Organic coated steel
Contents
1. Polishing and sufficiently hard tools e g high alloy steels such as Z160CDV12 Z200CDV12 and Z230CDV12 4 are the most appropriate solutions Lubrication using a soluble or volatile oil to avoid the need for degreasing is a further possible solution However this requires increasing the blank holder pressure to reduce the greater risk of slippage and the associated risk of wrinkling It is advisable to locally increase the size of the blank in draping zones in order to minimize wrinkling With high production rates it may be necessary to cool the tool in extreme cases It should also be noted that high stretching or drawing strains may modify the surface finish and gloss of the coat ing These changes in appearance may be accompanied by a loss of corrosion resistance in aggressive environments moist and salt containing atmospheres etc Laboratory tests should be performed in such special cases 4 3 Roll forming The same factors are important in roll forming of organic coated steel i e the flexibility and adherence of the coating in bends and its resistance to contact pressure and friction The first of these aspects will be considered in detail later in the section dealing with design see p 29 For resistance to contact pressure the solutions are different from those applicable for drawing processes Firstly the diameter of the rolls must be as large as possible Secondly all sharp angles on the rolls must be elimi2. USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL Arcelor Group SMES E L OF R L AES We often wonder at the glorious colours and intriguing surface struc tures of the world s flora and fauna But everything in nature has a func tion to fulfil Colours are there to catch attention or warn against danger Surface structures capture light and oxygen perform a cooling function or provide protection from the rain In Arcelor FCS Commercial s organic coated materials you will find a similar symbiosis between function and design We design the surface proper ties and colours to meet very specific technical and aesthetic requirements And at the same time we ensure that our products are recyclable safe and durable Arcelor has opted for sustain able development out of respect for life Today and tomorrow Steel for life m USER MANUAL Organic coated steel Introduction 3 Advantages Organic coated products 5 21 The Arcelor product range 22 The coating line 2 3 Basic characteristics of organic coated steel General recommendations for use 9 3 1 Important notice 3 2 General recommendations 3 3 Recommendations for handling packaging and storage 3 4 Recommendations for decoiling slitting cutting to length shearing punching and mechanical cutting out Forming of organic coated steel 15 4 1 Introduction 4 2 Drawing 4 3 Roll forming 4 4 Bending 4 Panel forming 4 6 Edge forming 4 7
3. tochemical stability UV resistance resistance to soiling etc Of course there is no such thing as a universal organic coated product that can meet all these requirements but we have been able to develop special products for each type of application It is often necessary to give priority to one or more properties to the detriment of others The wide range of characteristics that can be built into organic coated products explains the diversity of the solutions proposed by Arcelor It is therefore essential to draw up precise prior specifications so that we can define the optimum solution in terms of technical and economic criteria ARCELOR FCS COMMERCIAL Arcelor Group General recommendations for use 3 1 32 3 3 3 4 Important notice General recommendations Recommendations for handling packaging and storage Recommendations for decoiling slitting cutting to length shearing punching and mechanical cutting out SERES E L F O R 10 10 11 12 L F E General recommendations for use 3 1 Important notice The sections below define an ideal processing line for organic coated sheets and optimum working conditions They suggest a suitable solution for every type of applica tion However they must not be interpreted as mandatory but rather as a guarantee of success A coil coated product and a method of processing should be chosen by selecting a suitable substrate cold rolled s
4. Spinning Joining organic coated steel 21 5 1 Adhesive bonding 5 2 Clinching 5 3 Riveting 5 4 Lockseaming 5 5 Joining with bolts studs clips etc 5 6 Welding Protection and manvfacturing aids 27 6 1 Temporary protective films 6 2 Lubricants and cleaning solvents Design 29 7 1 Shape design 7 2 Joint design 7 3 Design of edges and corners Post treatment 35 Today organic coated steel offers exceptional economic and technological advantages which explain its extraordinary success story in industry Introduction Organic coated steel products are used in all sectors of industry In building and construction profiles are used for wall cladding and roofing and also for applications such as suspended ceilings lighting etc In general industry these products have a variety of applications including metal furniture HVAC Heating Ventilating Air Conditioning and many others And of course in the domestic appliance market the advantages of organic coated steel products are well known They are successfully used for white goods refrigerators washing machines etc and small kitchen appliances microwave ovens etc Brown goods computer casings VCR amp DVD casings etc are another successful application The purpose of this document is to give you all the information you need to take maximum advantage of everything organic coated steel has to offer But it is no more than a technical support tool and not intended
5. avoid severe damage to the coating The best solution is to use an articulated punch and cam sys tem in which the punch can rotate in addition to vertical displacement This system also limits sliding during tool withdrawal The process configuration is somewhat similar to that of flap bending articulated punch blank holder die Edge forming flanging with an articulated tool USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL 4 7 Spinning Spinning is a process that can induce high forming strains and from this point of view it is similar to drawing In order to avoid damage to the paint coating the roll must have a large diameter and a perfectly polished surface The surface of the mandrel must be equally well polished to ensure that the steel sheet slides easily blank v tailstock uu spinning roller mandrel Principle of lathe spinning In difficult cases involving extreme deformation or high strength steel substrates etc the rotation and feed rates must be reduced to prevent overheating The organic coated steel can also be cooled with compressed air or lubricated with a soluble or volatile oil However the latter solution is only possible on a numerically controlled machine due to the projections When designing a new component the mechanical and aesthetic aspects of how it is to be assembled must be taken into account right from the beginning This point will be discussed
6. coated products The curing cycles are extremely important since they deter mine the quality of the paint system in terms of hardness adhesion and mechanical and chemical resistance 2 2 3 Exit section The strip passes through an inspection section and finally reaches the coiler Coil weights are adjusted to meet the cus tomer s requirements A number of different on line quality control tests are car ried out Coil coating lines comply with quality assurance standards such as ISO 9001 ISO 14001 and ISO TS 16949 The dimensions tabled below give the overall dimensional ranges They may vary according to the combination of product parameters specified Please contact us for more detailed information especially in cases where extreme thicknesses or widths are required Product Thickness mm Width mm Organic coated products 0 17 to 3 600 to 1850 Skinplate 0 25 to 1 1 5 600 to 1530 Colaminated products 0 4 to 1 1 5 700 to 1450 2 3 Basic characteristics of organic coated steel Organic coated steel is generally composed of a steel substrate cold rolled or with a zinc based metallic coating with a surface treatment layer a paint primer coating and a topcoat For certain applications a colaminated polymer film may be added anda temporary protective film if required USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL Topcoat Primer Surface treatment Zinc coating Steel Zinc coating Sur
