SIST EN 13887:2003
(Main)Structural Adhesives - Guidelines for surface preparation of metals and plastics prior to adhesive bonding
Structural Adhesives - Guidelines for surface preparation of metals and plastics prior to adhesive bonding
This European Standard specifies the usual procedures for the preparation of component surfaces prior to bonding for either laboratory evaluation or the process of construction.
This European Standard is applicable to metal and plastic surfaces that are commonly encountered.
These comprise the following metal and plastic families - the latter including filled versions and suitable paints :
METALS: aluminium, chromium, copper, magnesium, nickel, steel (mild), steel (stainless), tin, titanium, zinc.
PAINTS: cataphoretic, polyalkyd, polyester, polyepoxide, polyurethane.
PLASTICS:
thermoplastic: Acrylonitrile/butadiene/styrene plastic (ABS plastic), Polyacetal plastic, Polyacrylic plastic, Polyamide plastic (PA plastic), Poly( butylene terephthalate) (PBT), Polycarbonate plastic (PC plastic), Polyester plastic, Polyetheretherketone (PEEK), Polyethersulfone (PES), Polyethylene plastic (PE plastic), Polyimide, Poly(methyl methacrylate) plastic (PMMA plastic), Poly(phenylene oxide) (PPO), Polypropylene plastic, Polystyrene plastic (PS plastic), Polytetrafluoroethylene (PTFE), Poly(vinyl chloride) plastic (PVC plastic).
thermoset: Allylphthalate plastic, Aminoplastic, Cellulose esters, Epoxy plastic, Polyester plastic, Phenolic plastic, Polyurethane (PUR).
Strukturklebstoffe - Leitlinien für die Oberflächenvorbehandlung von Metallen und Kunststoffen vor dem Kleben
Diese Europäische Norm legt die üblicherweise zur Vorbehandlung von zu klebenden Komponenten-oberflächen durchgeführten Verfahren fest; diese gelten sowohl für die Beurteilung im Labor als auch für den Prozess der Herstellung der Verbindung.
Diese Europäische Norm gilt für allgemein übliche Metall- und Kunststoffoberflächen.
Dazu gehören folgende Metall- und Kunststoffgruppen, wobei die letztgenannten auch füllstoffhaltige Arten und geeignete Anstrichstoffe enthalten:
METALLE: Aluminium, Chrom, Kupfer, Magnesium, Nickel, Stahl (weich und unlegiert), Stahl (nicht rostend), Zinn, Titan, Zink.
ANSTRICHSTOFFE: kataphoretische, Polyalkyd, Polyester, Polyepoxid, Polyurethan.
KUNSTSTOFFE:
Thermoplaste: Acrylnitril-Butadien-Styrol-Kunststoff (ABS-Kunststoff), Polyacetal-Kunststoff, Polyacryl-Kunststoff, Polyamid-Kunststoff (PA-Kunststoff), Polybutylenterephthalat (PBT), Polycarbonat-Kunststoff (PC-Kunststoff), Polyester-Kunststoff, Polyetheretherketon (PEEK), Polyethersulfon (PES), Polyethylen-Kunststoff (PE-Kunststoff), Polyimid, Polymethylmethacrylat-Kunststoff (PMMA-Kunststoff), Polyphenylenoxid (PPO), Polypropylen-Kunststoff, Polystyrol-Kunststoff (PS-Kunststoff), Polytetraflourethylen (PTFE), Polyvinylchlorid-Kunststoff (PVC-Kunststoff).
Duroplaste: Allylphthalat-Kunststoff, Amino-Kunststoff, Celluloseester, Epoxid-Kunststoff, Polyester-Kunststoff, Phenolharzkunststoff, Polyurethan (PUR).
Adhésifs structuraux - Guide pour la préparation des surfaces des métaux et des plastiques avant le collage par adhésif
La présente Norme européenne spécifie les modes opératoires généralement suivis pour la préparation des surfaces de composants avant collage, soit pour l'évaluation en laboratoire, soit pour le procédé de fabrication.
