2 Contents Our Lab Mill Trials at RDCIS Introduction Emulsion ManagementPopular Brands of Rolling Oils in IndiaRolling Mills in IndiaRolling Oil PotentialIntroductionMechanism of Roll LubricationRequirements of a Rolling OilTrends (Past/Present/Future)Evaluations of Rolling Oil
3 Cold Rolling OilAn Oil / Emulsion introduced at the Roll-bite in the process of Cold Rolling to control Friction at the interface of Work Rolls and Strip
6 Why Cold Rolling? Limitation of HSM to produce thinner gauge with Superior surface finishdesired mechanical & metallurgical propertiesPotential application of the product in consumer goods industryNewer cold rolled products are being continuously developed both in bare & coated variety
7 Type of Cold Rolling Mills 2 Hi MillSuitable for hot or cold rolling of ferrous and nonferrous metals.Ideal for breakdown, run down, tempering and skin pass operations.
8 Type of Cold Rolling Mills 4 Hi MillUndesirable contact area results in a bending force which causes edge drop.
9 Type of Cold Rolling Mills 4 Hi MillUsed both as Non-reversing Mills for intermediate rolling and as Reversing Mills for finish rollingSmaller 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 gauge4-hi mills are a cost-effective means for industry to product a wide range of sheet products . 90% of Mills are of this type.
10 Type of Cold Rolling Mills Reversing MillsAdvantagesLess Capital CostOccupy less spaceAny required gauge can be obtainedDisadvantagesLow outputHigh Roll ConsumptionContinuous MillsAdvantagesSuitable for large outputsHigher gauge accuracyDisadvantagesHigh capital costLarge production of one size product
12 Type of Cold Rolling Mills 6 Hi MillProvide 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 unitCooling problems resulting from the smaller circumferential area of their working rolls.
13 Type of Cold Rolling Mills 6 HI MillUndesirable 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.
16 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 rollsCumulative Mill reduction could be in the range of 50% - 90%Ensures high gauge accuracy and proper flatnessRoll separating force involved in rolling 1250 mm wide strip may be as high as 1000T
17 Mechanism of Roll Lubrication Friction is a necessity as a transmitter of Deformation EnergyOptimization of frictionAdequately high to Ensure traction in the Roll biteLow enough to optimize Mill Motor Power requirement
18 Mechanism of Roll Lubrication Oil Pooling at the BitePositive Pressure gradient at the inlet zoneViscous component of the oil diffuse more in the roll biteHigher Strip temperature ( oC) evaporates water in emulsionFatty substance affinity to the strip/roll surface
19 Mechanism of Roll Lubrication Vo>Vp>ViAt neutral Point Vx=VpContact angle is about 3-4 Degrees onlyPressure on the rolls buildup from entry to the neutral point and then declines till exit.
20 Mechanism of Roll Lubrication Lubrication Regimes inPre-deformation ZoneElasto HydrodynamicDeformation ZonePlasto HydrodynamicBoundaryEP Lubrication
23 Functions of a Cold Rolling Oil Lubrication:Control friction, wear and surface damage of rolls and stripScavenging:HeatDirtWear Debris
24 Requirements of a Rolling Oil Optimum lubricity, high film strength, shear stability, high plate-out characteristicsHigh heat transfer co-efficientOptimum Emulsion stability/Good chemical stabilityLong emulsion lifeEasy maintenanceHigh cleanliness propertiesGood Burn off characteristicsGood emulsion detergencyMinimum soap formationEasy disposalEnvironment friendlinessBio-degradable
25 Additional Requirements of a Rolling Oil Good rust/corrosion protection capacityGood resistance to tramp oil contaminationEasy removability after rollingComplete System CompatibilityRolling Mill & Strip ComponentsPickling Oil/acid traces carry over from pickling lineEconomical
26 Constituents of Cold Rolling Oils Lubricant Base (80% - 90%)Natural OilsFats & their DerivativesMineral OilsSynthetic EstersBoundary AdditivesMolecules with permanent dipole moment like Derivatives of Fatty Oils (acids, alcohols, amines)Long chain acids are preferredNeutral soaps of Esters
