
–
–
All
0.92
3.0
94HB
50
50
50
–
–
–
–
–
All
1.50
3.0
94HB
50
50
50
–
–
–
–
–
TP-2&+
All
0.79
3.17
94HB
50
50
50
–
–
–
–
–
FX-2X+
All
0.79
3.17
94HB
50
50
50
–
–
–
–
–
FM25XX+
Bk
0.94
3.0
94HB
50
50
50
–
–
–
–
–
TX-Y1+
All
1.5
3.0
94HB
50
50
50
–
–
–
–
–
TS-2&+
All
0.9-1.0
94HB
50
50
50
–
–
–
–
–
FU20XX+
All
0.75
94HB
50
50
50
–
–
–
–
–
TE-2Z+
All
1.5
94HB
50
50
50
–
–
–
–
–
ET-20+
Bk
0.75
94HB
50
50
50
–
–
–
–
–
FE-2&+
TM-21+
#: may be replaced by a 2-digit. / &: may be replaced by a digit and indicating oil contents. / fl: suitable for outdoor use with respect to Ultraviolet Light, Water Exposure and Immersion in accordance with UL 746C. / XX: may be replaced by one or two digits. / +: may be replaced by alphabet from A to Z.
HWI: Hot wire ignition / HAI: High ampere arc ignition / HVTR: High voltage arc tracking rate / D495: Arc resistance / CTI: Comparative tracking index.
korea engineering plastics
27
10. Applications
Automotive
1
2
3
4
5
6
| 1. Fuel Pump Module
| 2. Window Regulator
| 3. Door Latch
| 4. Inside Door Handle
| 5. Handle Parts
| 6. Side Mirror Adjustment Device
28
korea engineering plastics
Automotive
7
8
9
10
11
12
| 7. Seat Belt
| 8. Speaker Grille
| 9. Combination Switch
| 10. Bumper Bracket
| 11. Ventilation Parts in HVAC
| 12. Clips (Fastener)
korea engineering plastics
29
Electric/Electronic
13
14
15
16
17
18
| 13. Printer Gears
| 14. Gears for CD/ROM
| 15. VCR Deck Parts
| 16. VCR Parts
| 17. Door Latch for Microwave Oven
| 18. Fan Motor Parts
30
korea engineering plastics
Electric/Electronic
19
20
21
22
23
24
| 19. Washing Machine Part
| 20. Washing Mashine Nipple Parts
| 21. Timer Parts
| 22. Washing Machine Valve Parts
| 23. A/V Tape Parts
| 24. Gears for Camera
korea engineering plastics
31
Construction & Consumer goods
25
26
27
28
29
30
| 25. Gears for Toys
| 26. Sanitary Parts
| 27. Tube Guide of Cylinder for Chair
| 28. Impeller and Fitting for Pump
| 29. Zippers for Clothing and Bags
| 30. Buckles for Bags
32
korea engineering plastics
Construction & Consumer goods
31
32
33
34
35
36
| 31. Semi-finished Products
| 32. Holders, Gears and Balls for Blinds
| 33. Conveyor Belt
| 34. Juice Blender Parts
| 35. Clips for Medical Applications
| 36. Infrared Therapeutic Machine Parts
korea engineering plastics
33
11. Quality and standard accreditation
Korea Engineering Plastics Co., Ltd. is committed to creating profitable future for customers and has met the re
quirements of international quality accreditation systems
such as ISO/TS16949 and ISO 14001, starting with ISO
9000. This global company continues to rise to meet its
challenges and is also recognized as an official standard
testing agency based on ISO 17025 by KOLAS (Korea
Laboratory Accreditation Scheme) in an effort to improve
its reliability in test results. Furthermore, we have
obtained standard accreditations from UL, CSA, NSF
and BS6920, compliance to FDA, and have established
global excellence in terms of quality and stability.
Classification
Accreditation standard
System standard
· ISO/TS 16949
· ISO 9001
· ISO 14001
· K-OHSMS 18001
· ISO 17025 (KOLAS)
ISO/TS 16949:Integrated quality management system in automotive
ISO 9001:
Quality management system
ISO 14001:
Environment management system
K-OHSMS 18001:
Safety and health management system
ISO 17025 (KQLAS): Test agency accreditation system
Standard accreditation certificate
ISO/TS 16949
34
korea engineering plastics
ISO 9001
ISO 14001
ISO 17025 (KOLAS)
Properties are subject to change upon new knowledge and development
Although the information and recommendations set forth
herein are presented in good faith and believed to be correct, we recommend that persons receiving information
must make their own determination as to its suitability to
their purposes prior to use. The information is based on
natural colored products only through relevant test methods and conditions. It is the obligation of the customer to
determine whether a particular material and part design
is suitable for a particular application. The customer is
responsible for evaluating the performance of all parts
containing plastics prior to their commercialization.
KOREA ENGINEERING PLASTICS CO., LTD. assumes
no warranty or liability of, express or implied, as to the
accuracy or completeness thereof, or any other nature
regarding designs, products, or information may be
used without infringing the intellectual property rights of
others. Further, the data furnished by KEP are not intent
to replace any testing required to determine a suitability
of any application and set a specification limit for design.
korea engineering plastics
35
KEP Headquarters
KEP Americas, LLC
KEP Europe GmbH
KEP China
450, Kongduk-Dong, Mapo-Ku
106 North Denton Tap Road Suite 210-202
Rheingaustraße 190-196
A1905, HongQiao Shanghai Plaza, 100
Seoul
Coppell, TX 75019
D-65203 Wiesbaden
Zunyi Road, Shanghai
Korea, 121-020
USA
Germany
China
Phone: +82 2 707-6840-8
Phone: +1 888 KEPITAL
Phone: +49 (0)611 962-7381
Phone: +86 21 6237-1972
Telefax:+82 2 714-9235
Telefax:+1 888 537-3291
Telefax:+49 (0)611 962-9132
Telefax:+86 21 6237-1803
E-Mail: [email protected]
E-Mail: [email protected]
E-Mail: [email protected]
E-Mail: [email protected]
BR02_EN_03_09