COLD ROLLING OILS
Mar 29, 2015
COLD ROLLING OILS
• Introduction• Mechanism of Roll
Lubrication• Requirements of a
Rolling Oil• Trends
(Past/Present/Future)
• Evaluations of Rolling Oil
• Our Lab Mill Trials at RDCIS
• Emulsion Management
• Popular Brands of Rolling Oils in India
• Rolling Mills in India
• Rolling Oil Potential
Contents
Cold Rolling Oil
An Oil / Emulsion introduced at the Roll-bite in the process of Cold Rolling to control Friction at the interface of Work Rolls and Strip
Various Processes in Steel Rolling
Type of Cold Rolling Mills
Why Cold Rolling?• Limitation of HSM to
produce thinner gauge with– Superior surface finish – desired mechanical &
metallurgical properties
• Potential application of the product in consumer goods industry
• Newer cold rolled products are being continuously developed both in bare & coated variety
Type of Cold Rolling Mills
2 Hi Mill • Suitable for hot or cold rolling of ferrous and nonferrous metals.
• Ideal for breakdown, run down, tempering and skin pass operations.
Type of Cold Rolling Mills
4 Hi Mill
Undesirable contact area results in a bending force which causes edge drop.
Type of Cold Rolling Mills
4 Hi Mill • Used both as Non-reversing Mills for intermediate rolling and as Reversing Mills for finish rolling
• Smaller rolls reduce thickness of metal being rolled more easily and with much less pressure than large rolls of a 2-High Mill
• This decreased pressure reduces roll bending and separating forces and permits rolling of wider and thinner materials with a more uniform gauge
• 4-hi mills are a cost-effective means for industry to product a wide range of sheet products . 90% of Mills are of this type.
Type of Cold Rolling Mills
Reversing Mills
Advantages
1. Less Capital Cost
2. Occupy less space
3. Any required gauge can be obtained
Disadvantages
1. Low output
2. High Roll Consumption
Continuous Mills
Advantages
1. Suitable for large outputs
2. Higher gauge accuracy
Disadvantages
1. High capital cost
2. Large production of one size product
Type of Cold Rolling Mills
4 Hi Tandem Mill
Type of Cold Rolling Mills
• Provide improved flatness due to their workroll bending mechanism and intermediate roll adjustment in an axial direction.
• Main advantages are improved shape of rolled strip, increased reductions and greater rolling efficiency.
6 Hi Mill
Drawbacks :• Complicated and hard to maintain roll cluster
unit• Cooling problems resulting from the smaller
circumferential area of their working rolls.
• Undesirable contact area is virtually eliminated by shifting the intermediate rolls axially.
• This can be done quickly and easily, making the HC-MILL the ideal solution for the real world.
• Use of the HC-MILL not only significantly improves quality, but has significant ramifications for the system.
Type of Cold Rolling Mills
6 HI Mill
Type of Cold Rolling Mills
20 Hi Mill
Type of Cold Rolling Mills
20 Hi Mill
Tandem Mill – Continuous Mill
• Modern Tandem Cold Mill consists upto 6 sets of independently driven pairs of Work rolls, each pair being supported by a large no. of back-up rolls
• Cumulative Mill reduction could be in the range of 50% - 90%
• Ensures high gauge accuracy and proper flatness
• Roll separating force involved in rolling 1250 mm wide strip may be as high as 1000T
Mechanism of Roll Lubrication
• Friction is a necessity as a transmitter of Deformation Energy
• Optimization of friction – Adequately high to
Ensure traction in the Roll bite
– Low enough to optimize Mill Motor Power requirement
Mechanism of Roll Lubrication
Oil Pooling at the Bite• Positive Pressure gradient
at the inlet zone• Viscous component of the
oil diffuse more in the roll bite
• Higher Strip temperature (120 -200 oC) evaporates water in emulsion
• Fatty substance affinity to the strip/roll surface
Mechanism of Roll Lubrication
• Vo>Vp>Vi• At neutral Point
Vx=Vp• Contact angle is
about 3-4 Degrees only
• Pressure on the rolls buildup from entry to the neutral point and then declines till exit.
