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CoF and wear reduction in plastics for
tribological applications in PA and POM
PolyTrib 2016 Ljubljana, Slovenia
Clement Descamps & Michal Hrebičík
Agenda
– About Dow Corning
– Improving wear resistance and CoF• In unfilled PA 6
• In glass fiber filled PA6
• In POM
– Conclusion
Dow Corning Corporation is a Global Leader in Silicon-based Technology and Innovation
7,000 products and services
25,000 customers
11,000 employees
$5.7 billion USD in sales in 2013
Focused on sustainability and Responsible Care®
Dow Corning was formed in 1943 to explore the application of the Si atom
Dow Corning is a wholly owned subsidiary of The Dow Chemical Company
Headquartered in Midland, Michigan
Dow Corning and Multibase
Multibase is a
100% Subsidiary
of Dow Corning
SINCE 2002
We simplify access to
the uniqueness of silicone
technology, from fluids
to pellets.
Unfilled PA6
Wear & COF improvement in PA6
3 possible solutions
– Pellets: Dow Corning® HMB-1103 Masterbatch
– Pellets: Dow Corning® 50-011 Masterbatch
– Powder: Dow Corning® 31-441
Features and benefits
– Improved processability
– Improved Slip and Wear
– Maintained mechanical properties and density
Experimental
– PA was predried (3 hrs/80°C)
– Dow Corning® 31-441, Dow Corning® HMB-1103 and
Dow Corning® MB 50-011 were mixed into a dry-PA
and compounded in a TSE 20/40
– Before injection the compound was dried (3 hrs/80°C)
– Injection run on Engel 80 tons press
– Before testing the dumbbels were kept min 1 week
conditioned at 20°C
Test method
Wear measurement by SRV equipment
Counter material 100Cr6
Stoke 2x2.5 mm
Load 25 and 50 N
Frequency 5 Hz
Temperature 25°C
Humidity 40-60%
Duration 1000 s
COF results
COF from the wear test 25 N and a 10 mm ball
0.550
0.1700.150
0.280
0.150
0.235
0.140
0.230
0.100
0.000
0.100
0.200
0.300
0.400
0.500
0.600
Neat PA6 8 % PTFE 15 % PTFE 1% 31-441 2 % 31-4412 % MB50-011
4 % MB50-011
1.65 %HMB-1103
3.3 %HMB-1103
CO
F
Formulations
Average COF - 25 N - 10 mm ball
Wear results
57.50
0.00 0.00
46.25
8.50
31.25
0.00
17.00
0.000.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
Neat PA6 8 % PTFE 15 % PTFE 1% 31-441 2 % 31-441 2 % MB50-011 4 % MB50-011 1.65 % HMB-1103
3.3 % HMB-1103
Avera
ge d
epth
(um
)
Formulations
Average depth of damaged area (25 N - 10 mm ball)measured by perthometer
Wear from the wear test 25 N and a 10 mm ball
Impact results
5.2
3.93.6
7.0577.3
7.03
6.3
5.232
4.8
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
Neat PA6 8 % PTFE 15 % PTFE 1% 31-441 2 % 31-441 2 % MB50-011
4 % MB50-011
1.65 % HMB-1103
3.3 % HMB-1103
RN
I(K
j/m
²)
Formulations
Impact (charpy notched)
Processing
* Performed in a non reinforced PA61 15wt% PTFE benchmark 2 All formulations using 2wt% Si-active (3.3wt% HMB-1103).
3.3wt% Dow Corning® HMB-1103 shows similar torque reduction vs 15wt%
PTFE benchmark while maintaining initial PA injectability.
