..
9
Challenges in
Manufacturing of
.: Rio-Based Greases
Dr. Anoop Kumar and Bill Mallory
Royal Mfg Co. LP~ 516s, 25th WAve., Tulsa, 74127, Oklahoma, USA
Abstract:
The buzzwords like “Biodegradable”, “Bio-based”, “Eco
friendly”, and “Green” etc., appear to be complimentary
to each other in lubricant industry and are often
referred to the lubricants/greases prepared in either
vegetable oils or ester fluids. The awareness to use such
vegetable oil based lubricants dates back to 1400 BC
where Egyptian used animal fat or olive oil mixed with
lime, a kind of crude lubricating grease to lubricate
their Chariots. By the end of 19th century, majority of
lubricants and greases were replaced by mineral oil based
products. Since then great advances in manufacturing
technology of these lubricating greases have taken place.
A wide variety of processes for manufacturing of these
lubricating greases have been developed and adopted
by the industry. When it comes the manufacturing of
vegetable oil based greases, these processes becomes
rather complex. One of the reasons for this complexity is
the chemically different nature of mineral and vegetable
oils. What makes manufacturing of vegetable oil based
greases even more complex is the fact that under
certain conditions of reaction, these vegetable oils itself
potentially tends to become chemically reactive to the
some ingredients or possibly tends to polymerize.
The bio-based greases, generally being marketed
industry wide are based on lithium, lithium complex,
clay base, aluminum complex prepared in different types
of vegetable oils depending upon the availability of these
oils locally. While manufacturing these types of greases,
we faced some real challenges in scaling up the processes,
meeting process parameters versus intended quality. This
paper covers some of the aspects of these manufacturing
challenges faced while making lithium, lithium
complex, and aluminum complex greases under varying
processing conditions. The Physico-chemical properties
of thus produced greases have also been covered in this
paper.
Key Words: Lubricating grease, canola oil, vegetable
oil, lithium, lithium complex, aluminum complex,
sulfonate etc.
1.0 Introduction:
The first ever lubricants used by mankind to reduce
friction and wear were perhaps the one derived from
vegetable oils and/or animal sources. It has been reported
that scrapings from the hub of Egyptian chariot showed
the presence of quartz, iron, fat and lime indicating the
use of a kind of lime based grease [1-3]. The use of these
natural resources based lubricants continued to be used
until 19th century, where the discovery of crude oil and
advancement in their refining processes revolutionized
the entire lubricant industry. This gradually replaced
almost all vegetable oils/animal fat based lubricants
and greases by mineral oil based products. The main
reason for their dominance was probably the better
performance, adequate availability and cheaper cost.
Even NLGI 2011 worldwide grease market survey
indicates about 2.4 billion lbs of total worldwide grease
volume, where mineral oil based greases have dominated
by about 92% followed by synthetic and semi-synthetic
– 24 VOLUME 78, NUMBER 5
NLGI
oil based greases totaling about 7%. Bio-based greases
found their entry for the first time in 2010 survey, has
now about meager 1% market share [4].
Since then the technologies have progressed
remarkably, especially in last 200 years. However, the
developments in field of lubricating greases have been
much slower and less scientific. The process of making
lubricating greases in those days probably would have
been much closer to the washing soap making techniques
[5] like the one by boiling wood ash lye with fat Miller
[6] stated that until close to 1800, the universal lubricants
were beef / mutton tallow or a vegetable oil. Hamill [7]
in 1863 formed grease by simply adding pulverized soap
stone to coal/petroleum oil. Lawrence commented that
even the 1930’s method of making lubricating greases
closely resembles to cookery-book stuff [8]. However,
post WWII era has witnessed remarkable progress in the
field of lubricating grease developments. Products based
on different kind of thickeners using wide variety of base
oils and additives system came in to the market. The
manufacturing of lubricating greases, unlike lubricating
oils, has now been regarded as complex and highly
sensitive to processing equipment and parameters. On
the other hand, in late 20th century due to environmental
concerns, drive for green products and renewability
factors once again revived the need of vegetable oil
based lubricants and greases. The support from various
government agencies across the globe, primarily in
Europe, legislative compliance, incentives offered both by
government and non-government agencies have further
spurt the demand of biodegradable / vegetable oil based
lubricants and greases.
