Forgingterms
Duringdieforging,theexcessmetalinthecavityofthefinalforgingdieflowsintotheflashgroovetoformacircleofmetalaroundtheforging.Ithasthefunctionofensuringthatthemetalfillsthemoldcavity.Itmustbepracticalafterdieforging.
Inthemoldingprocess,itoverflowsintothegapbetweenthemoldclampinglineortheejectorpinandremainsontheremainingmaterialedgeoftheplasticpart.Itcanberemovedbypolishing,grindingandothermethods.Thisisduetothelowaccuracyofthecontactsurfacebetweenthemalemoldandthefemalemold,theexcessiveamountofmaterial,andtheleakageoftheremainingmaterialattheweakseal.
Fly,cutting,removing.Flashingreferstocuttingouttheedge,whichisabindingterm.
Reasons
FlashgenerationButhowtoreduceflashandimprovethequalityofplasticpartsisanimportantresearchtopicinthefieldsofplasticmoldingprocessingandprecisioninjectionmolding.Theoccurrenceofflashmaybecausedbythefollowingreasons:
1.Ifthemaximumclampingforceofthemachineisnotenough,amachinewithsufficientclampingforceshouldbeselected.Thehingesoftheclampingmachinearewornorthesealingelementsoftheclampingcylinderarewornandtheoildripsorbackflows,whichcausestheclampingforcetodrop.Theheatingsystemisoutofcontrolandtheactualtemperatureistoohigh.Checkwhetherthereisanyproblemwiththethermocouple,heatingcoil,etc.
(1)Unbalancedmoldcavitydistributionorinsufficientparallelismcausesunbalancedforcesandlocalflashesandlocaldissatisfaction.Therunnershouldbeplacedinthequalityasfaraspossiblewithoutaffectingtheintegrityofthepart.Centerofsymmetry.
(2)Unbalancedforcesonmovablecomponentsandslidingcoresinthemoldwillcauseflash.
(3)Whenthemoldexhaustispoor,thecompressedairwillexpandthepartingsurfaceofthemoldandflash,soagoodexhaustsystemshouldbesetup,orthepartingsurfaceshouldbediggedforexhaust.ditch.
2.Ifthefluidityoftheplasticistoolarge,oraddtoomuchlubricant,thepressure,speed,temperature,etc.shouldbeappropriatelyreduced,andtheamountoflubricantusedshouldbereduced.Ifnecessary,plasticswithlowfluidityshouldbeused.
3.Processingandadjustmentaspects:
(1)Ifthetemperature,pressure,andspeedaresettoohigh,segmentedinjectionshouldbeused.Injectiontime,pressureholdingtime,andtoomuchfeedwillcauseflash.
(2)Duringadjustment,thehingeofthemoldclampingmachineisnotstraightened,orthemoldadjustmentnutoftenmoveswhenopeningorclampingthemold,resultingininsufficientclampingforceandflashing.
(3)Theparallelismbetweentheadjustingheadandthediodeisnotenoughortheadjustedsystempressureistoohigh.
4.Reasonsforrecurringflashinganddissatisfactionwithparts:
(1)Whentheparticlesizeofplasticrawmaterialsisuneven,theamountoffeedwillbeuncertain.
(2)Theabrasionofthescrewhead,rubberringandrubbergasketistoolarge,sothatthemeltmayslipbetweenthescrewandthebarrelandreturntocauseflashordissatisfaction.
(3)Thecoolingsystemattheinletfails,causingtheadjustmentofthefeed.
(4)Thesetinjectionvolumeofthebarrelisinsufficient,thatis,ifthecushionistoosmall,itwillcauseflashingordissatisfactionofthepart.
Solution
Thefirstsolutiontoflashisthecauseofflash:
1.Theslidingsurfaceofthemoldpartingsurface(PL)doesnotmatch;
2,theinjectionpressureistoohigh;
3,theoffsetoftheinjectionmachine;
4,theclampingforceisinsufficient.
Problemsrelatedtothemold:
1.ThepartingsurfacePLofthemold,theslidingmatingsurface,thereleasepin,thespacer,etc.Thegapbetweenthevariousgroovesthatconstitutethemoldwillbecomeflashifthematerialislost.Theflashisawedge-shapedblock.Thereisatendencytograduallyincrease;
2.Theprincipleofeliminatingtheflashoftheproductisgenerallytorepairthemold.Iftheflashoccurstemporarilyduetopoormoldingconditions,thebarreltemperatureshouldbelowered.Setparametersinthedirectionofloweringthemoldtemperatureandloweringtheinjectionspeedtoreducethefluidityofthematerial.However,itshouldbenotedthatthiswillcauseresidualinternalstressintheproduct.
Solution:
1.Immediately:reducetheinjectionpressureandreducethetemperatureoftheheatingbarrel.Reducetheinjectionspeed;
2,short-term:grindingtheflashingsurfaceofthemold;
3,long-term:themolduseshardsteelmaterials.
Duetothedifferenceofmaterials:1.Becausethematerialwithgoodfluidityispronetoflash,themoldpartingsurfaceshouldbemadetightly;2.Theviscosityofcrystallinematerialisverylowwhenitismelted.Inparticular,thetightnessofthemoldpartingsurfaceisrequired.
References:1.Itshouldbenotedthatexcessivepressureonthemoldwillalsoproduceflashing,andforeignobjectsbetweenthepartingsurfaceswilldamagethemoldandproduceflashing;2.MoldThematerialusuallyusesS50Candothermaterials(JapaneseJJSstandardisequivalenttodomestic50#steel)andpre-hardenedspecialsteelofHRC30,soitisdifficulttoproduceflashonthepartingsurface.