27 Constituents of Cold Rolling Oils EmulsifiersHLB ValueEmulsion stabilityOil Particle SizePlate OutShear StabilityDispersant / SurfactantsEP & AW AdditivesChlorinated ParaffinsSulfurized Mineral Oils/FatsChloro-sulphidesSulfur-phosphorus compoundsNitrogen-phosphorus compounds
28 Properties of Rolling Oils ViscosityHigher Film thickness ViscositySaponification ValueIndicates amount of Esters presentHigher SAP value means better lubricityHigher SAP may impair Cleanliness behavior of oilFree Fatty Acid (FFA)Help decreasing friction due to adsorption on strip & roll surface thus provide good boundary lubricationProne to oxidation, polymerization and formation of sticky deposits on storage.Affects Cleanliness behavior of oil
29 Properties of Rolling Oils Iodine No.Indicates degree of un-saturation of fatty materials/estersPour PointLower value is desiredMay help cooling efficiencyToo low pour oils using short chain compounds may possess poor lubricity & load bearing abilitypH ValueVital for emulsifier’s effectivenessAffected byCarryovers from pickling linesWater QualityTramp OilsDegeneration/Oxidation of the Rolling Oil itself
30 Properties of Rolling Oils Ash ContentLow ash formulations are preferredOil Particle SizeGreatly affects Lubricity, Plate-out, Iron Content of emulsionIndication of shear stability of the oilParametersSheet RollingTin Plate RollingMean Particle Size, µ2 - 5ESI,%Oil Plate-out, mg/m2Iron Content, ppm
32 Evaluations of Rolling Oils Laboratory TestsPhysico-chemical TestsFunctional TestsTribological TestsLab. Mill TrialIndustrial Trials
33 Laboratory Tests of Rolling Oils Physico-chemical Tests Ash Content, % WtCarbon Residue, CCR, % WtFlash Point, COC, oCFree Fatty Acid, Oleic %Iodine NumberKinematic 40 oC, cStpH of 2% Emulsion in Distilled WaterPour Point, oCSaponification Value, mg of KOH/gm
34 Laboratory Tests of Rolling Oils Functional Tests Burn-Off CharacteristicsEmulsion Stability IndexMean Particle Size, µmPlate-out CharacteristicsCleanabilityIron CorrosionHLB ValueStaining Tendency
35 Tribological Test Rigs Contact ConfigurationType of ContactSoda PendulumPin on Two Pairs of BallsPoint ContactAmsler Wear Test4 Pairs of Crowned DiscsLine ContactSRV Test RigBall or Roller on DiscPoint/Line ContactLFW1 RigRing on BlockRing Compression TestRing on PlatenSurface ContactPlint TribometerPin on Sheet
36 Tribological Test Rigs LFW 1 Oscillating Test Test DescriptionA steel block pressed against a lubricated oscillating ring.Test ResultStatic and dynamic friction coefficient µ, wear in mm, life time of lubricantStandardsASTM D 2714, ASTM D 2981, ASTM D 3704
37 Tribological Test Rigs LFW 1 Rotating Test Test DescriptionA steel block pressed against a lubricated rotating ring.Test ResultStatic and dynamic friction coefficient µ, wear in mm, life time of lubricantStandardsASTM D 2714, ASTM D 2981, ASTM D 3705
38 Tribological Test Rigs Falex Pin & Vee Block Tester Test DescriptionA lubricated, rotating steel shaft between two V-shaped steel blocks under specified load.Test ResultFriction coefficient µ, wear in mm, endurance life in h, load carrying capacity NStandardsASTM D 2670, ASTM D 2625, ASTM D 3233, ASTM D 3704
39 Tribological Test Rigs Falex Pin & Vee Block Tester
40 Tribological Test Rigs Falex Pin & Vee Block Tester
42 Tribological Test Rigs SRV Tester Test DescriptionMeasure friction and wear under oscillatory or rotational motion.Test ResultCoefficient of friction µ, wear rate in mm StandardsDIN 51834, ASTM D , DIN 50324
43 Tribological Test Rigs Four Ball Machine Test DescriptionWear properties and weld load of consistent lubricants in a four ball system (rotating ball on three fixed balls).Test ResultWelding load in N, wear scare in mmStandardsDIN 51350
48 Emulsion Management Good emulsion management provides Consistent performance of oilLonger emulsion life
49 Emulsion Management What all to manage of an emulsion? Concentration TemperaturepHConductivityOil Particle Size (OPS)Tramp OilIron finesBacterial Count
50 Emulsion Concentration Variations in actual production line may be high owing to:Disproportionate Oil additionEvaporation of WaterChange in emulsion characteristics of oilSkimming of tramp oilOnline oil concentration measurement helpsThe 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.