7. for edge protection USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL The aesthetic appearance of sheet edges is not as good as in post painted products Different solutions can be envis aged such as 180 folds hems or the use of synthetic edge covers However it is generally preferable to modify the component design so as to locate the edges where they will not be visible for example at the back of the component or to ensure that they are covered by other parts Solutions using synthetic edge covers This problem also concerns corners since good corner appearance is often one of the specifications As before it is often possible to fold the corners so that the edges are not visible In drawn components the corners must be designed with large radii to avoid the risk of damage to the coating during the forming operation This aspect has already been discussed in the section on forming see p 15 Examples of designs with no visible edges Other solutions now exist for the forming of corners Wemo Eckold techniques etc Organic coated steel offers numerous advantages due to the many possible combinations For example steel sheets can have a different finish colour or appearance on each side or be painted on one side only etc Any request must be examined in detail since the paints applied on the two sides must be compatible in terms of curing temperature for example or to avoid the risk
8. has several advantages Since bending lever age is increased contact pressures are decreased in inverse proportion The bending or natural radius of the sheet increases thereby reducing the strain in the coatings The increased die entry radius also lowers contact pressures and friction V bending with narrow and wide dies Effect of the punch there are several different types of tools available The most commonly used type has a nose radius smaller than the natural radius of the sheet generally between 0 6 to 0 8 mm Other types have larger radii of the order of a few millimetres generating larger bending radii in the sheet and therefore greatly reduced deformation strains in the organic coatings see p 30 USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL 4 4 3 Forge bending Forge or impact bending in a V die is an extremely aggressive process and therefore not suitable for organic coated steel Fortunately this process is rarely used nowadays Its main advantage is simplified control of springback NB elastic springback depends solely on the steel grade used and is not altered in any way by the presence of organ ic coatings Finally particular attention must be paid to the tool dimen sions Certain tool manufacturers give tolerances of 0 02 mm for tools when new but it must be remembered that tools can age differently depending on their applications 4 5 Panel forming Panel forming is v
9. in more detail later However what may appear to be a difficulty may in fact be an opportunity to switch to cleaner and less noisy joining processes Joining organic coated steel 5 1 Adhesive bonding 22 5 2 Clinching 23 5 3 Riveting 23 5 4 Lockseaming 24 5 5 Joining with bolts studs clips etc 25 5 6 Welding 25 ARCELOR FCS COMMERCIAL Arcelor G Duo Slee E L CR L TEENS Joining organic coated steel 5 1 Adhesive bonding Adhesive bonding is ideal for organic coated steel which is an intrinsically clean product and an excellent substrate for adhesives In order to obtain good adhesion and cohesion in the bond the compatibility of the adhesive and the organic coating should be ascertained prior to use This question must be examined in detail since each organic coating adhesive combination has its own specific characteristics Moreover the durability of the bond may vary with the envi ronment to which the finished component is exposed Please consult Arcelor s specialists on this point An adhesive bonded structure is a complex composite system whose efficiency depends not only on the choice of adhesive but also on the cohesion of all the constituent layers Failure of a joint may occur in the adhesive in the metal or organic coating or at one of the interfaces metal metallic coating primer topcoat adhesive Tests must be performed to define the optimum technical and economic solution for each case An important p
10. reasons and for optimum corrosion resistance L B doy a Different single and double lockseams However lockseaming is only suitable for parts with a simple geometric design and cannot be used for corners The joints cannot be dismantled and have low resistance to sliding in a direction parallel to the folds and low resistance to open ing perpendicular to the folds With lockseaming folding strains are often severe requiring the use of extremely flexi ble organic coatings Lockseaming is economical for large series even though the design of the tooling can be lengthy and difficult 5 5 Joining with bolts studs clips etc These mechanical joining methods are also perfectly suited for use with organic coated steel They can be used to join products of completely different types without reducing their corrosion resistance The joints can be readily disman tled but are aesthetically unattractive even when covered by coloured plastic caps They represent a significant addi tional cost in terms of materials and labour Mechanical join ing of this type is relatively silent and consumes little energy but is difficult to automate Various mechanical joining techniques studs clips bolts etc 5 6 Welding In general conventional welding techniques have a nega tive effect on the appearance of organic coated sheet and lead to a loss in corrosion resistance Protection of the weld zones is therefore
11. required properties and perform ance levels must be defined and this will guide the choice of joining technique In practice it is rarely necessary to attain a performance level equal to that of spot welding to obtain a durable joint that is perfectly adequate for the requirements Details of the different joining techniques available for organic coated sheet are given in chapter 5 see p 21 Design 7 3 Design of edges and corners Many designers worry about corrosion resistance at edges and corners and on the sheet surface in the event of scratches In fact the corrosion resistance of organic coated steel is perfectly guaranteed by the presence of a sacrificial zinc based metal coating and a paint primer containing cor rosion inhibitors The application of primer coats on both sides enhances the corrosion resistance of the sheet edges Organic coated steel has all the necessary elements to ensure satisfactory corrosion resistance at least as good as for post painted sheet and distinctly better than a steel sheet with only a zinc coating In a few rare highly aggressive situations it can be an advan tage to fold the edges in order to prevent them from com ing into direct contact with a damp environment Rounded or drop shaped folds are to be preferred to fully flattened ones to minimise strains Another possibility for protecting highly exposed zones is the use of a sealing compound or similar product Solutions