is more important from manufacturing stand point is
how to produce these greases in conventional plants
where mineral and synthetic oil based greases are being
produced using those conventional processes. The real
challenge lies in the fact that the chemical composition
and thermal stability of mineral and bio-fluids is
considerably different, it’s very difficult to manufacture
a consistent quality product adopting processes that are
being used conventionally for making mineral/bio-based
greases. For instance, mineral oil based lithium greases
are normally produced by heating up to 400 OF (204
OC) whereas many of the bio-fluids start degradating /
polymerizing at such high temperatures.
1.1 Compositions of mineral and bio-based oils:
Mineral oils primarily consist of mixture of variety
of hydrocarbons which include straight chain,
branched chain, olefins, cyclic compounds, aromatics,
naphthalenes etc [1-3]. These bases oils could be
aromatic, paraffinic, naphthenic, group I, group II,
group III and even synthetic hydrocarbon oils like poly
alpha olefins (PAO) etc. Both naphthenic and paraffinic
type base oils are being used to make lubricating
greases, though the saponification takes place better
in naphthenic oils. These oils are almost non-polar
and non-reactive to the ingredients used for making
lubricating greases.
CH3 (CH2)7CH=CH (CH~C (0) O~CH2
CH3 (CH2)7CH=CH (CH~C(O)O~CH
CH3 (CH2)~C (0) O—CH2
The challenges in front of bio-based lubricating grease
manufacturers are mainly two fold. One meeting the
performance requirements in terms of oxidation stability,
extreme-pressure, water resistance, high temperature
thermal degradation etc. vis-à-vis its mineral oil
counterpart. As the majority of the market is flooded
with mineral oil based products, it’s likely that these
bio-based greases are going to replace mineral oil based
greases. Therefore, user’s expectations from the bio-based
greases demands comparable or better performance
than mineral oil based products. The other one which
Figure-i: Triglyceride of long chain fatty acid
Vegetable oils on the other hand are triglyceride of
long chain fatty acids (Figure-i). These vegetable oils
contain unsaturated double bonds, ester linkage and
vary in composition depending upon type of oil. These
oils as we see do carry reactive sites and under the
influence of temperature and certain functional group,
tend to become reactive. Honary [9] indicated the certain
– 25 NLGI SPOKESMAN, NOVEMBER/DECEMBER 2014
NLGI
vegetable oils tend to oxidize and polymerize at temperature exceeding 150 OC (302 OF) and this
behavior becomes irreversible. The soap formed in such cases looks like a polymeric material with
little lubrication value. Similarly, polymerization of vegetable oils under different conditions has
widely been reported [10-121. As both acids and bases like lithium hydroxides are used to make
greases, there is a possibility of reaction of greases making ingredients with the carrier oil like
vegetable oil and possibly a uncontrolled reaction. This in turn may disturb the stoichiometric
ratios of various ingredients. Therefore, there is a possibility that vegetable oils may not behave the
same fashion as mineral oils perform.
1.2 Conventional Manufacturing Processes:
Unlike lubricating oils, manufacturing of lubricating greases is considered complex and highly
sensitive to manufacturing process parameters. The NLGI Grease Production Survey indicate that
over 90% of worldwide greases produced are based on soap or their complex soap base greases
and are conceptually prepared by the saponification process; alkali hydrolysis of fat / fatty acids.
For making lubricating grease long chain fatty acids/esters (preferably C18) are hydrolyzed by
hydroxides of lithium, calcium, or sodium etc.