Cette Norme européenne s'applique aux surfaces plastiques et métalliques usuelles, a savoir les familles de métaux et de plastiques suivantes (les surfaces plastiques incluant les plastiques chargés et les peintures appropriées) :
METAUX : aluminium, chrome, cuivre, magnésium, nickel, acier (doux), acier (inoxydable), étain, titane, zinc.
PEINTURES : traitées par cataphorese, poly-alkyde, polyester, polyépoxyde, polyuréthane.
PLASTIQUES :
Thermoplastiques : acrylonitrile/butadiene/styrene (ABS), polyacétal, polyacrylate, polyamide (PA), poly(butylene téréphthalate) (PBT), polycarbonate (PC), polyester, polyétheréthercétone (PEEK), polyéthersulfone (PES), polyéthylene (PE), polyimide, poly(méthacrylate de méthyle) (PMMA), poly(phénylene oxyde) (PPO), polypropylene, polystyrene (PS), polytétrafluoroéthylene (PTFE), poly(chlorure de vinyle) (PVC).
Thermodurcis : polyphthalate d'allyle, aminoplastes, esters cellulosiques, polyépoxydes, polyesters, phénoplastes, polyuréthanes (PUR).
Konstrukcijska lepila – Navodila za pripravo kovinskih in polimernih površin za lepljenje
General Information
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Konstrukcijska lepila – Navodila za pripravo kovinskih in polimernih površin za lepljenjeStrukturklebstoffe - Leitlinien für die Oberflächenvorbehandlung von Metallen und Kunststoffen vor dem KlebenAdhésifs structuraux - Guide pour la préparation des surfaces des métaux et des plastiques avant le collage par adhésifStructural Adhesives - Guidelines for surface preparation of metals and plastics prior to adhesive bonding83.180LepilaAdhesives25.220.10Priprava površineSurface preparationICS:Ta slovenski standard je istoveten z:EN 13887:2003SIST EN 13887:2003en01-december-2003SIST EN 13887:2003SLOVENSKI
STANDARD
SIST EN 13887:2003
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 13887August 2003ICS 25.220.20; 83.180English versionStructural Adhesives - Guidelines for surface preparation ofmetals and plastics prior to adhesive bondingAdhésifs structuraux - Guide pour la préparation dessurfaces des métaux et des plastiques avant le collage paradhésifStrukturklebstoffe - Leitlinien für dieOberflächenvorbehandlung von Metallen und Kunststoffenvor dem KlebenThis European Standard was approved by CEN on 10 July 2003.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Management Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and UnitedKingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2003 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 13887:2003 ESIST EN 13887:2003
EN 13887:2003 (E)2ContentspageForeword.3Introduction.41Scope.62Normative references.63Terms and definitions.64Safety and environment legislation.75Initial preparative techniques.75.1General.75.2Handling.85.3Cleaning.85.4Storing.86Surface modification.86.1Physical: Mechanical (scarification).86.2Physical: Non-mechanical.96.3Chemical.106.4Combined procedures.147Preparative procedures.157.1General.157.2Metals.157.3Plastics.278Evaluation of durability.29Bibliography.30SIST EN 13887:2003
EN 13887:2003 (E)3ForewordThis document (EN 13887:2003) has been prepared by Technical Committee CEN /TC 193, "Adhesives", thesecretariat of which is held by AENOR.This. European Standard shall be given the status of a national standard, either by publication of an identical text orby endorsement, at the latest by February 2004, and conflicting national standards shall be withdrawn at the latestby February 2004.This document has been prepared under a mandate given to CEN by the European Commission and the EuropeanFree Trade Association, and supports essential requirements of EU Directive(s).According to the CEN/CENELEC Internal Regulations, the national standards organizations of the followingcountries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal,Slovakia, Spain, Sweden, Switzerland and the United Kingdom.SIST EN 13887:2003
