General Machine Shop Rules and ... - Auburn University



1905000-30480000BASIC MACHINE TRAINING GUIDETable of Contents TOC \o "1-3" \h \z \u General Machine Shop Rules and Training Courses PAGEREF _Toc398716425 \h 2Safety PAGEREF _Toc398716426 \h 5Machine and Equipment Care PAGEREF _Toc398716427 \h 6Precision Measurement Equipment PAGEREF _Toc398716428 \h 7Milling PAGEREF _Toc398716429 \h 8I.Machine Specific Setup PAGEREF _Toc398716430 \h 8II.Machining Operations PAGEREF _Toc398716431 \h 10III.Machining Considerations PAGEREF _Toc398716432 \h 10IV.Post machining PAGEREF _Toc398716433 \h 13Lathe PAGEREF _Toc398716434 \h 14I.Machine Specific Setup PAGEREF _Toc398716435 \h 14II.Machining Operations PAGEREF _Toc398716436 \h 15III.Machining Considerations PAGEREF _Toc398716437 \h 15IV.Post Machining PAGEREF _Toc398716438 \h 16Saws PAGEREF _Toc398716439 \h 17I.Machine Specific Setup PAGEREF _Toc398716440 \h 17II.Machining Troubleshooting PAGEREF _Toc398716441 \h 18Hot Shop PAGEREF _Toc398716442 \h 20General Machine Shop Rules and Training CoursesGeneral Machine Shop RulesFollow all safety guidelines (see Safety section below)If leaving part in machine, leave name, cell number, and time of returnTime of return may not exceed 2 hours without Advanced Machinist’s permissionPart may be removed at Advanced Machinist’s discretionMust leave shop cleaner than you found itAbsolutely no chips left behind (floor or machine)Chip residue wiped off of machines with Simple GreenCoolant wiped up from floor and machine, if usedTools cleaned and put in proper placeNo machine shop tools leave machine shopIncludes drill bits, taps/dies, and measuring devicesMetal stockStore only that which is actually useful within 1 year’s timeLabel stock with proper gradeKeep stock organizedFixturesStore on fixtures shelf – sorted by teamIf fixtures are useless or outdated, dispose Shop environmentKeyed interior doors are egress only – includes visitors and toursSafety glasses must be worn by everyone if work is being performed Stay inside yellow lines without proper PPE (safety glasses must still be worn)Keep showers/eye wash stations and fire extinguishers clearKeep aisles clear – must be able to egress shop easilyCategories of machinistsNewbie: Must have Advanced Machinist in machine shop at all timesBasic: Has successfully completed Newbie training – must have Advanced Machinist in machine shopAdvanced: Senior machinist – has highest level of authority in machine shop and must be present for any machining to take place. Will instruct on good safety practices and proper machining techniqueSetup CheckA setup check (see Safety section below) must be performed before any machine is operatedAuthorization for useNewbie: Must have Advanced Machinist check offBasic Machinist: Must have Advanced Machinist check offAdvanced Machinist: Can self-checkApproved Machinist NotebookIncludes training docsTraining CoursesBasic Machine training Attend class lectures and pass written examTeam captain nominates for continued trainingPaired with Advanced Machinist who will give machine demonstrations, general instruction, and observe student use on lathe, mill, and sawAdvanced Machinist will sign off on newbie after competency with machine and mill and lathe part checked for proper tolerancesWelding trainingReceive training from an Advanced WelderMust demonstrate proper welding technique by presenting 10 samples of various types of welds to Advanced WelderAdvanced Welder signs off on newbieSafetySetup Check – to be administered by Advanced MachinistSafety glassesProper attire – long pants, covered toe shoes, sleeves above elbow, no jewelry, etc.Hair tied back in bun – if applicable, hats turned backwardsWork and tool mounted securelyEverything clear of tool through range of cutImproper PPE or people not training must stay behind yellow linesCorrect speed calculated and acceptable depth of cut (see Newbie guide)Machining plan – Describe steps on how you plan to make your partPotential HazardsCutsSharp chipsChips falling into shoesMachine or tool breakageBurrs on work pieceProjectilesFlying chips/misuse of air nozzleFlying chuck wrench – keep hand on tool at all times until removedTool breakagePoorly clamped partEntrainment into machineImproper clothingLong sleevesGlovesNo dangly things, including jewelryHair not tied back in bun - long pony tail not acceptableBystanders not following proper safety precautionsLack of aidMust have buddy in machine shopIf no buddy, no machiningPoisoningInfected cuts from