(~) From Trig~ycerkies
RCO2CH2
CH2OH
RCO2CH
±
3 MOH
3 RCO2M
-*
+
RCO2CH2
~HOH
CH2OH
(Triglycerides)
Alkali
Metallic salts
(Glycerol)
(N) From Esters:
RCO2R’
(Esters)
±
MOH
Alkali
-~
RCO2M
±
Metallic salts
R’OH
(Alcohol)
(Ni) NeulraN~ation of Fatty Ac~d
RCOOH
(Acid)
±
MOH
Alkali
-~
RCO2M
Metallic salts
+
HOH
(Water)
Lubricating greases in general can both be prepared by continuous manufacturing process
and batch process. The majority of lubricating greases are prepared by batch process as it has
more flexibility in making a variety of products in the same plant. Batch process could both be
open kettle or closed kettle. Both open and closed kettle processes are practiced in the industry
depending upon the type of greases being processed. Most of the lithium and lithium complex
greases are processed in closed kettles under pressure due to better saponification, less process
time and better quality. This is attributed due to the fact that most of the saponification reactions
– 26 VOLUME 78, NUMBER 5
are carried out between a weak acid which normally a long chain fatty acid and weak base like lithium
hydroxide and therefore accelerated condition,s like reaction under pressure, promotes the reaction
faster in forward direction. However, the cost of pressurized reactors is much more than an open kettle
and therefore, many small manufacturers still use open kettle process as for making even lithium
greases. Other greases like calcium sulfonate, aluminum complex, calcium, sodium, polyurea, clay
etc. are generally made in open kettles. The invention of the contactor process by Stratco has indeed
revolutionized the manufacturing of lubricating greases. The most widely produced lithium greases
are preferred to me made through the contactor process [1, 2, 13]. The unique feature of the contactor
process is its high turbulent circulation in a closed cycle path. It is claimed that lithium greases made by
this process provide about 20-30% better yield compared to open kettle process, in addition to the better
quality and efficiency. More recently Honary et.al, reported a microwave process of making lubricating
greases which is claimed to be more efficient and convenient [9]. The various processes of making
different greases are depicted schematically as figure-2.
Lubricating Greases:
Manufacturing Processes
I
4r
Gonlinuous Process
Batch Process
i
OpenKettle
Close Kettle
I
Pressure Kettle
Stratco Contractor
Figure-2
In this paper some interesting results and challenges faced during manufacturing of bio-based greases
using conventional processes and plant has been covered. The lubricating greases covered in this paper
are based on lithium, lithium complex, and aluminum complex.
– 27 NLGI SPOKESMAN, NOVEMBER/DECEMBER 2014
NLGI
2.0 Experimental:
The term bio-based greases refer here to the greases prepared in 100% vegetable oil. The
vegetable oil used in these studies is technical grade canola oil (AP 60), a type of rape seed oil,
supplied by Cargill. Mineral base oils used for making these greases are a blend of paraffinic and
naphthenic oils. The thickeners selected for making bio-based and mineral oil based greases were
of three types, namely lithium 1 2—hydroxy stearate, lithium complex, and aluminum complex. The
greases prepared by open kettle process were both prepared in lab as well as commercial plant. The
grease prepared in commercial plant were of 6000-8000 lbs batch size using thermic fluid heated
kettle with counter rotating paddles hooked with scrappers. The lubricating greases prepared by
closed process were prepared in commercial plant in Stratco contactor at batch size of 7000 lbs.
The greases prepared by contactor processes were first cooked in contactor and then transferred
to open kettle for dehydration, cooling and finishing. The greases were either milled through
Charlotte grease mill or homogenized through APV Gaulin homogenizer. The lab samples were
prepared using Hobart mixture and milled through lab mill. All the greases were tested as per
standard ASTM test methods.
3.0 Manufacturing ofBio-Based Lithium Greases:
As per the NLGI Grease Production Survey [4] about 75% of total worldwide greases are based
on lithium and are the most widely used greases worldwide. These greases are prepared normally
with reaction of 12-hydroxystearic acid (12 HSA) with lithium hydroxide. Alternatively, other
fatty acids or esters being used for making this class of greases are hydrogenated castor oil (HCO),
stearic acid and tallow etc., however most preferred one is 12 HSA. As we use 12 HSA as main
fatty acid to make these greases, our studies are limited to grease prepared with 12 HSA. The a
saponification reaction taking place is shown as under. This reaction can be carried out both in
open kettle process or closed (stratco contactor) process.