Torque Relative Spiral Flow
(%)
No additive 31 100
PTFE1 27 83
HMB-11032 27 100
Conclusions
Processing Injectability Mechanics Density Slip Wear
PTFE +++ - 0 - +++ +++
31-441 +++ 0 + 0 +++ ++
HMB-1103 +++ 0 0 0 +++ +++
50-011 +++ +++ + 0 +++ +++
Si additives provide same or better CoF and wear performances
Mechanical properties are not deteriorated as compared to PTFE
- Significant improvement of Notched Impact resistance
- Decreased density of the final compound vs PTFE
- No exudation of silicone
- No blooming because of UHMW silicone (compared to LMW silicone oil)
Glass fibers
reinforced PA6
The issue to be solved in GF PA
Reinforcement of polyamide formulation with glass fibers
always comes at the cost of:
• Processability
• Tribological behaviors
• Density
Processing aids can increase productivity while
optimizing tribological properties
PTFE are commonly used, but they come of the cost of:
- Density
- mechanical properties
- Environmental constraints
Wear and CoF improvment in GF/PA
- Improved processability
- Improved Slip and Wear
- Maintained mechanical properties and density
HMB-1103 DC31-441
Active content 100% 100%
Physical form Pellets Powder
Process Pellets mix Powder mix
Melt temperature 101 C° 60 - 70 C°
Recommended usage level 3 wt% 2 wt%
Compound nature Neat and GF PA GF PA
Experimental
30wt% glass fibers reinforced PA6 compared with 15wt% PTFE
Drying: 80°C/3H
Twin screws extruder L/D = 40, D= 20
Drying: 110°C/1H
Injection of ISO 527
• Injection molding: 80T Engel
Before testing the dumbbels were kept min 1 week conditioned at
20C
Test method
Wear measurement by SRV equipment
Counter material 100Cr6
Stoke 2x2.5 mm
Load 25 and 50 N
Frequency 5 Hz
Temperature 25°C
Humidity 40-60%
Duration 1000 s
COF results
COF from the wear test 25 N and a 10 mm ball
0.550
0.073 0.080
0.420
0.130
0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.700
Neat PA6 8 % PTFE 15 % PTFE 1.65 % HMB-1103 3.3 % HMB-1103
CO
F
Formulations
Average COF - 25 N - 10 mm ball
Wear results
Wear from the wear test 25 N and a 10 mm ball
17.5
0 0
52.5
00
20
40
60
80
100
120
Neat PA6 8 % PTFE 15 % PTFE 1.65 % HMB-1103 3.3 % HMB-1103
Avera
ge d
epth
(um
)
Formulations
Average depth of damaged area (25 N - 10 mm ball)measured by perthometer
Mechanical Properties (ISO 527, ISO 178)
Dow Corning® 31-441 and Dow Corning® HMB-1103 maintain mechanical
properties
Young Modulus
(MPa)
Tensile strength
(Mpa)
Impact charpy
unotched
(kJ/m2)
No additive 8790 161 115
PTFE 9280 142 99
31-441 8670 157 97
HMB-1103 8940 155 115
Processing
Dow Corning® 31-441 increases by minimum 25% throughput & injectability
while reducing torque by 10%.
Torque Melt temperature
(°C)
Relative
Throughputs*
(%)
Relative
Spiral Flow
(%)
No additive 36 340 100 100
PTFE 36 338 116 100
DC 31-441 31 316 127 125
HMB-1103 33 324 113 125
*relative comparisons to maintain a constant machine load
Dow Corning® HMB-1103 demonstrates comparable injectability improvment.