EN 13887:2003 (E)4IntroductionHistorically, surface preparation has required the use of solvents and reactive chemicals. However, it should benoted that the use of such materials is now generally deprecated and individual identified substances are becomingprogressively banned throughout the EU. For these reasons, traditional procedures using, for example, chromicacid are – with one exception - not provided in this standard. In addition, such chlorinated solvents, as may beallowed by the Montreal Protocol and National laws, should only be used in enclosed systems. Even so, the use ofthese solvents is not generally supported by this standard. See also EU Regulation (EC) No 2037/2000 [1].In order to achieve the optimum environmental durability from a bonded joint, the traditional preparative approachusually, though not necessarily, consists of three sequential steps:¾ the removal of contaminants;¾ physically induced modification of the surface;¾ chemical treatment.However, legislative pressure is driving development and with that the introduction of new methods. In these latter, themore hazardous oxidative treatments, and their associated disposal problems, are avoided. The correspondingintroduction of less aggressive oxidising techniques, or the use of coupling agents, often allows the separate steps ofthe foregoing sequence to be advantageously combined. These new processes are largely proprietary and, whereused, the coupling agents tend to be based upon silane chemistry. However, whatever the process, it is importantto realise that while the effectiveness of the new techniques (presented here) is well established, general utilitycannot be assumed. Consequently, it is necessary to demonstrate that any method selected is appropriate for theintended purpose and that the optimal conditions for the production process itself have been correctly established.Some materials will bond far better than others and some will not bond at all without special treatment. Thesuitability of a surface for bonding depends upon the degree of surface preparation, the joint’s design, its function(joining, sealing, etc.) and the environment in which it has to perform.Prior to bonding, some degree of surface preparation is required for most adhesives - but not all.
Material surfacesthat are particularly prone to weak or loose surface-layers, stress cracking or solvent attack usually require specialtreatment.Following appropriate preparation, most engineering metals, or their alloys, can be bonded satisfactorily. However,the optimisation of the durability of a metal-based joint usually requires the introduction of progressively more complexand specific treatments.The majority of both thermoset and thermoplastics materials can be prepared by commonly applicable techniques.Were it not for contamination and residual mould release agents, the thermoset plastics (e.g. polyepoxy andpolyester composites) would bond well without any preparation at all. By contrast, most thermoplastics requirecareful preparation because of their low surface energy. However, while the techniques required are generallyapplicable there will often be differences in the process detail.Some paints - especially the cataphoretic, water-based primers used by the vehicle industries, can provide anexcellent surface for bonding. Nevertheless, a check of the stability of the interface below the paint isrecommended. Sometimes the surface of the paint, even if fresh, can require treatment in order to raise its freeenergy and thus facilitate wetting.Certain adhesives possess the ability to dissolve light oils and some polymeric materials. Consequently, for joints thatare not "safety-critical" some surfaces do not require any preparation at all prior to bonding.The various methods provided for cleaning and modifying surfaces are drawn from current and developing practice.The techniques described can be used in a variety of combinations to create the basis of a practical, preparativeprocess that will provide enhanced environmental durability.SIST EN 13887:2003
EN 13887:2003 (E)5This standard does not provide a means of identifying the most appropriate method of preparation. This can onlybe determined, in particular instances, with regard to the manufacturing process and the eventual use of thebonded items. However, in any event, the method used, should
be both compatible with evolving Nationallegislation and EC regulations and represent the least hazardous means of achieving the performance required.A variety of process options are described for commonly encountered metals and plastics in clause 7.SIST EN 13887:2003