aI3(cH2~5duon(cH2)1~co2H
±
J~OHafl,O
-~
GE3(CIT2)sCHOHcCH2)io~O1Li
3.1 Open Kettle Process:
Lithium 12-hydroxy stearate greases in open kettle are normally made by following commonly
adopted method
1. Charging the ingredients:
a. Mineral /synthetic base oil (10-30%) is charged in the kettle
b. Charge fatty acid (12 HSA), lithium hydroxide and water
2. Cooking and Dehydration:
a. Heat slowly by continuously stirring to about 400°F (204°C). Care need to be
taken to minimize foaming.
3. Cooling and finishing:
a. Mass is cooled down to < 190°F (90°C) either by circulating cold oil in kettle
jacket and br by adding finish remainder of oil
b. Additives are added and mixed
– 28 VOLUME 78, NUMBER 5
+
21120
NLGI
4. Homogenization / Milling: Grease is homogenized I milled to get uniform structure and
tested
Typical lithium 12-hydroxy stearate extreme pressure (EP) grease prepared by above process
exhibited the properties as indicated the table -1. Table -1 indicate that the that the grease prepared
by open kettle process uses about 12% soap, exhibited good extreme pressure, rust prevention and
good mechanical stability. In order to check the consistency of grease on storage, the grease was also
tested for worked penetration periodically as indicated by table-i. The test result for over the period
of 1 year indicates that there is practically no change in penetration over the test period of 1 year.
A batch of canola oil based lithium 12-hydroxy stearate grease was prepared in open kettle
adopting the similar process as mentioned above by heating up to 400°F. The finished grease was
milled and tested for intended properties. Test results are tabulated in table-i under lithium 12
hydroxy stearate grease by conventional process. It was interesting to note that when grease was
made using 12% soap as was done in case on mineral oil base grease, it failed to make proper
grease and consistency was too thin. Therefore the grease was prepared using a higher percent
of thickener (18%). The resultant grease was NLGJ 1 consistency and appeared to be stringy
as if some polymerization has taken place. The progress of reaction was also studied by FT-JR
recorded at different times. Figure 3 indicate a comparative FT-JR spectrum of canola oil, lithium
12 hydroxy grease prepared in mineral oil and a canola oil based grease spectrum recorded after
8 hrs of reaction. Both greases clearly indicate 1578 cm-i and 1560 cm-i band corresponding to
the formation of lithium 12-hydroxy stearate, however no significant difference in two greases was
noticed.
WI CWr~dW 00
W~IMirII.WIC,IL~ 1W
I
IQIJ
r,E,
4U
U
4LI_~U
vV~4vonh,rnbnr.s C~rrn 1)
Figure-3
Table indicates that the mechanical stability of the grease made by this process using canola oil
resulted into comparatively inferior product. The storage stability of the grease ran over a period
of 1 year indicate that grease has tendency to harden over a period of time, though the tendency of
hardening reduces with time.
– 29 NLGI SPOKESMAN, NOVEMBER/DECEMBER 2014
NLGI
This difference in resultant grease made in canola oil
using conventional process may be attributed due to
the different nature of the vegetable oil. Mineral oils are
the mixture of hydrocarbons and considered non-polar
and non-reactive to the fatty acid or lithium hydroxide,
whereas the vegetable oil (canola oil) are triglyceride of
fatty acid/esters and possesses some label of polarity and
may be reactive at elevated temperature. These oils even
may have tendency to self-polymerize or react with fat or
alkali to form undesirable polymeric product. However
no efforts have been made to study intricacies of the
reaction pathways. In view of thermal degradation nature
of vegetable oils at elevated temperatures the cooking
temperature of grease was reduced from 400± 5°F (204±
5°C) to 350 ± 5°F (175 ± 5°C). This has given product
with better appearance and the resultant properties of the
grease are tabulated in table-i under lithium 1 2-hydroxy
grease (modified process). Table-i indicates that the end
product resulted into NLGI 2 consistency with i4.5%
soap compared to 18% with conventional process. The
product indicated improved mechanical stability (+ 39
change after 100,000 double strokes) when compare to
+69 unit change for the product that was produced by
conventional processes. However, the grease was still
inferior to mineral oil based lithium 12 hydroxy stearate
grease. Nevertheless, this grease still shows storage
hardening when tested over a period of one year. The
grease hardened about 25 units in one year.
