WAR AGAINST CONTAMINATIONBy- Kaushal Kumar Supervisor- Mr. J. K. Dutt2012ME10681Observational Week Backhoe assembly line Engine block manufacturing Quality testing hot testing, testing for contaminationLOGISTICSFABRICATIONSHOPPAINT SHOPMAIN FRAME ASSEMBLY LINE (M - LINE)BACKHOE ASSEMBLY LINE (A - LINE)TWIN SLAT LINE (T- LINE)PDI AND TESTING ZONE(INSPECTION ZONE)GREEN SIGNALTRANSMISSIONLINESKID SUB ASSEMBLY LINERAM PAINTSHOPBOOMDIPPER SUB ASSY. & LOADER ARM SUB ASSY.Figure: Manufacturing unit process layoutProject : putting rust to rest (observational training) PROBLEM STATEMENT: The pipes used in the hydraulics feed has a persistent problem of rusting and contamination AIM: Eliminate contamination and rust in hydraulic circuit pipes SCOPE: To identify probable causes of contamination & rust in supplied hydraulic pipes and take counter measures to eliminate the problemINTRODUCTION TO CONTAMINATION IN HYDRAULIC CIRCUITNeed for Cleanliness: Construction machinery uses a large volume of fluid in the hydraulic system for power transmission, equipment lubrication, rust prevention and sealing. According to a survey conducted by a pump manufacturer, seventy per cent of the causes of problems in hydraulic equipment were attributable to inadequate maintenance of the quality of the hydraulic fluid. So, maintaining proper levels of cleanliness will help prevent hydraulic machinery problems and greatly improve safety and reliability. It also help in improving the life of the hydraulic fluid. Contaminants lead to aloss in the efficiency of the machine which may not be detected by the operator a long time after the loss starts. Contaminants accelerates the component wear and further aggravates the contamination problem.Types of contamination: The contamination can be present in any form- solid, liquid or gas. Solid contamination- sand, fibres, metallic particles, welding scale, sealing materials and wear particles etc. Liquid contamination- - usually water and incompatible oils and greases. Gaseous contamination- - Air, sulphur dioxide etc. which can create corrosive compounds if dissolved in the fluid. These contaminants can appear during manufacture, assembly and operation.TYPES OF CONTAMINANTS Ferrous RUST METAL CHIPS WELD SPATTERSTypes of rust Red rust (Fe2O3.H2O) Yellow rust (FeO(OH).H2O) Brown rust (Fe2O3.H2O) Black rust (Fe3O4.H2O) Non ferrous:Solid -- sand, fibres, sealing materials and wear particles etc. Liquid contamination -- usually water and incompatible oils and greases.Gaseous contamination -- Air, sulphur dioxide The presence of solid contaminants can lead to jamming of the machinery leading to temporary or sudden failure. The presence of gaseous contaminants like air in the hydraulic oil are highly compressible in contrast to the incompressible oil can lead to performance issues because due to compression of the pumped oil which leads to sharp fall in the pressure achieved of the hydraulic oil. Once inside the system, hydraulic circuit contaminants greatly affect the performance and life of hydraulic equipment. For example, contaminants in a hydraulic pump develop internal wear to cause internal leakage and hence lower discharges. Wear particles generated will circulate with the hydraulic fluid to cause further deterioration in the performance of this and other equipment. Contaminants also enter principal sliding sections of the equipment causing temporary malfunction, scuffing, sticking and leakage and can lead to major problems. The contaminants present in the coolant and hydraulic oil to an extent interfere with the heat transfer from the heavy machinery with the outside environment. This can lead to heating of the machine parts which lowers the life of the machine and may lead to catastrophic failure. It can prevent the sealing of oil between the moving parts. This can lead to insufficient thickness of the oil film between the moving rotary parts. The high pressures & friction can damage the surface and lead to catastrophic failures in the machine.EFFECTS OF CONTAMINATION:Cleanliness standards of JCB: ISO 4406 is used for the fine particles standards and is generally 17/15/12 for the parts received while for oils and flushing fluids used are 14/16/11 or better. This are also converted for the gravimetric patch test of the parts in absence of a particle counter. The equivalent NAS level used is NAS 6.For large particulates, ISO 4405 is used. The solid particles present in the part should not be greater than 1000 microns.For the brake components, the parts used in vacuum-bleed assembly need to be completely free of the liquid contaminants. For other brake parts, the liquid contamination should be less than 400mg with a maximum of 200ppm of water. Further, the liquid contamination should be compatible with the seal material.Gravimetric Patch test in JCB:1. Flush the required parts, pack them in polybag and dispatch them to the Quality chemical lab.2. Open the polybag, open one end cap and pour at least 100ml of TCE (tetra chloral ethylene) through this end cap. The solvent is thoroughly shaken and mixed inside the part.3. Finally, this solvent is poured out in (by part) numbered beakers. 