EN 13887:2003 (E)61 ScopeThis European Standard specifies the usual procedures for the preparation of component surfaces prior to bondingfor either laboratory evaluation or the process of construction.This European Standard is applicable to metal and plastic surfaces that are commonly encountered.These comprise the following metal and plastic families – the latter including filled versions and suitable paints :METALS: aluminium, chromium, copper, magnesium, nickel, steel (mild), steel (stainless), tin, titanium, zinc.PAINTS: cataphoretic, polyalkyd, polyester, polyepoxide, polyurethane.PLASTICS:thermoplastic: Acrylonitrile/butadiene/styrene plastic (ABS plastic), Polyacetal plastic, Polyacrylic plastic, Polyamideplastic (PA plastic), Poly( butylene terephthalate) (PBT), Polycarbonate plastic (PC plastic), Polyester plastic,Polyetheretherketone (PEEK), Polyethersulfone (PES), Polyethylene plastic (PE plastic), Polyimide, Poly(methylmethacrylate) plastic (PMMA plastic), Poly(phenylene oxide) (PPO), Polypropylene plastic, Polystyrene plastic (PSplastic), Polytetrafluoroethylene (PTFE), Poly(vinyl chloride) plastic (PVC plastic).thermoset: Allylphthalate plastic, Aminoplastic, Cellulose esters, Epoxy plastic, Polyester plastic, Phenolic plastic,Polyurethane (PUR).2 Normative referencesThis European Standard incorporates by dated or undated reference, provisions from other publications. Thesenormative references are cited at the appropriate places in the text, and the publications are listed hereafter. Fordated references, subsequent amendments to or revisions of any of these publications apply to this EuropeanStandard only when incorporated in it by amendment or revision. For undated references the latest edition of thepublication referred to applies (including amendments).EN 923:1998, Adhesives - Terms and definitions.EN 2243-5, Aerospace Series – Structural adhesives – Test methods - Part 5: Ageing testsEN ISO 472:2001, Plastics – Vocabulary (ISO 472:1999).3 Terms and definitionsFor the purposes of this European Standard, the terms and definitions given in EN 923:1998 and in ENISO 472:2001 and the following apply.3.1plastic (including paint)Material which contains as an essential ingredient a high polymer and which at some stage in its processing intofinished products can be shaped by flow.NOTE 1Elastomeric materials, which also are shaped by flow, are not considered as plastics.NOTE 2 In some countries, particularly in the United Kingdom, it is a permitted option to use the term "plastics" as thesingular form as well as the plural form.NOTE 3Adapted from EN ISO 472SIST EN 13887:2003
EN 13887:2003 (E)74 Safety and environment legislationThe users of this standard shall be familiar with normal laboratory practice and the principles of good industrialhygiene.This standard does not purport to address all safety problems, if any, associated with its use. It is the responsibilityof the user to establish safety and health practices and to ensure compliance with any European and nationalregulatory conditions.Some of the methods given below employ dangerous techniques, materials and proprietary chemicals. It isessential therefore that the suppliers' instructions are followed, health and safety data studied and appropriatesafety procedures established.Concentrated acids, alkalis and oxidising agents are highly corrosive chemicals. Splashes can cause severedamage to both skin and eyes and will damage normal clothing. Protective clothing (e.g. overalls, gloves andgoggles or visors) shall always be worn when using these chemicals.Similarly, appropriate precautions shall be taken when using solvents. At a minimum, eye protection and gloves (orappropriate barrier cream) shall be worn. Do not allow any cleaning materials to contact the skin. Abuse can lead todermatitis.Attention is drawn to the identification of solvents in accordance with EU Directive 89/655/EEC [2].Wherever possible use propan-2-ol as a solvent, preferably in a closed system. Otherwise, if there is no practicalalternative, a ketone can be used though it shall be employed in a closed system. Take care! All solvent-associated, handling processes shall take into account the flammability of alcohols and ketones - particularlyketones – and the fact that all such materials are narcotic in concentration. Ensure that appropriate precautions aretaken to eliminate all sources of solvent vapour and ignition – particularly electro-static sparking and to preventoperators from being exposed to solvent vapour during any part of the work cycle.Waste and spent materials shall be disposed of in accordance with EU and national legislative requirementsthrough the services of an authorised disposal organisation - whose advice shall always be sought.WARNINGWhen making up solutions, never pour water into acid. Always add acid in a slow steadystream to a stirred solution. An exothermic reaction can