12. steel will be the same as for post painted components The parts should be placed in boxes baskets or other containers in such a way that they are separated from each other and protected against damage due to friction or impact Corrugated cardboard spacers foam sheets or other similar products can be used for this purpose Parts must never be stacked in bulk without individual packaging 3 3 3 Storage The coils sheets or blanks must be stored in clean heated premises which must be at least sufficiently ventilated to prevent moisture accumulation If storage at a low tempera ture cannot be avoided the products must be heated at about 20 C for 24 hours prior to processing see p 10 Coils should not be placed directly on the ground but on protective mats made of rubber felt or similar materials to prevent rough surfaces or debris causing marks or inden tations on the first lap of the coils Coils and bundles of organic coated strip must not be allowed to splay or be stacked on top of one another The protection should be replaced on all partly used coils and bundles in order to avoid soiling and damage to the exposed laps or sheets It is recommended to use organic coated products within six months of manufacture in order to conserve maximum flex ibility of the organic coatings After six months a mechanical densification of the structure of the organic coating may occur leading to loss of flexibility General recommend
13. the stack while the sheets are removed one by one Suction pad systems for handling sheets and blanks With handling systems whereby the steel is manipulated between tools roller tables stackers etc the tools should make contact with the steel without slipping Alternatively contact should be made with a soft surface The use of plas tic transport rollers or rubber conveyor belts are possible solutions The principal requirement is to ensure a soft con tact surface that does not retain dust Manual or automatic handling operations may never involve sliding one sheet or component over another Finally when other handling systems are used e g forklift trucks it is often sufficient to add a sheet of felt or rubber to comply with the handling requirements for organic coated products Experience has shown that it is preferable for organic coat ed products to be supported on their least vulnerable side during handling with the appearance sensitive front side facing upwards This also facilitates the detection of any surface defects USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL 3 3 2 Packaging Whatever the format coil sheets or blanks organic coated products are dispatched in packaging appropriate to the transport and handling conditions the destination and the intended final use This question should be examined with the Arcelor sales teams The packaging of finished parts made from organic coated
14. 35 and 100 um must be taken into account when determining clearances A thin film permits visual inspection of the product during processing A thick film will provide better protection for the steel but since it is opaque it will prevent adequate inspection The use of protective films imposes certain precautions dur ing outdoor storage If condensation is trapped between the film and the organic coating there is a risk of corrosion It is recommended not to exceed 6 months before removal of the film which must be performed at ambient tempera ture Film coated products must not be stored in sunlight nor at extreme temperatures Finally the film should be peeled off rapidly after severe forming operations such as deep drawing since high pressures lead to a loss of peelabil ity with time USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL 6 2 Lubricants and cleaning solvents In cases where lubrication is necessary it is important to choose the right lubricant Volatile oils are to be preferred since they generally eliminate the need for degreasing In some cases they may be directly compatible with a final adhesive bonding or painting operation They are applied using low pressure microspray or aerosol systems or by roll coating etc Another solution is to use soluble oils However they require more complex installations for their recovery and treatment Greases waxes and similar products should be avoided since th
15. AL Organic coated steel ARCELOR FCS COMMERCIAL Organic coated products 2 1 The Arcelor product range 6 2 2 The coating line 7 2 3 Basic characteristics of organic coated steel 8 ARCELOR FCS COMMERCIAL Arcelor Group STEEL FOR LIFE Organic coated products 2 1 The Arcelor product range Today Arcelor can offer a complete range of organic coated products These fall into three categories Conventional organic coated steels produced in a contin uous process by applying liquid paint onto a substrate Laminated strip produced on the coil coating line by the application of a film onto a layer of adhesive Skinplate Colaminated strip produced on the coil coating line by applying a film directly onto organic coated steel Our range of organic coated steel products meets the requirements of all sectors of industry 2 1 1 Domestic appliances A very wide range of high gloss organic coated products is available for domestic appliances The substrates we use for these applications are cold rolled and galvanised steel Different steel grades are available for example for bending and deep drawing applications The organic coated steel to be selected for these applica tions depends on the end use as indicated in the table below In each case there are several possibilities Do not hesitate to consult us to help you choose the most appropriate product for your application Product Appearance Application Est
16. They can be correctly estimated by simulation using finite element software based on a preliminary geo metrical definition of the component They can also be determined experimentally by measurements on printed grids if the component already exists USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL Whatever the situation forming strains must be kept to a minimum to keep the widest possible choice of coatings open so that optimum compliance with the different prop erty requirements can be achieved The geometry must therefore have fillet radii as large as possible and the forming process must be adjusted blank holder pressure lubrication so as to avoid excessive tensile stresses in the sheet These choices also have a positive influence on the contact pressures exerted by the tooling on the organic coatings thereby reducing the risk of scratching or tearing 7 2 Joint design Joints must conserve the properties of the coatings and the visible areas must remain aesthetically attractive Since most types of organic coated steel have electrical insulating properties it is difficult to weld by resistance processes Arc welding processes involving complete melt ing are also problematic because of contamination of the melt pool by the coatings These factors limit the choice of joining processes in comparison with post painted sheets and the use of other assembly techniques is usually the best solution First of all the
