ASTM_B_320_-_60_2013.pdf

Designation:B32060(Reapproved 2013)Endorsed by AmericanElectroplaters SocietyEndorsed by NationalAssociation of Metal FinishersStandard Practice forPreparation of Iron Castings for Electroplating1This standard is issued under the fixed designation B320;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice is intended to assist electroplaters inestablishing and maintaining a satisfactory pre-electroplatingcycle for malleable iron,gray iron,nodular iron,and white ironcastings.It is also intended to indicate certain foundry practiceswhich will facilitate subsequent finishing.Most of the practicesthat follow have been based on experience with malleable andgray iron.However,since they are related to the other forms,the same practices will probably apply.Nodular iron is alsoknown as spheroidal or ductile iron,which is defined as castiron with the graphite substantially in spherical shape andsubstantially free of flake graphite.1.2 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.Specific precau-tionary statements are given in 2.1.2.Reagents2.1 Purity of ReagentsAll acids and chemicals used in thispractice are technical grade.Diluted acid solutions are basedupon the following assay materials:Hydrochloric acid(HCl):31 mass%,density 1.16g/mLHydrofluoric acid(HF):47 mass%,density 1.186g/mLSulfuric acid(H2SO4):93 mass%,density 1.83g/mL(WarningUse hydrofluoric acid with extreme care.)(Warning Sulfuric acid should be slowly added to theapproximate amount of water required with rapid mixing,andthen after cooling,diluted to exact volume.)2.2 Purity of WaterOrdinary industrial or potable watermay be used for preparing solutions and rinsing.3.Foundry Practices3.1 The seacoal content of the molding and facing sandsshould be maintained at the maximum practicable limits tominimize the occlusion of sand in the surfaces of the castings.3.2 Upon removal from the molds,castings should besubjected to an abrading action(such as tumbling,grit blasting,or shot blasting)to remove as much as practicable of theoccluded molding sand.Residual sand and scale may beremoved,if necessary,by treatment in various proprietarydescaling baths.These are usually based on fused caustic soda,some of which use chemical oxidizing or reducing agents andothers employ electrochemical action as well.This is particu-larly important in the case of castings that will be annealed,toprevent the burning on of sand during this operation.Castingsthat will be warped or damaged by a blasting operation may bepickled in a solution containing 200 to 250 mL/L of sulfuricacid to remove occluded molding sand.See Warning state-ment in 2.1.3.3 Annealed castings should be given an additional abrad-ing as described in 3.2 to remove any scale that may have beenformed,as well as graphitic carbon that may be present at thesurface.4.Nature of Cleaning4.1 The preparation of ferrous castings for electroplatinginvolves the following basic steps in the order named:4.1.1 The removal of oils,greases,residual polishing andbuffing compounds(if any),and shop dirt by cleaning,4.1.2 The removal of oxide films and scales and the loos-ening of surface carbon by pickling or by salt bath treatment(see 3.2),4.1.3 The removal of smut caused by 4.1.2,and4.1.4 Activation for electroplating.4.2 Where excessive amounts of cutting oils used in ma-chining operations are present,it may be necessary to precleanthe parts before they reach the electroplating room.This mayrequire the use of organic solvents,vapor degreasers,washingmachines of the power-spray type,emulsion cleaners,orsimple alkaline soak tanks.As short a time as possible shouldelapse between this precleaning and the preplating cleaningcycle so as to prevent rusting of the parts.Where control of the1This practice is under the jurisdiction of ASTM Committee B08 on Metallicand Inorganic Coatings and is the direct responsibility of Subcommittee B08.02 onPre Treatment.Current edition approved Dec.1,2013.Published December 2013.Originallyapproved in 1960.Last previous edition approved in 2008 as B310 60(2008).DOI:10.1520/B0320-60R13.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 interval is not possible,parts should be left with a slightlyalkaline or very thin organic film.5.Cleaning Solutions and Equipment5.1 The various solutions used for the treatment of mal-leable and gray iron castings should be maintained by chemicalanalysis so far as is practicable,such as determining the freeacid and iron concent