heat the resulting mixture. If this occurs, personalcontamination hazards will be intensified. Take great care.5 Initial preparative techniques5.1 GeneralWhen safety critical structures are being bonded, optimum treatment is always necessary. This requires the use ofappropriate techniques to both clean and modify the surface; which itself can be either an inorganic or an organiccoating - or even a combination of both. By contrast, when joints are only to be lightly or nominally loaded the useof adhesives capable of dissolving light oils can allow minimal, or even no, surface preparation. The manufacturer’sadvice shall always be sought.It is useful to mention that only a few paint surfaces are capable of supporting anything other than purely nominalloads. The exceptions are typically those based upon the aqueous, electrochemical paints - such as those used inthe automotive industries and the epoxy and polyester based paints used during the preparation of ‘pre-coated’metal sheet.NOTE 1Elastomeric materials, which are also shaped by flow, are not considered as plastics.NOTE 2In some countries, the use of the term 'plastics' as the singular form as well as the plural form is permitted (as in theEnglish language version).SIST EN 13887:2003
EN 13887:2003 (E)85.2 HandlingSurface areas, which are to be bonded, shall be handled as little as possible prior to preparation. After preparation,such areas shall not be handled directly at all. However, if this is unavoidable then clean. Lint-free cotton or nylongloves shall be worn.5.3 CleaningRemove oil and grease based residues using aqueous materials if possible. Non-ionic detergents give goodresults. Proprietary alkaline cleaners are particularly good for metals because
they cannot only removehydrocarbons but the more aggressive, stronger versions can also remove metallic soaps and salts. However,aluminium shall not be prepared with either a sodium hydroxide based cleaner or other alkaline material.Some proprietary mixtures are used hot, while others utilise either anodic or cathodic currents. Whichever cleaningagent is used, components shall always be rinsed thoroughly (see 6.3 d)) and dried in a stream of clean, warm, oilfree and dry air for about 10 min at 60 °C.If solvents need to be used to remove identification marks, or paint, then propan-2-ol shall be used whereverpossible. Alternatively, use a ketone (see clause 4). Solvents can severely damage some thermoplastic materialsby either dissolving them or initiating stress cracking. Polycarbonate, polymethyl methacrylate and ABS basedplastics are particularly susceptible in this latter regard.Ultrasonic cleaning can prove acceptable for the preparation of smaller components.Vapour baths are very effective and are recommended for the preparation of titanium and its alloys. However, theyshall be based on a closed system. See clause 4.It shall not be forgotten that some industrial processes can, and do, have a damaging effect on surfaces, bothduring and after their preparation. The use of equipment often releases deleterious dust, fume, and vapour into theair. Oil vapour, mould release agent sprays and the atmosphere of a plating shop are particularly detrimental.Consequently, surface preparation (and bonding) shall be performed in separate areas where such contaminationcan be avoided.5.4 StoringA distinction needs to be made between laboratory storage and the delays incurred during industrial production.The former implies performance qualification of either surface or adhesive. Where qualification is required, storageshall be maintained in an ambient atmosphere of (23 ± 2) °C with a relative humidity of (50 ± 5) %. Thecomponents shall be used within 8 h; except for those materials, such as mild steel, which are still liable toprejudicial oxidation. Such surfaces should be bonded as soon as possible after preparation and, before bonding,shall always be kept under defined conditions such that contamination shall be impossible.Industrial production requires that minimum performance standards be maintained. To this end, procedures shallbe established such that the integrity of a prepared surface is not unacceptably prejudiced prior to assembly.Particular regard shall be paid to the possibility of damage occurring through oxidation, condensation andcontamination – particularly by release agents who shall never be used in the same building. Ideally, parts shall bebonded immediately after preparation and only exceptionally after 4 h.6 Surface modification6.1 Physical: Mechanical (scarification)6.1.1 GeneralScarification, the shallow roughening of both metallic and plastic (see 3.1) surfaces, using either abrasion orblasting, almost invariably improves the performance of the final bonded joint.Sometimes abrasion or blasting is required to smooth a coarse, rough surface, such as can be found on a casting,or simply to remove corrosion or other forms of contamination.SIST EN 13887:2003