bacteria in stagnant water due to lack of Cool MistInhaling fumes from tap magicFireImproper cutting operation which creates sparksHot material placed on flammable surface (i.e. paper)Improper cutting of magnesiumUse big yellow fire extinguisher if fire eruptsCrushingImproper lifting of heavy objects – get assistance from othersPlan ahead and check foot path for obstructionsFallsSlippery floors due to coolantSlippery floors due to abundance of chipsTripping over objects – plan steps in advanceMachine and Equipment CareMeasuring Equipment (Calipers, Dial Indicators, Micrometers, etc)General CareHigh precision instruments must be handled carefullyNo sudden shocks – no dropping, beating, etcAvoid exposure to liquids (especially digital calipers), heat, dirt, etc.Improper use can cause them to lose their tolerances and make them uselessShop usageEquipment designated for machine shop must not leave the roomAlways store in designated locationMachine Cleaning ProcedureApplies to all machinesTo be performed upon completion of workAll chips removed from machine and floorChip residue wiped off of all surfaces on machine with Simple GreenDo not use Simple Green on greased surfaces – just wipe off with clean ragIf coolant used, wiped up completely from machine and floorAll tools cleaned and put back in designated locationMilling MachinesUse automatic oilers to lube ways on a weekly basis – Adv Machinists performCup oilers will be oiled by Support EngineerUse chip guardsDo not over tighten drawbarDo not leave wrench on drawbar – everDo not adjust speed unless machine is turned onMake sure spindle brake is not stuck in the engaged positionDo not allow tool to cut viseLathesOil LevelsAlways check sight glasses before useLow oil will cause damage to machineFill up if low using Medium Way Oil found in prep room cabinetUse chip guardsDo not leave chuck wrench on chuck – everAlways make sure tool and holder are clear of chuck before operationThoroughly clean insert holders when changing insertsCan cause all sorts of issues (poor surface finish, tool breakage, etc)Use anti-seize on threads to prevent stickingDo not over tighten insert screwsSawsClear chips after every use – can cause rustMake sure guides are adjusted properly – height and blade separationOccasionally check rubber on large pulleys for chips to removeIf changing gears, always do manually and make sure gear is engaged before operationPrecision Measurement EquipmentCalipersUsed for general purpose measurementBest for quick measurement of small partsMeasures: inside diameter, outside diameter, thickness, depthCan calibrate using gauge blockDial IndicatorsSome common usagesDial in part on latheTram mill and visePosition part relative to headMeasures: linear distanceMicrometersExcellent for measuring diameters and large openingsGenerally more accurate than calipersSome have greater range of measure than calipersUse gauge block to calibrateMeasures (our set): outside diameter, thicknessGauge BlocksUsed for measuring z-axisCan calibrate calipers and micrometersUse dab of oil on surfaces to increase precisionUsed to get accurate distancesTransfer GaugesUsed to measure places other equipment can’t get toDoes not read out a measurement, must use caliper/micrometer to obtain measurementVernier Dials on MachinesLathes and mills both have dial gauges in all directionsUse them when other instruments aren’t availableMillingMachine Specific SetupCoordinate systemPerfect 90° and flat surface cutsHead is trammed perpendicular to tableThoroughly clean table’s surface w/ lubricantMount dial indicator on spindleRotate spindle to make head perpendicular to table in X and Y directionsVise is trammed perpendicular to tableThoroughly clean mating surfaces w/ lubricantMount dial indicator on spindleRun indicator on back face of vise to square up to table Tool selectionEnsure it is sharp by looking at the tip of each toothSize tool to match cutting operationDetermine features needed for cutCalculate spindle speedLook up cutting speed for milling in Machinery’s HandbookRPM = 4 x cutting speed (sfm) / diameter of tool (inch)Speed changeCan cause damage to machine if done when machine is offPerform slowlyEnsure low/high lever is in proper position for RPM desiredPart clamping on tableUse clamps to keep part from shiftingClean table and part well so they seat wellPart clamping in viseMust be tight to keep part from shiftingUse parallels to make part level and adjust heightClean vise and part so they seat well Lightly clamp