4. The 5 microns filter paper is dried in the oven at 82-+- 0.5 degrees Celsius. This is then used with the vacuum suction apparatus to separate the contaminants on the filter paper. The filter paper is again dried at 82+-0.5 degrees Celsius in the oven for pre-specified time. The initial weight of the filter paper is subtracted from the final weight. 5. Final weight of filter paper Initial weight of filter paper = Weight of the contaminants6. The contaminants can be studied under the microscope to check for the large-size particle contamination standard of less than 1000 microns. Parker particle counting machine:Process Flow for the Pipe from supplier to JCB:StoragePipe O/D turningThread rollingCone cuttingPipe bendingDrilling and reamingStub weldingLeakage testingPlating FlushingGravimetribPatch testingDispatchInput (C- controlled, NC- non controlled) Process Output Opportunity for contaminationC- Pipe,Storage conditions, pipe length, packaging, pipe material, pipe supplierNC- check for rust, dent and other defects over period ofstorageStoragePipe of required dimensionsC- pipe length, damages during the storage, environmental conditions during storageNC- storage periodEnvironmental conditions during storagePipe from storageC- Thickness of the pipe, pipe length, cutting tool, feed of pipe, rotating speed of lathe, coolant to be used, use of compressed air gun to remove the chips inside the pipe, use of mandrels or supports NC- temperature of the pipe surfacePipe O/D turning (CNC m/c) C- O/D at the pipe ends within given tolerances, length of the turningNC- exact O/D and length of the pipe, temperature of the tool tip, chips formationChips may get lodged or worse stuck in the pipeTurned pipeC- the oil pressure applied to the rollers, the type of rollers used, the stopper used, the oil usedNC- temperature during the rolling, the forces on pipe during rollingThread rollingC- thread main diameter within given tolerances, thread lengthNC-The oil may not be clean or the filter may be past its use. C- Type of m/c used(lathe or cnc), cone angle setupNC-Cone cutting C- cone angle, cone maximum diameterNC-Chips may get lodged or worse stuck in the pipe, sharp edges left may introduce small bits during useC- oil pressure applied (backside manual), machine used(cnc 5-axis and 3-axis m/c s), fixtures usedNC- the forces applied on the different partsPipe Bending(3-axis and 5-axis CNC m/c)C- profile of the pipe within tolerancesNC- collapsing/dents in pipes, spring back in pipesImproper profile/dents, etc. may lead to cavitation and contamination in the pipesC- the drill bit used, the location for the drillings on the pipe, the coolant used, use of fixturesNC-Drilling of pipes and reaming of the burred edges (this is before bending)C- position of the drilled holes, drill hole sizeNC- burrs, chips formedImproper reaming of pipe for burrsC- constant V, gas composition and flow, current, wire speed, wire size, type of welding (only MIG used)NC-defects introduced by hand held machinesStub Welding C- stub welding positionNC- weld defects like pinholes, spatter, over-welding, undercutImproper contaminated (containing oxygen) gas mixture used, improper shielding by gases, rust/contamination present in the files or chiselC- pressure provided, hydraulic oil used, torque wrench limitNC- testing proof pressure(depending on operating pressure of the part) provided by the customerLeakage testing C- result for the testing for weld defectsNC- do not check for collapsing or dentingof the pipeCan weaken the weld spot and lead to leakage and other problems over its usage lifeWorking training: Fish bone analysis for contamination in pipesFish bone analysis for contamination in pipes: Man: Irregular or inadequate checking of the process parameters during manufacturing and subsequent processing e.g. ph., dc current applied (regular records and audit of those records) Non-compliance of the SOPs (training of SOPs to the workers, writing the SOPs in regional languages) Improper quality check by the inspection workers Capping is not immediate after final flushing (capping immediately after flushing) The caps used should be according to the threads of the pipe (use of rubber caps/colour coding of caps by size) Missed/improper oiling of a part (poke yoke for oiling of pipes) Packaging is not done correctly and allows atmospheric contact (proper airtight packaging) Machine: Improper control of process parameters e.g. improper lathe settings may introduce chips into the pipe, no control of ph. of tanks during the electroplating process, . The tools used may have contamination/rust themselves i.e. contaminated tools (checking of tools regularly) e.g. files used to remove the slag covering on welds Filter used in thread rolling, contamination and flushing tests, etc. may not filter correctly because of no regular checks of filter health or filter change after too long time (data for filter from IAI) (regular check of the filter contamination level) Contamination from the environment due to the work line being open to the outer environment (patch all such places) No or improper regulation of humidity during storage (have a proper storage facility) The compressed air in air guns might carry contaminants and water without any or faulty outer filter or humidity control check (have required facilities) The drier after