3.2 Closed Kettle (Contractor) Process:
Efforts were made to manufacture the grease in
contactor both mineral oil based and canola oil based
grease. The process adopted to make lithium grease in
contactor involve following steps.
I. Charging the ingredients:
a. Mineral /synthetic base oil (30-50%) is
charged in the kettle
b. Charge fatty acid (12 HSA), lithium hydroxide
and water
II. Cooking:
a. Heat slowly by continuously stirring to
about 400 ± 5°F (204± 5°C) under controlled
pressure
III. Dehydration and Cooling:
a. Cool the grease for few degrees by quench and
rinse process and transferred to finishing kettle
b. Dehydrate the grease to remove moisture
c. Cool the mass is to C17H35C02A1O2CC6H5 ± 3(CH3)2CHOH
parameter like temperature, time, pressure,
OH
quantity of water and agitation. Out of many
combinations one of the compositions with
Subsequently, the better process and a substituted
15.5% soap in open kettle gave rise to satisfactory lithium
trimer of Aluminum isoprop oxide has been developed
complex grease. This grease was additized with ashless
which
is being successfully used to make this class of
EP-Antiwear and oxidation inhibitors. The test results
greases. The aluminum trimer has the advantage of
are tabulated in table 3. Careful analysis of the test data
producing less amount of isopropyl alcohol and can
indicate that the difference between the lithium complex
potentially be made in open kettle.
grease prepared in open kettle process is that the higher%
of soap (15.5%) has been used to make same consistency
grease as compared to mineral oil based grease. Other
considerable difference is the tendency of canola oil
based grease to harden over time, however the extent
of hardening does not seem as pronounced as in case
on canola oil based lithium 12 hydroxy grease prepared
31 NLGI SPOKESMAN, NOVEMBER/DECEMBER 2014
NLGI~
ocH (cH3)~
Al
Figure 4; Trioxyaluminum triisopropoxide Cyclic Trimer
0
0
The mineral oil based grease was prepared by charging mineral
base oil in kettle (60-70%) and then benzoic acid and stearic acid are
H~~~HCOM
A10cH(CTh)2
added, heated till melting and then Trioxyaluminum triisopropoxide
/
Cyclic Trimer was added. The mass was slowly heated to 390-400°F
0
(190-200°C). The progress of the reaction was monitored by FT-JR
(figure-4). FT-JR spectra of both mineral oil and canola oil based indicate band 1605 cm-i, 1587
cm-i and 1566 cm-i indicating the formation of aluminum complex soap thickener, otherwise
there was not much of noticeable change in FT-JR spectra of aluminum complex grease when
compared to just the mineral or canola oil.
Figure-5
The products were then cooled, doped with requisite additives and milled. The grease exhibited
the characteristics as indicated in table-4. The bio-based grease produced by conventional method
was very stringy compared to mineral oil based grease that was translucent and smooth. In
addition, bio-based grease was much softer than mineral oil based grease, NLGJ 1 versus NLGJ
2, although it contained higher percentage of thickener, 18-19% versus 10-11%. The mechanical
stability and roll stability of the resultant grease were quite poor +74 and + 58 unit change
respectively in penetration after 10,000 strokes as compared to only +35 unit change with mineral
oil based grease. Interestingly this grease did not harden over time when tested for storage stability
over a period of 1 year, though lot of oil separation was observed. The processing parameters
were further optimized and reaction temperature was reduced to 320-330°F (160-165°C) and the
stoichiometric ratios were further optimized. The resultant product using improved process and
composition gave rise to acceptable product. The test data of finished grease are tabulated in table4 as aluminum complex grease (modified process). The grease prepared with improved process
– 32 VOLUME 78, NUMBER 5
NLGI
exhibited improved mechanical and roll stability as compared to the grease prepared in
canola oil with conventional process and inferior to the mineral oil based grease. The
storage stability test of this grease over periods of 1 year showed hardening tendency but
less oil separation compared to the grease prepared with conventional process.