17. aining the quality of the product two accumulators looping towers are used as buffers when the entry or exit section of the line is stopped for joining or cutting the strip 2 2 1 Entry section Coils are placed on a pay off reel To allow the process to proceed continuously the head of the incoming coil is stitched to the tail of the coil in process 2 2 2 Process section Pretreatment The surface of the strip is prepared for coating This pretreat ment is performed in various steps First it is degreased and then a surface treatment coating is applied to reinforce the adherence of the paint Coating process The first coating head applies liquid paint to both sides of the strip usually primer on the topside and backcoat on the underside The strip is then passed through an oven where the solvents are extracted and the coating cured After leaving the oven the strip is cooled and a topcoat is applied to the upper surface in the second coating head followed by another curing and cooling cycle Legend Pay off reel Stitching machine Degreasing Entry looper Pretreatment Coater primer coater top amp back Oven Cooling Coater top Coater bottom oat et TSK Oven Embossing roll Cooling Levelling machine Exit looper Inspection point Coiler SA a SA m iA Fach oven is equipped with a solvent incinerator USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL Organic
18. all stages of the product life cycle design when designing new products or production processes research teams take their possible environmental impact into account from the earliest stages of the project production organic coated steel is produced on industrial lines designed to meet the most stringent environmental regulations concerning surface treatments solvent emissions and the absence of harmful substances in the composition of the paint transformation using organic coated steel improves working conditions in the workshop by eliminating the use of solvents and the handling and storage of chemical products usage the use of organic coated steel entails no danger to the consumer or the environment in the various sectors in which it is used namely the construction business domestic appliances and industry recycling at the end of its life cycle organic coated steel is recycled just like any other steel product The main advantage of organic coated steel is its consistent quality Paint film thickness colour matching and surface aspect are reproducible within narrow tolerances from batch to batch The flexibility of the coil coating process allows us to produce a range of different surface finishes such as smooth orange peel grained textured or embossed which can be obtained in a wide choice of colours solid metallic pearlescent etc and the required degree of gloss anything from matt to high gloss USER MANU
19. as a substitute for direct contact with our technical and commercial teams ARCELOR FCS COMMERCIAL Arcel o Slee E L OTR L IMEEM Introduction Advantages economic ecological technological Coil coating lines provide high productivity and yield reducing the cost of applying an organic coating Line speeds are frequently around 100 m min For the user switching from post painting to organic coated material means that he no longer needs to invest in his own paint shop degreasing installations and other surface treatment equipment or the ensuing waste treatment The use of coil coated steel simplifies manufacturing operations and provides a drastic reduction in e manufacturing costs energy costs e manufacturing lead time e the financial cost of managing stocks raw materials chemicals and intermediate storage Furthermore the use of organic coated steel significantly reduces company taxes and insurance premiums All taxes related to waste treatment are elimi nated In some cases the move towards clean manufacturing can benefit from subsidies from the state and or the European Union Organic coated steel is certainly one of the products best able to respond to present and future environmental regulations Arcelor has opted for a proactive approach to the evolution of these regulations by building respect for the envi ronment into the life cycle of its organic coated steel products This strategy is pursued at
20. ated steel ARCELOR FCS COMMERCIAL 4 2 Drawing blank holder punch restraining draw bead die lockbead blocking bead Draw beads and other restraining systems must be avoided In the drawing process the surfaces of the organic coating are subjected to different loading configurations the major stresses being due to deformation and contact pressures The different deformation modes contraction expansion plane strain tension uniaxial traction and shearing each have specific effects Contraction or necking must be closely controlled since it causes an increase in thickness which can cancel out the permitted tooling clearances The strain levels must remain compatible with the deformation capacities of the substrate and the coatings Different deformation modes in a drawn component The pressures generated in drawing are relatively high and often reach 5 to 10 MPa Friction must be closely monitored since it can damage the organic coating seriously The use of draw beads and other restraining devices should therefore be avoided Hard spots on the tools e g due to poor machin ing or hardfacing in certain zones must be eliminated Similarly die entry radii should be increased as far as possi ble The clearances between the punch and die should always be equal to the total thickness of the organic coated sheet plus 5 to 10 depending on the case USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL
21. ations for use 3 4 Recommendations for decoiling slitting cutting to length shearing punching and mechanical cutting out 3 4 1 Decoiling The drive system for decoiling must be matched to the line speed in order to optimise product flow In extreme circum stances the drive system will also eliminate jerks and flapping and slipping of adjacent laps 3 4 2 Slitting cutting to length shearing punching and mechanical cutting out Slitting and other cutting processes for organic coated strip are performed using the same parameters as for other prod ucts It is essential to correctly adjust and sharpen the tools to avoid the formation of burrs and paint slivers Because there is no final painting operation to cover the burrs they will remain visible Paint slivers and built up edges can con taminate the tools Slitting cutting to length and shearing operations must be considered at the design stage to ensure that any burrs that may result do not affect the appearance of the finished product or present a safety risk cuts to the hands during handling etc The following rules must be respected in order to control the position of cutting burrs Ideally the sheet should be worked from the coated side i e with the front side which will be visible in the finished product uppermost in order to avoid peeling of the paint in the event of poor tool adjustment Symmetrical mounting of the slitting and edging wheels is to be pref
22. e to the organic coatings and no heat affected zones The only point sometimes requiring attention is the presence of a protec tive film which must be prevented from peeling during cutting Forming of organic coated steel 4 1 4 2 4 3 44 4 5 4 6 4 7 ARCELOR FCS COMMERCIAL Arcelor Group Introduction Drawing Roll forming Bending Panel forming Edge forming Spinning Sale E L F Oo R 16 17 17 18 19 20 20 L TENES Forming of organic coated steel 4 1 Introduction During forming of an organic coated sheet the appearance sensitive surface is in direct contact with the tools The reaction of the material to the forming loads exerted on the surface therefore depends on the behaviour of the organic coating and this must be allowed for by adapting the process parameters appropriately It is for this reason that it is recommended to use dedicated equipment and workshops with extremely clean machines and a working temperature at or above the glass transformation point Tg see p 10 In order to avoid scratches or even tearing of the coating in extreme cases the tool sheet contact areas should be increased in order to decrease the local con tact pressures and limit relative movements and friction between the tools and the organic coated steel Increasing the contact area is not always easy to do directly but can be readily achieved indirectly by polishing the tools Relative