the electroplating may not completely dry the inside of pipe (blow air from hot blow airs into the balloons) Rust may be present in the electroplating tanks itself (audit the tanks for traces of iron/rust at regular visual inspections and tests) The machining m/c s may introduce chips as contaminants or burrs in the pipes inside (usage of compressed air gun) Method: Inadequate drying of the inside of pipe may lead to rust formation during the time period between transport and further flushing and treatment of the pipe (plugging at ends; blow hot air inside the pipes) FIFO is not followed during the storage of pipes during any stage storage to flushing after returning from the electroplating plant (application of FIFO) Storage of the pipes in unregulated, open environment (better storage facilities) Inadequate packaging and capping of pipes during transport (capping of all open pipe ends) Capping is not immediate after final flushing and application of rust preventive oil (immediate capping) The overall processing of the pipe should insure that pipes are held up for the optimum amount of time (capability study of the pipe processing, optimisation of the pipe operations) MIG welding (semi-automatic) produces a less stable arc than automatic TIG welding. This leads to more defects and weaker unstable welds (use of TIG welding for better results) Material: The materials used pipe, oil, etc. may not be chemically compatible (prior analysis) The supplied materials particular batch may not fulfil the chemical and physical requirements (batch analysis at the suppliers end) The alloyed metal from the supplier may be flawed and prone to rusting (get a report from the supplier end) The caps used from the suppliers end should be according to the threads of the pipe. Soft plastic is not used and it is tightened above a certain limit. This can damage threads leading to leakage and losses in performance (use of rubber caps w/o threads, or proper colour coding of caps) Environment: Storage of pipes at any stage when it is open to environment (proper storage facility) Cleanliness in the work environment is not maintained at the required level (maintaining proper 5s systems for cleanliness) Electroplating or other processes open to environment or sufficient level of cleanliness is not used (identify and rectify) Inadequate packaging and capping of pipes during transport (use poke-yoke to ensure proper packaging)Why-why Analysis/5 whysThe storage in the IAI tube plant led to introduction of contamination and the start of rusting in pipes Storage is open to atmospheric dust and moisture -> the storage does not have proper sealing or regulating system to control the exposure to the environment Storage of pipes is in open crates and poor packaging -> lack of proper bins and shelves Long term storage of pipes ->FIFO is not implemented in storage -> there is no order in the storage of pipes -> no visual documentation about the date of receiving of batch of pipes -> poor administration at the supplier endThe processing of pipes in the electroplating plant caused the start of rusting in the ID of the pipes The chemical treatment in the tank and subsequent drying and dispatch also interact with ID of pipe -> ID does not get electroplated during this process but is treated to same chemicals which makes ID surface active -> unnecessary exposure to chemical of ID of pipe Problem in the drying of the pipe followed by dispatch -> not sufficient time for heater to dry -> inside surface is inaccessible and takes more time to dry than outer surface -> unnecessary exposure to chemical of ID of pipe Possible solutions to the problems: Electroplating the inside surface of the pipes:This can be achieved by any of the following- Auxiliary anode inside the pipe. However this method only works for straight pipes, not for any bent pipe. If we electroplate the straight pipe and then bend it, the outer electroplating will peel from the bending & interaction with the bending pulleys. The inside surface electroplating will flake and cause problem of contamination in the pipe. Hot dip zinc plating. The surface of the plating will be very rough and cause lower performance of the machine. In the future, it will lead to contamination by flaking off from the inside surface. It weakens the high strength steel by hydrogen embrittlement. Brush electroplating. A brush to electroplate the inside of pipe may be designed. However it will have tendency to be thicker at one end and thin at the other. It requires a lot of operator involvement. So it is not desirable to switch to brush electroplating from tank electroplating because tank electroplating requires almost no operator supervision. So this approach does not have any workable solutions in sight.Insulating the pipe inside from the electrolytes in the electroplating tanks using plugs: Because the ID of pipe is not being electroplated, the ends of the pipe can be plugged during the electroplating process of the pipe to prevent the electrolytes from coming into contact with the inside of the pipe. After the drying of the pipes outside surface, the plugs can be removed and reused.Prevent long term storage of pipes: For this, the incoming date of the pipes should be recorded with the batch