6.0 Conclusions:
The lubricating greases based on bio-based fluids are gaining increasing application in
the industry. These greases are either based on lithium, lithium complex, calcium, clay, and
aluminum complex etc. based. One would expect the manufacturing of these greases to be
the same as that of mineral and synthetic oil based greases. However, the studies presented
in this paper indicate significant change in the processing parameters is required. The
problem is that the vegetable oils decompose and polymerize at higher temperatures used
in manufacturing of mineral oil and/or synthetic fluid based greases. This is attributed due
to the fact that that chemistries of mineral and vegetable oils significantly differ. Lowering
the temperature of reaction does have significant impact of the properties of the resultant
grease and lower yield. The hardening of grease overtime also gives an indication of either
incomplete reaction or some side chain reaction. This study indicate that manufacturing
technology of bio-based greases, meeting industry standards, is still at infancy state and
more attention is needed to streamline the manufacturing technologies of these type of
greases.
7.0 Acknowledgement:
Authors gratefully acknowledge the help and guidance provided by Dr Cathy Mallory in
finalizing this manuscript. Authors are thankful to grease plant personnel especially Monte
Walton and Jimmy Koetter in helping to get samples ready.We are also thankful to Mr. Craig
Copper for his help in running FT-JR spectrum of the greases.
8.0 References:
[1] Boner, C. J., “Manufacturing and Applications ofLubricating Greases” Reinhold
Publishing Corp., 430 Park Ave. NY, 1954, pp 136-138.
[2] Polishuk, A. T., ‘~A BriefHistory ofLubricating Greases” Llewellyn & McKane Inc. PA,
1998, pp. 35-72
[3] NLGI, “Lubricating Grease Guide” Published in Kansas City, Missouri, 2006, pp. 11.
[4] NLGJ, “Grease Production Survey Report” Kansas City, Missouri, 2011.
[5] Marietta Ellis; www.alcasoft.com/soapfact/historycontent.html
[6] Miller, George W, “Lubricating Grease” Lubrication Engineering, 7, 2 February, 1951
[7] Hamill, Alexander, USP 38,822, June 9, 1863
[8] Lawrence, A.S.C., “Lubricating Grease” J. Institue of Petroleum, 31, 260, pp. 303-314,
1945
[9] Honary, L., “Bio-based lubricants and greases” Wiley publication, PP. 160 (2011)
[10] Petrovic, Z.S., “Phenolation of vegetable oil” J.Ser.Chem.Soc. 76(4) 59 1-606, 2011
[11] Petrovic, Z.S., “Polymerization ofsoyabean oil with superacids” www.intechopen.com
[12] www.vegetableoilbasedpolymers.wikispaces.com
[13] www.stratcoinc.com
– 33 NLGI SPOKESMAN, NOVEMBER/DECEMBER 2014
Characteristics
Table-i:
Comparative
Test Data of
Lithium 12
Hydroxystearate
1
Greases Prepared
in Open Kettle
2.
Appearance and
texture
Base oil type
1
Thickener
4.
~
6.
7.