Mechanism of Roll Lubrication
• Lubrication Regimes in– Pre-deformation
Zone•Elasto
Hydrodynamic
– Deformation Zone•Plasto
Hydrodynamic•Boundary•EP Lubrication
Some Important Formulae
dd{(2K p)y} ( )Rp0
y tf2
R2
2 ti tf
R
p2K
Cy2Re
where
2 Rtftan
1 Rtf
p2K
Cy2Re
where
2 Rtftan
1 Rtf
Some Important Formulae
(p2K)before
2yti(1
x
2K)e
( i )
and
(p2K)after
2ytf(1
x
2K)e
(p2K)before
2yti(1
x
2K)e
( i )
and
(p2K)after
2ytf(1
x
2K)e
Pressure Distribution
hfilm 6Vyieldtan
(1 2r3)
Functions of a Cold Rolling Oil
• Lubrication:– Control friction,
wear and surface damage of rolls and strip
• Scavenging:– Heat– Dirt– Wear Debris
Requirements of a Rolling Oil Optimum lubricity,
high film strength, shear stability, high plate-out characteristics
High heat transfer co-efficient
Optimum Emulsion stability/Good chemical stabilityLong emulsion
lifeEasy maintenance
High cleanliness properties Good Burn off
characteristicsGood emulsion
detergencyMinimum soap
formation Easy disposal
Environment friendliness
Bio-degradable
Additional Requirements of a Rolling Oil
Good rust/corrosion protection capacity Good resistance to tramp oil
contamination Easy removability after rolling Complete System Compatibility
Rolling Mill & Strip ComponentsPickling Oil/acid traces carry over
from pickling line Economical
Constituents of Cold Rolling Oils
• Lubricant Base (80% - 90%)– Natural Oils– Fats & their Derivatives– Mineral Oils– Synthetic Esters
• Boundary Additives– Molecules with permanent
dipole moment like Derivatives of Fatty Oils (acids, alcohols, amines)
– Long chain acids are preferred
– Neutral soaps of Esters
Constituents of Cold Rolling Oils
• EP & AW Additives– Chlorinated Paraffins– Sulfurized Mineral
Oils/Fats– Chloro-sulphides– Sulfur-phosphorus
compounds– Nitrogen-phosphorus
compounds
• EmulsifiersHLB ValueEmulsion stabilityOil Particle SizePlate OutShear Stability
• Dispersant / Surfactants
Properties of Rolling Oils• Viscosity
– Higher Film thickness Viscosity• Saponification Value
– Indicates amount of Esters present– Higher SAP value means better lubricity– Higher SAP may impair Cleanliness
behavior of oil• Free Fatty Acid (FFA)
– Help decreasing friction due to adsorption on strip & roll surface thus provide good boundary lubrication
– Prone to oxidation, polymerization and formation of sticky deposits on storage.
– Affects Cleanliness behavior of oil
• Iodine No.– Indicates degree of un-saturation of fatty
materials/esters• Pour Point
– Lower value is desired– May help cooling efficiency– Too low pour oils using short chain compounds
may possess poor lubricity & load bearing ability• pH Value
– Vital for emulsifier’s effectiveness– Affected by
• Carryovers from pickling lines• Water Quality• Tramp Oils• Degeneration/Oxidation of the Rolling Oil
itself
Properties of Rolling Oils
Properties of Rolling Oils• Ash Content
– Low ash formulations are preferred
• Oil Particle Size– Greatly affects Lubricity, Plate-out,
Iron Content of emulsion– Indication of shear stability of the oil
ParametersSheet Rolling
Tin Plate Rolling
Mean Particle Size, µ 2 - 5 3.5 - 10
ESI,% 80 - 90 50 - 95
Oil Plate-out, mg/m2 350 - 600 500 - 1100
Iron Content, ppm 0 - 300 100 - 700
Trends
Palm Oil
Natural Oil/ Fats/
Derivatives
Fatty Oils & Mineral Oils
Synthetic Esters
High
Mol
. Wt.