EN 13887:2003 (E)9However, because of the possibility of inducing surface stress – eigenstress - scarification can be inappropriate foruse on thin, (6.1.2 AbrasionAbrasion can be effected either wet or dry using either a water resisting, coated paper (45 mm to 106 mm grit) or atridimensional, non-woven, abrasive.The following sequence is recommended:a) abrade straight across in a convenient direction until all the surface has been lightly and uniformly scarifiedthen ;b) abrade similarly, at right angles until all traces (from a) above) have been obliterated then ;c) abrade by means of a circular (above) have been obliterated and the surface appears uniform ;d) remove debris. If dry abraded, and if practical, use a vacuum. Otherwise, blow clean oil free and dry air in asuitably ventilated enclosure. If wet abraded, solvent wipe using a clean lint free cloth and allow to dry ;e) then either bond or implement a further surface modification process.If parts are to be bonded, then they shall be dry and shall be bonded as soon as practical (see 5.4). Drying can bespeeded by the use of a clean, warm, oil free and dry air stream at a temperature not exceeding 60 °C.NOTE 1Care should be exercised to ensure that abrasives do not become clogged and that contaminants are not beingtransferred from step to step through the above sequence.NOTE 2See 6.3 e) - the ‘Water break test’ - a procedure that demonstrates that a component’s surface is free ofcontamination.6.1.3 BlastingDry blasting is usually reserved for metallic components. However, when used carefully – to avoid excess erosion -the less aggressive processes can be effective when used on the more robust plastics. Proprietary processes areavailable. These encompass such specialised grits as particulate carbon dioxide and shredded nut husks.However, in the main metallic components are usually prepared by dry blasting with 45 mm to 106 mm abrasive grituntil the surface is uniform in appearance. Neither iron nor steel-based grits shall be used on aluminium,copper, stainless steel or titanium parts.Wet blasting, at an angle less than normal to the surface, using £ 20 mm grit - suspended in either water or steam -can be particularly effective on small metallic parts. Proprietary systems usually contain water-soluble additives.For this reason, the manufacturer’s advice shall be sought in order to prevent further contamination of the surface.Wet blasting is not yet recommended for titanium.Whichever technique is used, steps 6.1.2 d) and 6.1.2 e) shall be implemented and the notes observed.6.2 Physical: Non-mechanicalA number of processes have been developed whose purpose is to modify a surface without using eithermechanical abrasion or liquid-based, chemical techniques. Mainly, these are dedicated to bringing about abeneficial chemical modification of the surfaces of the plastics (see 3.1) by physically induced, oxidative processes.Some of these processes also introduce other chemical elements during the modification of the surface beingtreated. Some processes can also remove modest levels of contamination.The two major examples of these specialised methods are the flame and plasma discharge treatments. Asoptimum conditions need to be developed for both, it is suggested that appropriate techniques are devised inconjunction with an equipment supplier and a recognised investigative laboratory.SIST EN 13887:2003