part, use mallet to firmly seat, then fully tightenPlan ahead and do not allow the tool to cut the viseLocate X and Y axesMethod 1Load edge finder into machine with colletSet speed to 1000 – 1400 RPMsSet edge finder height and slowly move X axis until finder “kicks” out. Subtract half the width of finder and zero axis.Repeat for Y axisMethod 2Take cut with one axis (lock other axis in place)Measure part (do not remove part from vise)Subtract that figure from desired measurementUse DRO to obtain desired measurementLocate Z axisUsing feeler gaugeClamp part and insert tool onto machineWith machine off, get part close to bottom of toolSlide gauge between part and tool while raising part until gauge slides with minimal friction (Caution: raising too much may chip tool)Move part up gauge thicknessGauge blockClamp part and insert tool onto machineWith machine off, get part close to bottom of toolMove gauge block between part and tool while raising part until tool touches gauge blockMove part up length of gauge blockDepth of Cut (radial and axial)Note: Numbers to be used as a rule of thumbFace milling (axial cutting)Steel: 0.01” (half aluminum)Width of Cut = 75% width of tool – reduce DOC if moreAluminum: 0.02” (2x steel)Width of Cut = 75% width of tool – reduce DOC if more Shoulder/contour milling (radial cutting only)Steel: 0.01” (half aluminum)Width of Cut = 75% width of tool – reduce DOC if moreAluminum: 0.02” (2x steel)Width of Cut = 75% width of tool – reduce DOC if more CoolantSteel: When using HSS bits, may want to use to help with tool lifeCutting aluminum: not neededNot needed with carbide indexable toolsNot an excuse to go fasterFeedAlways feed part into bit slowly to get a feel for toolObserve chips, if chips too hot to touch, slow feed downNo way to accurately set feed rate, so calculation on manual mill means littleMachining OperationsFace millingTaking large portions of metal off top of part to get to certain depthFastest way is to use the “Bearclaw” indexable cutterSpeed: 900 RPM, material: aluminum only, DOC: 0.04” maxNever engage ~50% of tool due to improper insert loading. 70% ideal, 25% okSlot millingUses 100% width of toolReduce depth of cut by 50%Is the hardest operation a tool will experienceShoulder/contour millingCutting on outsides of part which engages less of toolCan take larger depth of cut but width of cut is shallowPocket millingCutting the inside of the partNot typically a manual milling operationFirst pass is similar to slot millingIf extra passes are required, depth of cut may be slightly increasedTake it slow in corners since it will engage more of the toolDrillingUse drill press or drill chuck with integrated taper for millFind sharp bitDetermine hole size and find 2-3 bits to step up to that size(if over ?”) – larger drill bits don’t cut in the center wellFor deep holes, peck drill – pick up quill to clear chips every ?” or soIf gets hot, find sharper drill or use some coolantNote: Drilling does not provide very accurate or round holes – see reamingReamingFollow procedure for drillingReduce final size of hole by ~1/32” for small holes (less than ?”)Install reamer into proper colletReduce spindle speed by at least halfMachining ConsiderationsSurface finishUse sharp toolTake smaller depth of cut (ie, finishing cut)Take larger depth of cut – too small and cutter radius may be too large to cutIncrease or decrease speed and feed 10% to see if finish improvesUse climb millingTool lifeUse proper speeds and feedsPossible use of coolantProper depth of cut and width of cutAccuracyDo not get in a hurry, take your timeMeasure twice (with precision tools), cut onceNoise reductionCheck speed – adjust ±150 RPMsIncrease feed rate – tool is possibly rubbingUse sharp bitPart getting too hot Identified by physically feeling chips – catch some chips in hand with cautionchip discoloration – only observable with steel – chips turn bluecontinuous smokeAdjust speedUse slower feed rateTake less depth of cutUse sharper toolNote: Excessive heat reduces strength of tool and damages itSquare stockClamp round rod in with part in viseKeep rotating part till each surface is machined 8191506540500Small diameter hole (less than ?”)Use DRO and center drill to locate holeUse 2-3 drill bits to increase size to desired diameterFor highest accuracy, undersize hole 1/32” and use reamer for the final cutLarge diameter hole (greater than ?”)Follow above procedure and continue increasing drill bit sizesWhen size exceed drill bit available, use boring headNote: Don’t be afraid to ask for help to set up properlyCut part to specified heightMeasure height of part and locate end of tool to top of partCalculate depth of cut Use vernier scale on Z axis to raise table incrementally to desired heightCut part to specified length or widthClamp part such that cut can be performed (ie, hang off end of vise)Use edge finder and DRO to locate both ends (be sure to account for tool diameter if it applies)Make incremental cuts to desired length or widthRidges in surface of partHead not trammedTool has teeth missingInsert installation - BearclawFind correct tool to undo screws – do not strip!Remove old insert and install new onePut anti-seize on threads of screws and do not over tighten Post machiningDeburringImproves accuracy if performing more machining operationsPrevents cuts on handsRemoves crack inception sitesMakes part look finishedTappingDetermining hole sizeLocate tap chart and find thread desiredSelect drill size according to chartNote percent of thread changes depending on drill sizeKeep part in machine and accurately locate holes – do NOT turn on machine!Loosely put tap in chuck and start by hand a few threads to line up tapEnsures tap is perpendicular to partUse cutting fluid liberallyClean upLeave machine and shop cleaner than you found itPut all tools back in their proper placeProperly label extra stock and put in designated place on shelfRemove all chips with brush – use air nozzle only for hard to reach placesPrevents lost tools and promotes safe working environmentClean precise tools make clean precise partsLatheMachine Specific SetupCoordinate systemTool selectionDetermine type of cut (facing, inner/outer diameter, cut off, etc)Select proper tool for cutBoring – use boring toolFacing, turning – WNMG/CNMG insert toolSet tool heightFace part and reduce size of nub to nothing - tool is setPut center in tailstock and set tool heightUse height adjustment tool (soon to be built)Speed selectionLook up cutting speed for turning in Machinery’s HandbookRPM = 4 x cutting speed (sfm) / diameter of tool (inch)Set levers to closest calculated numberClamp part3 JawUse chuck tool to clamp down part – don’t get “super” tightRemove chuck tool before starting machine – tool never leaves handPart will be between 0- ~0.005” from centerIf part not perfectly centered, on first pass of tool, working area of part will be perfectly centered4 JawLine up part using dial indicator w/ magnetic baseRotate chuck and use chuck tool to clamp down partRemove chuck tool before starting machine – tool never leaves handDepth of CutNote: Numbers to be used as a rule of thumbSteel: 0.015” (half aluminum)Aluminum: 0.03” (2x steel)Maintenance issuesBe sure to check oil level before useFill up if low using Medium Way Oil found in prep room cabinetMeasuringDRO defaults to measure on the diameter (can be set to read on the radius)Vernier dials read on the diameterCoolantNot advised to use coolant with carbide inserts – creates micro cracks in insertDefinitely used on drilling and HSS toolsChanging insertsFind correct tool to undo screws – do not strip!Use air to blow out any chips in socketRemove old insert and install new onePut anti-seize on threads of screws and do not over tighten Machining OperationsFacingMachine end of partMust use some form of right hand tool cutterSet depth and use X axis feed to face offTurning - Outer diameterMachine outside surface of partCan use any form of tool holderDrillingPuts holes through partInstall drill chuck in tailstock – use coolantPeck drill (move drill bit in and out of hole every ~?” to clear chips)Gradually increase size of drill bit (if over ?”) until desired size is reachedUse boring tool if hole needs to be bigger than available drill bit sizeBoring - Inner diameter Makes part that requires an inner diameterUse boring tool that corresponds to the size hole in the partOnly stick bar out as far as absolutely necessary – more overhang = less rigidMax overhang – HSS: 4x diameter of bar, Carbide: 6x diameter of barParting - Cut offCut off part from stock clamped in chuckMust reduce speed by 50%May need to take a multiple cuts as tool has tendency to wanderAdjust so insert overhang is minimizedMachining ConsiderationsSurface finishAdjust speed ±150 RPMsAdjust tool to centerline of partMake sure tool is sharpUse proper tool for the job (see Tool selection above)Take larger depth of cut – too small and insert radius may be too large to cutLeave a few thousandths and sand part down for best