%ofthickener
NLGI Grade
DropPoint,°FPC
Viscosity @40 C
,cSt
8. Weld load, kg
9. Tiniken OK load.
lbs
10. Rust Test
ii. Storage Stability
12. Work Penetration
at finishing
Change after lOOK
double strokes
After48 His
After 1 week
After 1 Month
After 6Months
After 1 year
Table-2:
Comparative
Properties
of different
Lithium 12
Hydroxystearate
Greases
Prepared in
Closed (Stratco)
Process
Characteristics
Test Method
Lithium l2hydroxy
stearate grease
Visual
Smooth
Li42-Hydroxy
Stearate
14,5%
2
+350/180°C
+350/180°C
36
36
250
45
250
–
250
45
ASTM 1) 1743
ASTM D 217
Pass
Pass
Pass
285
321
290
+32
±69
±39
287
284
285
284
285
301
296
281
276
Test Method
Lithium 12
hydroxy stearate
grease
Visual
Smooth
288
272
284
282
266
265
Lith. 12 hydroxy
grease
( Conventional
Contactor Process)
Stringy and lumpy
Lith. 12 hydroxy
stearate grease
(Modified Process)
Canola oil
Canola oil
Lithium 12
Hydroxy
Lithium 12 Hydroxy
Hydroxy
–
9.5%
15.0%
13.5%
2
0
2
Base oil type
–
15.
Thickener
–
1~
%ofthickener
1~
NLGI Grade
ASTM D 217
18.
19.
DropPoint,°F/~C
Viscosity~40C
,cSt
Weld load, kg
ASTMD2265
ASTMD44S
22.
21
24.
Li-l2-Hydroxy
Stearate
18%
1
ASTM D 2596
ASTM 2509
–
1~
Timken OK load,
lbs
Rust Test
Storage Stability
Work Penetration at
finishing stage
Changeafter lOOK
double strokes
After 48 His
After iweek
After I Month
After 6 Months
After lyear
Canola oil
Amber fany other
color
Canola oil
ASTM D 217
ASTMD2265
ASTM D 445
–
Appearance
21.
Lith. 12 hydroxy
stearate grease
(Modified Process)
NaphthenicParaffinic Blend
Li-12-Hydroxy
Stearate
12%
2
+350/l80~C
220
–
13.
20.
Lith. 12 hydroxy
stearate grease
( Conventional
Process)
Stringy
NaphthenicParaffinic Blend
Lithium 12
—
350/180
150
250/120
36
Smooth and tacky
±
350/180
36
ASTM D 2596
250
–
315
ASTM 2509
45
–
45
ASTM D 1743
ASTM 1) 217
Pass
–
Pass
281
362
292
-‘-26
±61
±37
280
231
279
278
280
331
326
285
279
321
272
320
322
266
256
Table-3: Comparative Properties of different Lithium Complex Greases
Characteristics
1
2.
Lithium complex grease
( Open Kettle Process)
Oil type
Lithium complex grease
( Closed kettle Process)
Mineral oil based
Canola oil based
Mineral oil based
Canola oil based
Smooth,
translucent
13.5%
Smooth, opaque
15i%
Smooth,
translucent
11.5%
2
2
1
2
3.
Appearance and
texture
%ofthickener
4.
NLGIGrade
5.
DropPoint,°F/°C
+503/261
485/254
517/266
482/252
6.
Viscosity @40 C
,cSt
Storage Stability
Initial Work
Penetration
Changeafter lOOK
double strokes
After 1 week
After lMonth
AfteróMonths
150
36.5
150
36.5
288
275
281
294
+34
+38
+28
+43
284
285
286
272
270
268
280
282
278
284
276
267
7.
creamy opaque
,
16.5%
Table-4: Characteristics ofDifferent Aluminum Complex Greases
Characteristics
Smooth translucent
Naphthenic
Al-complex grease
( Conventional
Process)
Stringy
Canola oil
ASTM D 217
10-11%
2
18-19%
1
17-18%
2
DropPoint,UF/~C
ASTMD226S
±500/260
±500/260
±500/260
6.
Roll stability, 2 hrs
ASTM D 1831
±25
±58
±38
7.
Penetration after 10
K strokes
Storage Stability
Initial Work
Penetration
After 48 His
After 1 week
After 1 Month
After6Months
After 1 year
ASTM D 217
±35
±74
±43
296
387
302
294
293
288
284
282
367
372
296
292
366
285
370
369
280
279
1.
2.
Appearance
Base oil type
I
4.
%ofthickener
NLGI Grade
5.
8.
Test Method
Visual
–
–
Aluminum complex
grease
,
– 35 NLGI SPOKESMAN, NOVEMBER/DECEMBER 2014
Al- complex grease
( Modified Process)
Smooth tacky
Canola oil