Polym
ers
Evaluations of Rolling Oils
• Laboratory Tests– Physico-chemical Tests– Functional Tests
• Tribological Tests• Lab. Mill Trial• Industrial Trials
Laboratory Tests of Rolling Oils Physico-chemical Tests
1. Ash Content, % Wt
2. Carbon Residue, CCR, % Wt3. Flash Point, COC, oC4. Free Fatty Acid, Oleic %5. Iodine Number 6. Kinematic Viscosity, @ 40
oC, cSt7. pH of 2% Emulsion in
Distilled Water 8. Pour Point, oC9. Saponification Value, mg of
KOH/gm
Laboratory Tests of Rolling Oils Functional Tests
1. Burn-Off Characteristics
2. Emulsion Stability Index
3. Mean Particle Size, µm
4. Plate-out Characteristics
5. Cleanability6. Iron Corrosion7. HLB Value8. Staining Tendency
Tribological Test Rigs
Test Contact Configuration
Type of Contact
Soda Pendulum
Pin on Two Pairs of Balls
Point Contact
Amsler Wear Test
4 Pairs of Crowned Discs
Line Contact
SRV Test Rig Ball or Roller on Disc Point/Line Contact
LFW1 Rig Ring on Block Line Contact
Ring Compression Test
Ring on Platen Surface Contact
Plint Tribometer
Pin on Sheet Line Contact
Tribological Test Rigs LFW 1 Oscillating Test
Test Description
A steel block pressed against a lubricated oscillating ring.
Test Result Static and dynamic friction coefficient µ, wear in mm, life time of lubricant
Standards ASTM D 2714, ASTM D 2981, ASTM D 3704
Tribological Test Rigs LFW 1 Rotating Test
Test Description
A steel block pressed against a lubricated rotating ring.
Test Result Static and dynamic friction coefficient µ, wear in mm, life time of lubricant
Standards ASTM D 2714, ASTM D 2981, ASTM D 3705
Tribological Test Rigs Falex Pin & Vee Block Tester
Test Description
A lubricated, rotating steel shaft between two V-shaped steel blocks under specified load.
Test Result Friction coefficient µ, wear in mm, endurance life in h, load carrying capacity N
Standards ASTM D 2670, ASTM D 2625, ASTM D 3233, ASTM D 3704
Tribological Test Rigs Falex Pin & Vee Block Tester
Tribological Test Rigs Falex Pin & Vee Block Tester
Tribological Test Rigs SRV Tester
Tribological Test Rigs SRV Tester
Test Description
Measure friction and wear under oscillatory or rotational motion.
Test Result Coefficient of friction µ, wear rate in mm
Standards DIN 51834, ASTM D 5706-7, DIN 50324
Tribological Test RigsFour Ball Machine
Test Description
Wear properties and weld load of consistent lubricants in a four ball system (rotating ball on three fixed balls).
Test Result Welding load in N, wear scare in mm
Standards DIN 51350
Tribological Test Rigs Amsler Wear Test
Tribological Test Rigs Amsler Wear Test
PIN ON DISC TRIBO TESTER
Plint Tribometer
Emulsion Management
Good emulsion management provides
– Consistent performance of oil
– Longer emulsion life
Emulsion Management
What all to manage of an emulsion?1. Concentration2. Temperature3. pH4. Conductivity5. Oil Particle Size (OPS)6. Tramp Oil7. Iron fines8. Bacterial Count
Emulsion Concentration
Variations in actual production line may be high owing to:
– Disproportionate Oil addition– Evaporation of Water– Change in emulsion characteristics of oil– Skimming of tramp oil
•Online oil concentration measurement helps – The oil content directly relates to the velocity
of sound in the fluid. A change of 1% oil content brings about an change of approx. 2 m/s.