23. erred top shaft bottom shaft Symmetrical mounting right top shaft bottom shaft Non symmetrical mounting wrong USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL The burrs are then oriented as shown in the diagram below top side 4 4 backside burr orientation Burr orientation after symmetrical slitting The vertical and horizontal blade clearances for slitting are defined in the following figure top shaft x vertical clearance crossover blade I lt horizontal clearance between steel bottom shaft Horizontal and vertical blade clearances in slitting Slitting quality is considered to be good if the distorted zone is small the shear zone occupies about a third of the thickness e the fracture zone is sharp with an angle less than 5 there are few or no burrs e there are no paint slivers or build up on the tools 6 distorted zone plastic rounding shear zone fracture zone horizontal s little or no burr formation clearance LE Morphology of the cut edges Cutting to length with a shear gives burrs oriented in oppo site directions on the front and rear edges of the sheet M V moving blade uncoiled strip gt Orientation of burrs in shearing This aspect is important since it means that it is essential to stack the sheets perfectly vertically The use of disk cutters and similar techniques should be ruled
24. ery similar in principle to flap bending and the same solutions can be employed Bending on a panel forming machine It is very easy to automate and therefore frequently used in integrated manufacturing lines It is not necessary to turn the sheet over to produce reverse bends and it is possible to work on all four sides of a panel by means of a simple 90 rotation Production times and handling of organic coated components are thus minimised Component with positive and negative bends Forming of organic coated steel 4 6 Edge forming The control of strain during edge forming is similar to that in roll forming and bending processes Tool work piece contact is different on the inside and outside surfaces of the bend On the inside contact occurs over a surface area and pressure is fairly light In contrast on the outside contact with the punch blade is often linear and pressure is more acute This is therefore where the potential difficulties lie To minimise this problem the tools must be polished and this is especially important for the punch Clearance must be sufficient to avoid crushing the paint layer The punch edge radius should be as large as possible blank holder punch die Edge forming by conventional flanging In the conventional wiping process elastic springback is controlled by ironing i e reducing the thickness of the sheet For organic coated steel the process must be modi fied to
25. etic Cold Smooth grained Cold appliances orange peel Estetic Hot Smooth orange peel Cooking Estetic Wet Smooth orange peel Washing Estetic Bright Smooth orange peel Domestic appliances USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL 2 1 2 Indoor building applications amp general industry Arcelor s wide range of organic coated products covers all indoor building applications and end uses in general indus try The steel substrates used for these applications are cold rolled steel hot dip and electrogalvanised steel Galfan and Aluzinc The product range for indoor building applications and industry includes coatings with very specific properties such as varnishes and primers suitable for use as a base coat and compatible with insulation foams or adhesives Please contact us for further information on these products and the dimensions available Product Appearance Applications Polyester Smooth Air conditioners presentation orange peel racks radiators casings Estetic Flex Smooth grained Boiler casings rolled parts roller blinds presentation racks Estetic Tex Textured Metal furniture shelves and shelving units body shells for domestic appliances Skinplate Smooth grained Lifts presentation racks doors ceilings Estetic Clean Smooth Cold rooms Orange peel Cold rooms replacing Gelcoat Estetic Lighting Smooth grained Lighting Estetic Ceiling Matt Metal ceilings capp
26. ey are difficult to destroy without the use of solvents which are often incompatible with the organic coatings Solvents such as isopropyl alcohol are the best choice for cleaning organic coated sheets if this proves to be neces sary Methyl ethyl ketone MEK and ethyl acetate solvents must be avoided since they can attack the paint coatings The simplest solution for cleaning these products is to use soapy water In order to successfully design a component using organic coated steel three aspects must be considered namely shapes joints edges and corners Other factors such as stiffness fatigue strength etc will not be considered here since they are not specific to organic coated steel ARCELOR FCS COMMERCIAL Arcelor Group Design 7 1 Shape design 30 7 2 Joint design 31 7 3 Design of edges and corners 32 E L RECEN R L TIMENS Design 7 1 Shape design Component geometry has a direct influence on the strain undergone by the metal during forming The choice of geometry therefore determines the feasibility of fabrication This aspect is now well understood and controlled by all designers in the case of uncoated galvanised and electro galvanised steel For organic coated steel the same principles apply but designers must also check that the organic coatings are able to withstand the deformations involved Organic coatings have their specific characteristics adher ence flexibility hardness corrosion res
27. face treatment Backcoat The choice of substrate has a direct influence on the processing performance and corrosion resistance of the organic coated product For good corrosion resistance a relatively thick sacrificial zinc based metallic coating is the best choice On the other hand if the essential requirement is an ability to sustain severe forming strains without crack ing thin and flexible crack resistant zinc coatings are to be preferred The surface treatment carried out at the beginning of the process section prior to coating ensures good bonding between the primer and the metal substrate The role of the primer is mainly to enhance the adherence of the topcoat and improve flexibility and corrosion resistance The topcoat and the colaminated film if used provide the required surface characteristics such as the final appear ance colour texture gloss appearance etc hardness and resistance to abrasion and ultraviolet radiation Depending on the required performance a single primer or double primer topcoat paint layer can be applied on one or both sides of the sheet The processing performance and other characteristics required will vary greatly according to the type of substrate and the paint system used These characteristics include paint adhesion flexibility hardness resistance to surface abrasion corrosion resistance appearance gloss foodsafe heat resistance shock resistance chemical resistance pho