Conclusions
Dow Corning® HMB-1103 provides the same or slightly worse performance in
regards to CoF and wear
- Mechanical properties are not deteriorated as compared to PTFE
- Significant improvement of Unotched Impact resistance
- Decreased density of the final compound vs. PTFE
Processing Injectability Mechanics Density Slip Wear
PTFE 0 0 - - +++ +++
31-441 +++ +++ 0 0 NA NA
HMB-1103 + +++ + 0 +++ +++
50-011 +++ +++ 0 0 NA NA
Conclusions
- Dow Corning® HMB-1103 our best in class Tribological modifiers for
non-reinforced and reinforced PA
- Dow Corning® 31-441 our best in class processing aid
- Improved processability• Up to 25% throuput increase
• Up to 10% torque and Temperature reduction
- Improved Slip and Wear• 3% of DC additives achieve same level of benefit as 15% PTFE
- Maintained mechanical properties and density of GF PA
Polyoxymethylene
Unique Selling Proposition
• Improved COF for POM compounds while maintaining mechanical
performance
• Achieves better COF performance than competing PTFE with
significant lower dosages or Si-Oil with substantial better short and
long-term performance
• Improvement of abrasion resistance
• Improvement of mar resistance for visible areas (e.g. for household
appliances)
• No exudation of Silicone / no blooming because of UHMW Silicone
rather than LMW Silicone oil
• Improved processing (e.g. by torque reduction while extruding/injecting)
• Easy handling: pellet (MB40-606, HMB-1103)
powder (EP5500) form
Product overview
Product overview MB40-006 HMB-1103 EP-5500
Physical form Pellets Pellets Powder
Specific Density 1.23 0.98 0.98
Process Dry Blend Dry Blend Dry Blend
Typical recommended use level 2.5-5wt% 1.5-3.5wt% 1-2wt%
Available packaging 5-25kg’s 5-25kg’s 10-20kg’s
Experimental
− POM dried 3 hours at 100°C
• 3 different types were evaluated – homopolymer, copolymer with 2 different
MVR’s
− HMB-1103 was mixed into a dry-blend and compounded at TSE
20/40
− Before injection the compound was dried (3 hours at 100°C)
− Injection run on Engel 80 tons press
− Before testing the dumbbels were kept min 1 week conditioned at
20C
Test method
Low speed High speed
Testing ball design 12,5mm diameter
Counter Materials Rockwell C hardness 62 or POM
Humidity (%) 55
Force (N) 30 5
Speed (mm/s) 8 200
Test time (min) 45 10 (60*)
T 23 23
Length L (mm) 60 100
# cycles 559 670 (4000*)
Low speed – stick-slip and COF measurement
Equipment: Tribo prufstand 1.6
High speed - COF measurement
Equipment: ball plate polynew
Slow sliding speed COEF: POM ball
High sliding speed COEF: POM ball
Long lasting dynamic COF*
Against POM
Dow Corning’s additives help maintaining long lasting performances while
keeping surface integrity
Surface damages (profilometry*)
POM ball Low Speed High Speed High speed long term
No additive
PTFE
Dow Corning’s
additives
(high loadings)
*surface profilometry measured by mean of perthometer S3P
All Dow Corning brand additives did demonstrate an improvement
of the MAR vs. PTFE
Dow Corning additives for POM
Performance vs neat POM PTFE Dow Corning
MB40-006
Masterbatch
Dow Corning
HMB-1103
Masterbatch
Dow Corning
EP-5500
Powder
Tensile Fmax - +++ +++ +++
Tensile Modulus - +++ +++ +++
Impact - +++ ++ ++
Torque reduction 0 0 0 0
Die pressure 0 ++ + +
POM COF 0 ++ +++ +++
POM long term COF 0 ++ ++ +++
Noise +++ +++ +++ +++
Surface integrity 0 +++ +++ +++
+++ (Excellent) ++ (Good) 0 (Neutral) - (Negative)
Conclusion
- Additive solution for all PA, GF/PA and POM
- Additive level has minimized effect on mechanical
properties, some are even improved (e.g. impact
resistance – anything else)
- Tailored solution for wear and Cof reduction
- Performance comparable and competitive to
PTFE based solutions - brings density and
potential cost in use advantage
The information contained in this communication does not constitute an offer, does not give rise to binding obligations, and
is subject to change without notice to you. The creation of binding obligations will occur only if an agreement is signed by
authorized representatives of Dow Corning and your company. Any reference to competitor materials contained in this
communication is not an endorsement of those materials by Dow Corning or an endorsement by the competitor of Dow
Corning materials.
To the fullest extent permitted by applicable law, Dow Corning disclaims any and all liability with respect to your use or
reliance upon the information. DOW CORNING DOES NOT MAKE ANY WARRANTY OR REPRESENTATION, EXPRESS
OR IMPLIED, WITH RESPECT TO THE UTILITY OR COMPLETENESS OF THE INFORMATION AND DISCLAIMS THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. DOW CORNING
DISCLAIMS LIABILITY FOR ANY INCIDENTAL OR CONSEQUENTIAL DAMAGES.