of pipes. A maximum number of pipes should be set for the different types of pipes in the storage. Pipes with less demand or pipes which are stored for more than one month should be stored with sufficient protection.Failure Modes and Effects Analysis for the pipe processing at IAI (pipe supplier to JCB) end:Process step Requirements Mode of failure possibleCauses of failure Effects of the failure Current process controlsRecommen-ded ActionIncoming material Parts should be as per drawingPart material is not as per drawingNo inspection for material chemical composition and physical parametersCan lead to failure (collapse, leakage, dent) in the part or incompatibility in the machineTechnical reports for the batch from the supplier with each batch, Third party test reports as per the specified testing conditions by IAI--Part dimension is not as per the drawingFaulty standards used or faulty practices by the operatorCan lead to collapse, dent, etc. and may cause holdup of the customer lineSupplier inspection with each lot100% important dimensions check of each pipe when operated upon at IAIStorage The storage conditions should be conducive to protection from contamination and rustThe storage conditions are exposed to atmospheric contaminationThe storage facilities are not constructed wellCan lead to contamination and rusting in the pipesStorage is not regulatedProper sealing of storage from atmosphere FIFO is not maintained in the storage of the pipesThe pipes are stored in very large batches, the pipes are not stored according to the dates they are receivedLong storage of pipes may lead to settling of dust, etc. in the pipes, start of rusting in pipesDate of receiving batch noted Smaller batches of pipes according to the customer demand, storage according to the dateThe storage of pipes is not done properly in the storage bins viz the parts are not properly stacked and coveredThe pipes are stacked haphazardly in the bins Pipes may get scratched, dented, etc. due to rough handlingBins are having stacked pipesSectioning of the storage bins to prevent stacking of pipesMinimum height from the ground is not maintainedStorage racks are of improper model, not taken in considerationMovements in the storage room may lead to settling of dust in the pipesNot implemented Implement a minimum height from ground in the storage racksO/D turning Proper O/D of the turned pipePipe O/D is more or less than the desired O/D sizeM/c setting is improperThreading operation is not proper, leakage in the threaded joints, threaded joints fitment issuesChecking of setting by an operator during start of each turning operation, 100% diameter checking with snap gauges during final inspection--Turning process is improper with burr marks on the surfaceTool piece is worn out, m/c setting (tool feed, RPM of m/c) is not as per specificationImproper threading operation, leakage in threaded jointCNC m/c with provision of program locking, checking for tool regularly, visual inspectionUse of History card for checking tool lifeThread rolling Threading on required parts asper the standard Thread oversize O/D of turned pipe is more, pressurevariation in the thread rollingFitment issues in threaded joints Pressure gauge on thread rolling m/c, check for threads using GO &NO-GO ring gauges for all threadsformed--Thread undersize O/D of turned pipe is less, pressurevariation in the thread rollersLeakage in the threaded joints Pressure gauge on thread rolling m/c, check for threads using GO &NO-GO ring gauges for all threadsformed--Thread length more Wrong stopper used, loose stopper Dimensional issue rejection Setup approval for the m/c, issuingof roller for the jobIssuing specifiedstopper with the job cardThread length less Wrong stopper used Leakage in the threaded joint Setup approval for the m/c, issuingof roller for the job, leakagetesting for all joints finallyIssuing of specifiedstopper with the job cardCone cutting To get the required cone size The cone angle is more or less Setting of the m/c, wrong tool pieceusedLeakage and can lead to reduction inthe system performanceCNC m/c with programlocking, history card for tool life--Scratch/burr marks on the coneinternal surfaceSetting of the m/c, tool piece wornout, wrong tool piece usedLeakage and reduction in the systemperformance, metal contamination inhydraulic fluidCNC m/c with programlocking, history card for tool life--Drilling To drill holes at the drawing requirementsBurr formation at the drilled hole siteDrill bit worn out, wrong drill bit usedLeakage, seals can be cut100% flushing, reaming done to remove the burrHigh flushing coolant with step drillDrilled hole is at a different position than as per the drawing requirementsWrong fixture used, drilling without fixtureFitment issues at the customer end100% check on Part number on the drilling fixtures, poka yoke in fixtures for correct positioning--Reaming(de-burring)Removal of the burrs due to drillingBurr is not fully removedSmaller diameter of reaming tool usedCan lead to contamination, cutting of seals, etc.Issuing specified reaming tool--Burr and chips present on the pipe insideWorn out reaming tool is used, blind hole drilling leads to chips, burrs sticking to inner walls Can lead to contamination, cutting of