28. g the flexibility of the organic coating and its forma bility during clinching A protective film may also be benefi cial in this respect but it must never be located between the two sheets to be clinched With regard to the appearance of the component each clinching point produces a hump and a hollow Since the static strength of a clinch is less than that of a spot weld a greater density of points is required The clinching tool must be perfectly perpendicular to the sheets and the punch must be precisely positioned with respect to the die The sheet thicknesses must be less than 3 mm with a ratio between the two thicknesses not greater than 2 USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL 5 3 Riveting Riveting of coil coated products requires no special precau tions in addition to those required for cold rolled galvanised or electrogalvanised steel There are three possible riveting techniques Conventional riveting whereby holes are drilled before the rivet is introduced and deformed x rivet Conventional riveting Blind riveting for which only one side of the joint needs to be accessible since the hollow rivet is deformed by a central shaft Different models exist including explosive head and thread ed shaft types or systems in which the head or shaft snaps Try Blind riveting Joining organic coated steel Self piercing rivets require only one operation since as the
29. ings internal panels Estetic High Tech Textured Consumer electronics decoders hi fi computers teletronics Estetic White board Smooth White boards 2 1 3 Outdoor applications in building and construction For these applications the substrate is usually galvanised steel Galfan or Aluzinc The choice of the paint system depends on the environ mental conditions to which the product will be exposed Product Thickness micron Appearance Granite HD 25 Smooth matt textured grained Granite HDS 25 535 Smooth pearly Granite HDX 50 60 Lightly grained Granite Farm Front 25 Smooth Back 35 Polyester 25 Smooth PVDF 25 35 Smooth Plastisol 100 200 Smooth embossed Skinplate 180 900 Smooth grained various textures Arcelor s range of organic coated steel products currently includes over 80 options There is a choice of different colours finishes smooth grained structured orange peel pearly metallic embossed striated etc metallic coatings and steel grades Each product has its specific characteristics and applications The appropriate choice is therefore crucial and should be made in close collaboration with Arcelor s technical and sales teams 2 2 The coating line A continuous coil coating line consists of three main sec tions the entry section the central or process section and the exit section In order to maintain a constant speed in the process section which is essential to maint
30. ir name implies the rivet itself pierces the sheet Sel piercing rivets The advantages of self piercing rivets are similar to those for clinching and the process also gives higher resistance to static loading However this technique is less suitable for thin sheets Riveting can be used to join different types of products without damaging the corrosion resistance of the coatings in any way Riveting methods are relatively quiet and have a low energy consumption However the joints cannot be disassembled and are aesthetically unattractive Nevertheless the processes can be easily automated making them competitive when compared with other mechanical joining systems although they are more expen sive than adhesive bonding clinching etc due to the cost of the rivets USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL 5 4 Lockseaming Lockseaming is a technique involving plastic deformation of the steel to make the join It is perfectly suitable for organic coated steel providing that the metallic and organic coat ings are chosen to withstand the strains generated in the folds Lockseaming satisfactorily preserves the corrosion resistance of the coatings and can be easily combined with adhesive bonding The joint can be made perfectly leaktight by the use of a sealing compound an adhesive or a rubber seal Wherever possible the seam should be designed so that the sheet edges are not visible both for aesthetic
31. ired properties and at the same time withstand the forming strains The ECCA and NCCA tests are used to define coating formability flexibility and adherence based on a 180 bending test Since coil coated sheets are often tested against these standards it is useful to know how the two different approaches correspond to each other ECCA index NCCA index Bending test g 06 E 15T 3T En 2T 4T 20 2 51 5T 17 ECCA European Coil Coating Association NCCA National Coil Coating Association USA Finally if the different bending processes are examined closely it will be seen that they are not all equivalent from this point of view Flap bending and panel forming process es generate very little interfering membrane strains in the sheet The neutral fibre remains at mid thickness and the coating is subjected only to the bending strain In contrast press bending displaces the neutral fibre towards the inside of the bend so that the coating is subjected to an addition al tensile strain In narrow punch V bending the neutral fibre is taken to be at 0 4 times the sheet thickness while in forge bending it is at 0 25 times the thickness from the inside edge This significantly increases the strain in the coating the only advantage being the limitation of elastic springback In the case of drawing spinning and other similar processes the strains in the coating are of both the bending and mem brane types
32. istance etc Some of them can withstand very high strains such as occur in 180 folds for example while others are less tolerant It is not always possible to combine the best performances for all properties However it is always possible to find an opti mum compromise that meets the specifications as closely as possible It is therefore important not to introduce unnecessarily high strains at the design stage in order to conserve the widest choice of coatings to obtain an optimum balance between the different functional property performances Roll forming bending panel forming and similar processes induce bending strains in the coatings at folds which can be correctly predicted from the formula t 2 0 t 2 Ri where t is the sheet thickness and Ri is the internal bending radius Definition of bending strains USER MANUAL Organic coated steel ARCELOR FCS COMMERCIALL However this formula underestimates the strain when the bending radius approaches the sheet thickness e g in 180 folds The curve below shows the strain values calculated with the above equation as a function of the Ri t ratio and demon strates the logarithmic influence of the bending radius strain 0 1 2 3 4 5 Rift ratio Bending strain as a function of the Ri t ratio Even a simple bending radius must therefore be chosen with great care The organic coating must be taken into account it must have all the requ
33. lectrically conducting coat ings and marks the rear side of the coated sheet The stud inert gas SIG process is applicable to all types of coating but causes significant coating damage Welding a pin by electrical discharge welding Protection and manufacturing aids 6 1 Temporary protective films 28 6 2 Lubricants and cleaning solvents 28 ARCELOR FCS COMMERCIAL Arcel Post EERE L OF R L MAES Protection and manvfacturing aids 6 1 Temporary protective films A temporary protective film applied as the steel leaves the organic coating line or at a later stage is an excellent way to reduce the risks of scratching during processing However it entails additional costs for both application and its removal which must be carried out at the latest possible stage This peeling operation is generally performed on the finished component often by the final customer if the film is left in place to protect the component until arrival However for complex shapes film removal can be a laborious process In certain cases the film may hinder processing for example in drawing except for specially designed films laser cutting and adhesive bonding Conversely films usually pose no problems for bending roll forming slitting cutting etc The usefulness of a protective film thus depends essentially on the protection required and the processing operations to be performed The thickness of the protective film usually between