finishAccuracyUse DRO with caution. Always stop and measure oftenLeave plenty of time to stop and measureNoise reductionCheck speed – adjust ±150 RPMsIncrease feed rate – tool is possibly rubbingUse sharp bitPart getting too hotUse slower feed rateTool is dullToo large a depth of cutNote: Excessive heat reduces strength of tool and damages itChip clearingDo NOT remove chips while machine is turning. Stop machine first then removeDo NOT use gloves to clear chips while machine is running. This is worse than above. Gloves ok after machine is stoppedPost MachiningDeburringImproves accuracy if performing more machining operationsPrevents cuts on handsRemoves crack inception sitesMakes part look finishedTappingKeep part in machine and accurately locate holes – do NOT turn on machine!Put chuck in tailstockLoosely put tap in chuck and rotate head by hand a few threads to line up tapEnsures tap is perpendicular to partUse cutting fluid liberallyClean upLeave machine and shop cleaner than you found itPut all tools back in their proper placeProperly label extra stock and put in designated place on shelfRemove all chips with brush – use air nozzle only for hard to reach placesPrevents lost tools and promotes safe working environmentClean precise tools make clean precise partsSawsMachine Specific SetupBladeThree teeth contact part at all times – more the betterAluminum uses larger pitch to aid in chip clearingSteel uses smaller pitch to engage more teeth in the cutValleys in blade remove chipsAdjust blade guide height to fit material thicknessBlade typesCarbon steel – Good for soft metals, cheaperBimetal – HSS cutting teeth bonded to carbon steel backing. Good for harder steels and improves blade lifeCarbide blade – Ideal for hardened steel, expensiveVariable pitch blade reduces vibration and increases blade life and finishHorizontal saw: 5-8 TPI (teeth per inch) good for ?” or larger material146939017335500Vertical saw: 10-14 TPI good for ?” and belowSpeedVertical SawSee chart on side of machineDetermine type of material used and thicknessAdjust dial to proper speed indicatedHorizontal SawSpeed adjusted by belts. Typically good for general purpose.Part holding – Vertical sawDo not use hands with small partsUse V-type part holder – should be located close to sawUse wood to push throughUse small vise to hold round material – do NOT allow round stock to rotate, it will destroy bladeFeedVertical SawSee chart on machine and use specified feedFeeds listed in rabbit, donkey, and elephant. For rabbit, do NOT push hardUse part holder to prevent injuryHorizontal SawFeed automaticFor thin wall tubing – slow feed manually or don’t useCan adjust weight to apply more force on cutMachining TroubleshootingHot materialFeeding too fastDull bladeImproper speedPoor surface finishFeeding too fastDull bladeImproper speedBlade guides adjusted improperlyPoor blade cuttingDull bladeSpeed too highBlade guides adjusted improperlyTeeth pointed wrong direction/blade installed backwardsSaw not cutting in straight lineBlade guide height too highBlade guides not set properly – reduce separationToo high feed rateNot holding part rigid enoughHigh force required to cut – see Poor blade cuttingLoud noisesFeeding too fastDull bladeImproper speedTeeth strippingFeed pressure too highTooth stuck in cutPart spinningSpeed too lowChip test – see following chart Hot ShopSafetyFollow machine shop safety rulesEveryone must have safety glasses if work is occurringNo flammable material allowed in areaBefore any hot operation (sparks, etc) check for accidental placement of flammable material near areaBe extra cautious of sharp objects (burs on metal, sharp edges, etc). Always place materials in place someone cannot accidentally walk past and cut themselvesMake sure all gas bottles are securedGrinders Bench grindersEnsure guards are properly adjustedSteady part when grinding – if it slips, can cut skinUse pliers/vise grips to hold partSide grinder/dremel/air grinderDetermine path of sparks before starting and make sure area is clearEnsure part is clamped securelyChop sawUse ear protection in addition to eye protectionAnnounce to shop beginning of operation so everyone is prepared for the loud soundDo not put excessive pressure on handle when cutting – can prematurely wear bladeWelderDo not touch – must take and pass welding training classDo not look at pretty blue light when someone is welding or if you are forced to hold something in place ................
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