seals, etc.History card of the reaming tool, one piece cut in each batch to check for burrs and chipsSetup fixture for reamingBending Set up the pipe on the mandrel Mandrel for bending is not placed SOP is not followed Profile of pipe produced is not as specified, pipemay have dents, etc. due to unaccounted forcesSOP is written, final inspection with fixture --Pipe positioned/located incompletely Improper insertion of mandrel in the pipe Profile of pipe produced is improper, defectslike dents, collapse, etc.100%inspection with bending fixture after bending, collet with stopperFixture with poka yokes for proper positioning of the pipeExcessive bending Pulley is worn out, wrong selection ofprogramme, unskilled operatorFitment problems at customer end, collapsing ofpipeHistory card for the pulleys used, locking ofthe PLC machines--Incomplete bending Wrong selection of programme, unskilled operatorFitment problems due to incomplete profile at customer endLocking of the PLC machines --Wrinkle/Collapse Clearance between pipe ID and mandrel isexcessiveRejection at the customer end or at the leakagetesting pointOperator visual inspection Issuing of correct size of mandrel with the job card, check the sizewith an operatorCrack Mandrel is not positioned correctly (position less than centre line of pulley)In-house rejection, leakage and rejection at customer endLeakage testing Sufficient precautions in placeStub welding Weldingof the stub as shown in the drawing requirementsWeld defects like pinhole, spatter, and blowholeDefects introducedby welders carelessnessFailureof the welded joint Operator visualinspection Automatizationof the weldingprocessThe positionof weldingis not as per the drawingFixtureis not used/correctly, correct fixtureis not usedFitmentissues at the customerendPart numberon the weldingfixturesPoka yokes in the fixturefor correct positioning Leakage testing The welded assembly shouldbe free of any leakage from poor weld at the timeof testingLeakage in whole assembly The fixturefor weldingis not proper, operator mistake, weldingwithoutfixturesLoss of primaryfunctionat the customerendTestingin m/c accompaniedby visual inspectionLeakage in part of the assemblyThe fixturefor weldingis not proper, operator mistake, weldingwithoutfixturesLoss of primaryfunctionat the customerendTestingin m/c accompaniedby visual inspectionLeakage in the weldingWeldingparametersare not maintained,operator incompetencyLoss of primaryfunctionat the customerendOperator visualinspection and m/c alarmPackaging and dispatchPackage the plated pipes and dispatch them for further processingLess or excess quantity of parts suppliedQuantity not verified with the bill for the parts requiredCustomer line may stop due to less quantity or cost loss on more quantity suppliedWeight the boxfor same type of parts like bolts, operator trainingWrong parts dispatched to customerWrong identification of the partsProduction line is held up with losses to the customerVerifying of the part number during dispatch--5 Technical aspects from JCB: Data security: The Lotus email software on the company PCs does not let employees to send the emails to any mail other than the certified dealers or between themselves. The USB port in the company laptop and desktops also does not allow the mounting of the pen drives or external hard drives. This insures the safety of the company data. However, it also causes some trouble to the employees when they are working from home or are on some company visit to an out of station supplier or place. Standard operating procedure: The SOPs helped even a newcomer to understand the proper procedure to follow. This helps to insure a proper standardised working method by workers. These were at each of the station on a board available to the workers. On- line testing: The oils and coolants from the finished machines are sent to the lab for analysis at regular intervals, even once in two hours. This insures that any contamination in a batch of oil received or in a machine is found out if it had escaped previously or had been contaminated in the meanwhile. Safety aspects: The JCB entrance reception does not allow anyone not wearing shoes to enter the premises for safety purposes. The first day we were unable to visit the factory lines because we were not wearing the standard safety shoes. Also everyone on the line is provided with goggles to prevent accidental injury to the eyes. Packaging standards: The packaging in JCB for different parts is very strictly followed. Workers do not open the caps of pipes just before the lunch break. Any contamination while transportation is minimised with proper packaging. The protocols are very strict since even a little atmospheric contamination can lead to failure of the machine.Time management by employees:Junior/senior engineerTechnical work Analytical workComputer work People managementDiscussion and meetings OtherManagerTechnical work Computer workPeople management Discussion and meetingsOtherBrief note on IT application: Data security Database management system Software3 problems worth solving at IIT Delhi: Synchronisation of the hydraulic pistons in the boom-dipper section Failure of the exposed hoses due to various factors Presence of gap in the ram pistonsThank you !!!