34. movements depend on the forming process employed and it is often not simple to minimize them However the friction coefficient can be reduced Polishing of the tools is again an excellent solution and the use of appropriate lubrication e g a volatile oil is another possibility Organic coated sheets will then have a very low friction coefficient often less than 0 05 with steel tools In certain cases it may be useful to protect the paint layer by adding a tempo rary organic film This possibility must be examined as a function of the intended forming process The strain levels arising from the design of the component and the forming process must be compatible with the formability of the steel substrate the metallic coating when present and the paint system This aspect will be dis cussed in detail in the section on component design see p 29 The thickness to be taken into account when designing a forming process is the total product thickness steel metalllic coating paint protective film It is this value that determines tool clearances For thin gauges or applications requiring very precise adjustments if the thickness of the coatings is not includ ed in the calculation the coating will be crushed It is easy to make this mistake since the organic coated steel thicknesses set out in the standards are the thick ness of the steel substrate metallic coating but do not include the organic coating USER MANUAL Organic co
35. nated and replaced by fillets In order to prevent slippage the ideal solution is to have tools with counter rolls mounted on bearings This is a tech nically simple solution that creates no additional difficulty in terms of maintenance and the initial investment is only marginally higher Forming of organic coated steel The roll forming process As in the case of drawing tools particular attention must be paid to the roughness and hardness of the rolls The best roll materials are low or high alloy steels 35NCD4 100C6 Z200C13 etc quenched ground and if possible polished The application of a layer of chrome is the ideal solution Whereas lubrication is essential in roll forming of galvanised steel to prevent the coating sticking to the tools it is often not necessary for organic coated steel in view of the excel lent properties of modern organic coatings Furthermore with complex profile geometries it may be difficult to elim inate the lubricant A temporary protective film is an additional solution to facilitate roll forming and safeguard the organic coating This solution is frequently employed for wide sections such as those used in the building industry but can prove more difficult for complex profiles This point will be discussed further at a later stage For small roll formed profiles most tooling processes are designed with very small or zero clearances in order to ensure accurate dimensions Howe
36. necessary if the part is exposed to an aggressive environment However certain techniques such as electrical discharge welding of studs give good results without damaging the coating 5 6 1 Resistance welding Because of its non conductivity organic coated strip is not suitable for resistance welding except in the case of specific organic coatings which are described as weldable Their overall static strength is nevertheless of the order of 500 mW compared with 0 02 to 0 05 mW for electrogalvanised steel Electrodes with hemispherical contact surfaces facilitate pas sage of the current by localising the force The weldability range is generally shifted to lower currents representing an advantage for industrial processes USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL Welding can be facilitated by mechanically removing the coating at the points to be joined In a few rare cases the electrodes can be brought in contact with the bare or zinc coated sides of sheets painted on one side the painted sides being in contact with one another piece added electrode electrode front side initial current main current electrode electrode front side initial current main current Resistance welding in specific configurations This welding process involves no special difficulties with regard to the welding parameters compared with bare steel or zinc coated steel The electrode lifespan
37. of marbling pressure marks that can appear during storage In conclusion component design imposes or implies impor tant choices with regard to the organic coatings It is essen tial to determine the best compromise between properties and coating cost while meeting the specifications and com plying with processing requirements This is only possible if precise specifications have been defined based on the required functions and performances of the final product Co operation between component designers and Arcelor s technical and commercial teams is therefore a powerful advantage in ensuring the successful use of organic coated steel USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL A distinction must be made between organic coated steels with a fully finished paint system primer and topcoat and semi finished primer coated only Fully finished organic coated products can completely replace post painted steel sheet Unlike fully finished prepaint primer coated steel is designed to eliminate the need for any further surface treatment operations and is ready to receive one or more layers of topcoat liquid or powder paints For automotive applications these products eliminate the need for cataphoretic pretreatment Post treatment Excellent appearance paint adherence and corrosion resistance can be obtained with these products For example a primer coated sheet subsequently given an automobile topcoat s
38. oint is the fact that adhesive bonded joints in organic coated sheets present a much bet ter wet aging performance than uncoated metal or gal vanised surfaces Two component polyurethane adhesives are an excellent choice for many applications Adhesive bonding has numerous advantages Loads are spread perfectly as a result of the continuous bond created With certain specific products it can also perform sealing and vibration damping functions The joints have an attrac tive appearance and the substrates undergo no thermal or mechanical damage Polymerisation of the adhesive can be performed efficiently and rapidly by various techniques either chemically by means of a catalyst or activating agent or thermally by using an oven heating press induction infrared heaters etc In order to facilitate handling of components before poly merisation is complete clinching or other similar joining processes can also be carried out at various sites on the component USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL Adhesive bonded joints are generally lap joints m e m lt lt dom lap joint butt joint Recommended adhesive bonded joint configurations Shear tensile and compressive stresses are to be preferred to peeling and cleavage which should be avoided Before bonding it must be verified that the surfaces to be joined are dry and not contaminated with chemical sub stances oil grease etc or d