Emulsion Temperature
Higher emulsion temperature than desired
– Brings down oil film thickness by decreasing viscosity
– Declines Cooling Efficiency– Emulsifier’s behavior may get affected
Normally kept within 45 – 55oC
Emulsion pH
Emulsifier system is pH sensitiveCauses of pH disturbances
– Acid carry over from pickling line– Inferior feed water for emulsion– Tramp Oil mixing
• Preferred pH range: 5.0 – 7.0
pH < 5.0Increase Particle sizeCorrosion ProblemErratic Rolling
pH > 7.0Reduce Particle sizeMore metallic soaps Affects cleanliness
Emulsion Conductivity
Major contributors: H+, OH-, Cl-, SO42-
Minor Contributors: Ca2+, Mg2+, Na+, K+
Conductivity of Emulsion < 200 µS/cm
Should never exceed 500 µS/cm
Conductivity of – De-mineralized Water < 10 µS/cm– Industrial Hard Water < 500 µS/cm
Tramp Oil
Oil in emulsion that doesn't derive from the emulsion concentration itself is uncontrollable and therefore undesirable.
•Sources of tramp oil – oil leaks from transmissions,
hydraulic systems and other lubrication points
Negative effects of Tramp Oil
• Loss of cooling & wetting properties • Deplete emulsifiers• Nullifying rust-inhibitors • Cuts off air and thereby provides an
excellent base for growth of anaerobic bacteria• Reduce amount of sulfur additives • Drop in pH • Create bad smell• Low pH increases ionization of heavy
metal in coolant and this in turn may create unhealthy working atmosphere.
Desired Values of Some Important Emulsion Parameters
Parameters Desired Value1 Chloride in Pickling Rinse
Water< 60 ppm
2 Chloride on Pickled Strips < 0.03 mg/ft2
3 Emulsion Conductivity < 500 mS/cm2
4 Hardness of Water < 250 ppm
5 Bacteria < 5 x 106 counts/ml
6 Yeast < 200 counts/ml
7 Tramp Oil < 20 - 30 %
8 Iron in Emulsion < 200 ppm
9 pH Variation + 0.5 - 1.0
10
Iron on CR Strip < 100 mg/m2
11
Oil on CR Strip < 100 mg/m2
12
Carbon on Annealed Strip < 7 mg/m2
Emulsion Management
FFA Usually lower than Fresh
Oil as some FFA are lost due to soap formation with Iron & hard water salts
Lowered due to Mineral Oil Contamination
May increase due to excessive bacterial activity
Analysis of Used Extracted Oil
Emulsion Management
SAP Value Lowered with
contamination of Tramp Oils
% drop Indicates reduction of the active oil in emulsion
Should not fall below 70%
IR Spectroscopy– Predicts Ester content &
Fatty acid concentration– Identify contamination
Analysis of Used Extracted Oil
Cold Rolling Mills in India
No. of unit
s
Unit Capacity
(TPA)
Width Range (mm)
Total capacity
20 up to 30,000 upto 450 240,000
16 up to 72,000 450-700 570,000
15 up to 300,000
700-1250 1,420,000
5 up to 300,000
1250-1560 1,310,000
2 > 1,000,000 > 1560 2,690,000
Total 6,230,000
Rolling Oil Potential in India
Specific Rolling Oil consumption in Cold Rolling:
1.2 kg/T of Rolled Sheet for Mineral Oils
0.6 kg/T of Rolled Sheet for Semi-synthetic/Synthetic Oils
Considering the above, Cold Rolling Oil potential would be about 3500 – 5000 KL per Annum
Popular Cold Rolling Oils
Manufacturer
Brand Name
D A Stuart Rolkleen 1000, 2000, 3000
Quaker Chemicals
Quakerol CA 29
B&L Balmerol Aquaroll 431, 432
Indian Oil Servo Steerol C4, C6
HPCL HP Cold Rolling Oil
Houghton Houghto-Roll