Presentation on theme: "COLD ROLLING OILS. Introduction Mechanism of Roll Lubrication Requirements of a Rolling Oil Trends (Past/Present/Future) Evaluations of Rolling Oil Our."— Presentation transcript:
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 o C) 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
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 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
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
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 Emulsifiers HLB Value Emulsion stability Oil Particle Size Plate Out Shear 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 emulsifiers effectiveness – Affected by Carryovers from pickling lines Water Quality Tramp Oils Degeneration/Oxidation of the Rolling Oil itself 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 Parameters Sheet Rolling Tin Plate Rolling Mean Particle Size, µ2 - 53.5 - 10 ESI,%80 - 9050 - 95 Oil Plate-out, mg/m 2 350 - 600500 - 1100 Iron Content, ppm0 - 300100 - 700
Trends Palm Oil Natural Oil/ Fats/ Derivatives Fatty Oils & Mineral Oils Synthetic Esters High Mol. Wt. Polymers
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, % Wt 3.Flash Point, COC, o C 4.Free Fatty Acid, Oleic % 5.Iodine Number 6.Kinematic Viscosity, @ 40 o C, cSt 7.pH of 2% Emulsion in Distilled Water 8.Pour Point, o C 9.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.Cleanability 6.Iron Corrosion 7.HLB Value 8.Staining Tendency
Tribological Test Rigs TestContact Configuration Type of Contact Soda PendulumPin on Two Pairs of BallsPoint Contact Amsler Wear Test4 Pairs of Crowned DiscsLine Contact SRV Test RigBall or Roller on DiscPoint/Line Contact LFW1 RigRing on BlockLine Contact Ring Compression Test Ring on PlatenSurface Contact Plint TribometerPin on SheetLine 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 SRV Tester
Test Description Measure friction and wear under oscillatory or rotational motion. Test ResultCoefficient of friction µ, wear rate in mm StandardsDIN 51834, ASTM D 5706-7, DIN 50324
Tribological Test Rigs Four 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
PIN ON DISC TRIBO TESTER
Emulsion Management Good emulsion management provides – Consistent performance of oil – Longer emulsion life
Emulsion Management What all to manage of an emulsion? 1.Concentration 2.Temperature 3.pH 4.Conductivity 5.Oil Particle Size (OPS) 6.Tramp Oil 7.Iron fines 8.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 – Emulsifiers behavior may get affected Normally kept within 45 – 55 o C
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 < 5.0 Increase Particle size Corrosion Problem Erratic Rolling pH > 7.0 Reduce Particle size More metallic soaps Affects cleanliness
Emulsion Conductivity Major contributors: H +, OH -, Cl-, SO 4 2- Minor Contributors: Ca 2+, Mg 2+, 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 ParametersDesired Value 1Chloride in Pickling Rinse Water< 60 ppm 2Chloride on Pickled Strips< 0.03 mg/ft 2 3Emulsion Conductivity< 500 mS/cm 2 4Hardness of Water< 250 ppm 5Bacteria< 5 x 10 6 counts/ml 6Yeast< 200 counts/ml 7Tramp Oil< 20 - 30 % 8Iron in Emulsion< 200 ppm 9pH Variation+ 0.5 - 1.0 10Iron on CR Strip< 100 mg/m 2 11Oil on CR Strip< 100 mg/m 2 12Carbon on Annealed Strip< 7 mg/m 2
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 units Unit Capacity (TPA) Width Range (mm) Total capacity 20up to 30,000upto 450240,000 16up to 72,000450-700570,000 15up to 300,000700-12501,420,000 5up to 300,0001250-15601,310,000 2> 1,000,000> 15602,690,000 Total6,230,000
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 ManufacturerBrand Name D A StuartRolkleen 1000, 2000, 3000 Quaker Chemicals Quakerol CA 29 B&LBalmerol Aquaroll 431, 432 Indian OilServo Steerol C4, C6 HPCLHP Cold Rolling Oil HoughtonHoughto-Roll