EN 13887:2003 (E)10The following comments can be helpful:a) surface modification induced by an oxidative gas flame is a relatively simple, fast, effective and economicmeans of improving the surfaces of a wide variety of plastics. The method is particularly useful for preparingstrongly formed, three-dimensional components.However, it shall be noted that careful, automated control of the process parameters is essential and thatthese latter need to be selected in relation to the polymer to be treated and the component’s design.To obtain consistent results particular attention shall be paid to:¾ the gaseous fuel used;¾ the residual oxygen content of the flame;¾ the distance of the flame from the surface;¾ the rate at which the flame moves across the surface;¾ the standardisation of the time lapse prior to bonding ;b) similarly, plasma discharge, at ambient pressure – often called corona discharge - is fast, effective andeconomic. However, the technique has a restricted ability to cope with a varying component topography.Consequently, equipment can be troublesome to adjust and performance maintenance can be difficult unlesscomponents are simple in shape and essentially flat;c) low pressure, plasma discharge processes can be considered to be more versatile in their nature than the useof flame oxidation. Complex shapes generally present no problems and surface modification can be optimisedby the use of different gas combinations in the discharge chamber. However, the attractiveness of thetechnique is diminished by the high capital cost of equipment and the fact that, unlike gas flame and coronabased methods – which can be run continuously, plasma chambers require a batch based process;d) lasers have been used to prepare both plastic and metal surfaces. However, as the technique is not yetconsidered to be sufficiently well developed it should only be considered when there are no alternatives ;e) none of the foregoing methods involves liquids. Therefore, the need to dry treated surfaces is avoided.However, according to the process used, the nature of the surface itself and the ambient environment, themanner of surface deterioration will vary. Some combinations of the foregoing variants can be very tolerantbut, in principle, all surfaces shall be bonded as soon as practical after treatment (see 5.4). All processes shallbe standardised and, wherever practical, should be automated.6.3 ChemicalUntil recently, the usual object of the wet, chemical treatments was to oxidise a surface. However, as oxidationusually requires the use and disposal of powerful oxidising agents, alternative approaches using coupling agentshave been, and are still being, developed. To date, they have tended to be based upon silane chemistry. Theseprocesses, which are largely proprietary, are discussed separately in 6.4. See also clause 4.The effectiveness of the chemical based surface modification processes depends upon the maintenance of theintegrity of the individual process. Professional advice can prove advantageous especially in relation to themaintenance of etch solutions. The following requirements shall be observed:a) the water used shall be either distilled or de-ionised and shall not contain more than 50 mg/kg of solids. Its pHvalue shall lie between 6,5 and 8,5 and its conductance shall be less than 20 mS;b) solutions shall be made up accurately (technical or reagent grade materials ; with a limit deviation of ± 1 %)and maintained by means of periodic sampling, analysis and relevant documentation;c) waste and spent materials, chemicals and solutions shall be disposed of in accordance with legal requirementsand through the services of an authorised disposal organisation - whose advice shall always be sought.Whenever solutions need to be made up, or utilised, then, with the possible exception of the sodiumSIST EN 13887:2003
EN 13887:2003 (E)11naphthenide solution (see 7.3.7.2), equipment made from only polyethylene, polypropylene ortetrafluoroethylene shall be used;d) rinsing shall be conducted by either spraying or dipping in a constantly refreshed water tank - seerequirement a). In both cases, the action shall be sufficiently vigorous to ensure thorough removal of allresidues;e) where appropriate, or required, the "Water-break" test is to be used to indicate whether the surface is clean. Itis conducted by immersing the surface in water – see requirement a). Following withdrawal, the ensuing waterfilm shall remain continuous and unbroken for 30 s. If this condition is met the surface can be assumed to beclean and in an optimum condition for bonding. However, although long-term durability will be enhancedimprovements in bond strength should not be anticipated.SIST EN 13887:2003
EN 13887:2003 (E)12Table 1 — Basis of preparative method for metals and alloysMetals and AlloysProcedureNotesAluminium and alloysDe-grease (5.3) and scarify (6.1), then either bond as in7.2.2.1., method 1, or use a coupling agent or etch,
as in7.2.2.1. methods 2 and/or/to 4.Of these pr
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