51 Emulsion Temperature Higher emulsion temperature than desired Brings down oil film thickness by decreasing viscosityDeclines Cooling EfficiencyEmulsifier’s behavior may get affectedNormally kept within 45 – 55oC
52 Emulsion pH Emulsifier system is pH sensitive Causes of pH disturbancesAcid carry over from pickling lineInferior feed water for emulsionTramp Oil mixingPreferred pH range: 5.0 – 7.0pH < 5.0Increase Particle sizeCorrosion ProblemErratic RollingpH > 7.0Reduce Particle sizeMore metallic soapsAffects cleanliness
53 Emulsion Conductivity Major contributors: H+, OH-, Cl-, SO42-Minor Contributors: Ca2+, Mg2+, Na+, K+Conductivity of Emulsion < 200 µS/cmShould never exceed 500 µS/cmConductivity ofDe-mineralized Water < 10 µS/cmIndustrial Hard Water < 500 µS/cm
54 Tramp OilOil in emulsion that doesn't derive from the emulsion concentration itself is uncontrollable and therefore undesirable.Sources of tramp oiloil leaks from transmissions, hydraulic systems and other lubrication points
55 Negative effects of Tramp Oil Loss of cooling & wetting propertiesDeplete emulsifiersNullifying rust-inhibitorsCuts off air and thereby provides an excellent base for growth of anaerobic bacteriaReduce amount of sulfur additivesDrop in pHCreate bad smellLow pH increases ionization of heavy metal in coolant and this in turn may create unhealthy working atmosphere.
56 Desired Values of Some Important Emulsion Parameters 1Chloride in Pickling Rinse Water< 60 ppm2Chloride on Pickled Strips< mg/ft23Emulsion Conductivity< 500 mS/cm24Hardness of Water< 250 ppm5Bacteria< 5 x 106 counts/ml6Yeast< 200 counts/ml7Tramp Oil< %8Iron in Emulsion< 200 ppm9pH Variation10Iron on CR Strip< 100 mg/m211Oil on CR Strip12Carbon on Annealed Strip< 7 mg/m2
57 Emulsion Management FFA Analysis of Used Extracted Oil Usually lower than Fresh Oil as some FFA are lost due to soap formation with Iron & hard water saltsLowered due to Mineral Oil ContaminationMay increase due to excessive bacterial activity
58 Emulsion Management Analysis of Used Extracted Oil SAP Value Lowered with contamination of Tramp Oils% drop Indicates reduction of the active oil in emulsionShould not fall below 70%IR SpectroscopyPredicts Ester content & Fatty acid concentrationIdentify contamination
59 Cold Rolling Mills in India No. of unitsUnit Capacity (TPA)Width Range (mm)Total capacity20up to 30,000upto 450240,00016up to 72,000570,00015up to 300,0001,420,00051,310,0002> 1,000,000> 15602,690,000Total6,230,000
60 Rolling Oil Potential in India Specific Rolling Oil consumption in Cold Rolling:1.2 kg/T of Rolled Sheet for Mineral Oils0.6 kg/T of Rolled Sheet for Semi-synthetic/Synthetic OilsConsidering the above, Cold Rolling Oil potential would be about 3500 – 5000 KL per Annum
61 Popular Cold Rolling Oils ManufacturerBrand NameD A StuartRolkleen 1000, 2000, 3000Quaker ChemicalsQuakerol CA 29B&LBalmerol Aquaroll 431, 432Indian OilServo Steerol C4, C6HPCLHP Cold Rolling OilHoughtonHoughto-Roll