COLD ROLLING OILS

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COLD ROLLING OILS
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Contents

• Our Lab Mill Trials at RDCIS
• Emulsion Management
• Popular Brands of Rolling Oils in India
• Rolling Mills in India
• Rolling Oil Potential

• Introduction
• Mechanism of Roll Lubrication
• Requirements of a Rolling Oil
• Trends (Past/Present/Future)
• Evaluations of Rolling Oil

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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

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Various Processes in Steel Rolling
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Type of Cold Rolling Mills
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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

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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. 

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Type of Cold Rolling Mills
4 Hi Mill
Undesirable contact area results in a bending
force which causes edge drop.
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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.

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Type of Cold Rolling Mills

• Reversing Mills
• Advantages
• Less Capital Cost
• Occupy less space
• Any required gauge can be obtained
• Disadvantages
• Low output
• High Roll Consumption

• Continuous Mills
• Advantages
• Suitable for large outputs
• Higher gauge accuracy
• Disadvantages
• High capital cost
• Large production of one size product

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Type of Cold Rolling Mills
4 Hi Tandem Mill
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Type of Cold Rolling Mills
6 Hi Mill

• 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.

• Drawbacks
• Complicated and hard to maintain roll cluster
  unit
• Cooling problems resulting from the smaller
  circumferential area of their working rolls.

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Type of Cold Rolling Mills
6 HI Mill

• 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.

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Type of Cold Rolling Mills
20 Hi Mill
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Type of Cold Rolling Mills
20 Hi Mill
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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

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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

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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

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Mechanism of Roll Lubrication

• VogtVpgtVi
• At neutral Point VxVp
• Contact angle is about 3-4 Degrees only
• Pressure on the rolls buildup from entry to the
  neutral point and then declines till exit.

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Mechanism of Roll Lubrication

• Lubrication Regimes in
• Pre-deformation Zone
• Elasto Hydrodynamic
• Deformation Zone
• Plasto Hydrodynamic
• Boundary
• EP Lubrication

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Some Important Formulae
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Some Important Formulae
Pressure Distribution
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Functions of a Cold Rolling Oil

• Lubrication
• Control friction, wear and surface damage of
  rolls and strip
• Scavenging
• Heat
• Dirt
• Wear Debris

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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
  stability
• Long emulsion life
• Easy maintenance

• High cleanliness properties
• Good Burn off characteristics
• Good emulsion detergency
• Minimum soap formation
• Easy disposal
• Environment friendliness
• Bio-degradable

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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 Components
• Pickling Oil/acid traces carry over from pickling
  line
• Economical

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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

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Constituents of Cold Rolling Oils

• Emulsifiers
• HLB Value
• Emulsion stability
• Oil Particle Size
• Plate Out
• Shear Stability

• Dispersant / Surfactants

• EP AW Additives
• Chlorinated Paraffins
• Sulfurized Mineral Oils/Fats
• Chloro-sulphides
• Sulfur-phosphorus compounds
• Nitrogen-phosphorus compounds

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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

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Properties of Rolling Oils

• 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 emulsifiers effectiveness
• Affected by
• Carryovers from pickling lines
• Water Quality
• Tramp Oils
• Degeneration/Oxidation of the Rolling Oil itself

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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

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Trends
Palm Oil
Natural Oil/ Fats/ Derivatives
High Mol. Wt. Polymers
Fatty Oils Mineral Oils
Synthetic Esters
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Evaluations of Rolling Oils

• Laboratory Tests
• Physico-chemical Tests
• Functional Tests
• Tribological Tests
• Lab. Mill Trial
• Industrial Trials

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Laboratory Tests of Rolling Oils
Physico-chemical Tests

• Ash Content, Wt
  
• Carbon Residue, CCR, Wt
• Flash Point, COC, oC
• Free Fatty Acid, Oleic
• Iodine Number
• Kinematic Viscosity, _at_ 40 oC, cSt
• pH of 2 Emulsion in Distilled Water
• Pour Point, oC
• Saponification Value, mg of KOH/gm

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Laboratory Tests of Rolling Oils Functional
Tests

• Burn-Off Characteristics
• Emulsion Stability Index
• Mean Particle Size, µm
• Plate-out Characteristics
• Cleanability
• Iron Corrosion
• HLB Value
• Staining Tendency

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Tribological Test Rigs
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Tribological Test Rigs LFW 1 Oscillating Test
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Tribological Test Rigs LFW 1 Rotating Test
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Tribological Test Rigs Falex Pin Vee Block
Tester
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Tribological Test Rigs Falex Pin Vee Block
Tester
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Tribological Test Rigs Falex Pin Vee Block
Tester
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Tribological Test Rigs SRV Tester
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Tribological Test Rigs SRV Tester
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Tribological Test RigsFour Ball Machine
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Tribological Test Rigs Amsler Wear Test
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Tribological Test Rigs Amsler Wear Test
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PIN ON DISC TRIBO TESTER
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Plint Tribometer
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Emulsion Management

• Good emulsion management provides
• Consistent performance of oil
• Longer emulsion life

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Emulsion Management

• What all to manage of an emulsion?
• Concentration
• Temperature
• pH
• Conductivity
• Oil Particle Size (OPS)
• Tramp Oil
• Iron fines
• Bacterial Count

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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.

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Emulsion Temperature

• Higher emulsion temperature than desired
• Brings down oil film thickness by decreasing
  viscosity
• Declines Cooling Efficiency
• Emulsifiers behavior may get affected
• Normally kept within 45 55oC

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Emulsion pH

• Emulsifier system is pH sensitive
• Causes 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 lt 5.0 Increase Particle size Corrosion
Problem Erratic Rolling
pH gt 7.0 Reduce Particle size More metallic soaps
Affects cleanliness
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Emulsion Conductivity

• Major contributors H, OH-, Cl-, SO42-
• Minor Contributors Ca2, Mg2, Na, K
• Conductivity of Emulsion lt 200 µS/cm
• Should never exceed 500 µS/cm
• Conductivity of
• De-mineralized Water lt 10 µS/cm
• Industrial Hard Water lt 500 µS/cm

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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

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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.

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Desired Values of Some Important Emulsion
Parameters
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Emulsion Management
Analysis of Used Extracted Oil

• 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

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Emulsion Management
Analysis of Used Extracted Oil

• 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

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Cold Rolling Mills in India
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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/Synthe
  tic Oils
• Considering the above, Cold Rolling Oil potential
  would be about 3500 5000 KL per Annum

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Popular Cold Rolling Oils
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