39. ommercial teams will be glad to help you establish the best solution on technical and economic grounds Training personnel Working with organic coated products requires great care on the part of the operators They must be made aware of the constraints involved and should be given specific train ing to this end They should realize that they are dealing with a high grade product requiring special care and differ ent working methods USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL Using an appropriate working temperature Successful processing depends on the flexibility and hard ness of the organic coating The following graph shows how the working temperature affects these properties flexibility physical properties hardness N temperature Variation of coating flexibility and hardness with temperature For the paint to be flexible and formable organic coated products must be processed at a temperature above the glass transformation point Tg This is normally the case when working in an ambient temperature of about 20 C If it is colder in the warehouse where material is stored the coils sheets or blanks should be transferred to a location with a temperature of about 20 C for 24 hours prior to processing In extreme cases the organic coated steel sheet can be heated locally by installing radiant infrared heaters on the processing line The advantage of this procedure is that it ens
40. out since they cause coating burns and generate chips and burrs For roll forming for example profilers will find hydraulic or pneumatic shears at the line exit preferable to circular or band saws Furthermore the choice of a suitable sheet handling system is important particularly on punching presses The new mini brush types are to be preferred to the old ball systems USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL 3 4 3 Laser and water jet cutting In laser cutting the gas used must be nitrogen Oxygen burns the organic coating and disturbs the laser beam leading to a loss of power and the appearance of burrs The choice of nitrogen increases the cost of cutting due to the high flowrates required pressure of 20 bars compared to 1 bar for oxygen If the sheet has a temporary protective film cutting can be performed in two passes one for the film and one for the organic coated material If possible the adhesion of the film should be sufficient to prevent peeling which could hinder the beam The best solution is generally to remove the film prior to cutting in order to conserve the excellent quality of a laser cut accuracy narrowness of the heat affected zone and absence of burrs Water jet cutting is very suitable for organic coated products and requires no special adjustments Since there is no source of heat and no contact with a tool this process gives an excellent quality cut with no burrs no damag
41. teel with or without a zinc based metallic coating which will meet the required specifications 3 2 General recommendations The first point to be borne in mind is that the surface condi tion of the final component is that of the coil coated sheet before processing The second point is that the weakest link in the processing chain will determine the quality of the final product Consequently great care must be taken with all processing steps in order to ensure a high quality final product For organic coated steel a good production process is one that keeps all the initial properties of the material intact Essentially this means the avoidance of excessive defor mation or damage to the surface so as to preserve the cor rosion resistance properties and attractive appearance of the product This can be achieved by observing a few basic rules Use of dedicated processing lines and storage facilities If workshops and equipment are used for different products such as hot rolled strip cold rolled strip galvanised strip with and without oiling there is a significant risk of contam ination It is worth making an economic assessment of the possible benefits of investing in dedicated equipment for organic coated material compared with what it costs to pro duce batches of different products on the same line includ ing down time for cleaning and or changing tools before organic coated material can be processed Our technical and c
42. ure of roll formed tubes It can be directly applied to organic coated sheets heated by induction but since it creates a wide heat affected zone in which the paint is degraded its use is limit ed weld seam weld point pressure roll V angle 5 to 7 induction coil tube travel impeder Resistance butt welding USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL 5 6 4 Laser welding This process requires precise assembly of the sheet edges in order to prevent disturbance of the laser beam by fume emissions produced by excessive contact with the sheet surfaces As in the case of arc welding it is possible to remove the organic coating along the weld line The principal advantage of laser welding is the narrow heat affected zone which is only a few millimetres Laser edge welding 5 6 5 Welding of pins Various processes can be used to weld studs to organic coat ed steel but the only method applicable to all types of organic coated steel whether electrically conducting or not is electrical discharge welding When the different welding parameters are correctly adjusted it is easy to conserve a perfect appearance of the coating on the side opposite to the weld spot with excellent corrosion resistance of the whole zone This makes the process extremely attractive The presence of slight splashes around the edge of the weld has no effect on the coating 1 The pulsed arc process requires e
43. ures that the organic coating has excellent formability while retaining the same degree of hardness and chemical resistance after cooling Providing inspection zones Product inspection and monitoring should always be per formed during processing in order to detect defects such as scratches or indentations at the earliest possible stage The ideal solution is to provide inspection zones with adequate lighting The topside of the organic coated steel which will be visible in the end product must be facing upwards Please note that the presence of a protective film may con siderably hamper inspection see p 28 3 3 Recommendations for handling packaging and storage 3 3 1 Handling Coils sheets blanks and components all need to be handled differently Equipment for handling coils should have a protective coat ing e g sheathed non metallic slings and grips or C hooks with a rubber or synthetic coating These tools must be used with great care to avoid any hard impact which could mark the product Operators should wear gloves when handling sheets manu ally to protect their hands from cuts This also keeps the sur face of the sheet clean For automatic handling numerous solutions are available including robotic suction pad systems etc An excellent sys tem for both sheets and blanks is four point seizure by suc tion pads This system can be further improved by installing permanent magnets at the stack edges to maintain
44. ust particles In the event of contamination they must be wiped with a clean rag or a soft brush then with a cloth soaked in isopropyl alcohol In extreme circumstances the contact surfaces can be protect ed with an organic film which should be removed just before bonding tension peeling cleavage Different types of joint loading It should be noted that the range of steel products that can be precoated on a paint line includes steel precoated with an adhesive which can be reactivated thermally 5 2 Clinching Clinching is an excellent method of joining organic coated sheets It enables us to join materials of a very different nature with out using additional products With suitable precautions see below it preserves the corrosion resistance of the coatings Clinching is a clean process which produces no fumes or slag It is relatively quiet and consumes little energy It can be readily automated and easily integrated into various types of manufacturing lines e g roll forming Finally clinched joints have good fatigue strength m Clinching The clinching capacity of a sheet is directly linked to the grade of steel employed In order to guarantee the attractive appearance of the clinched points local lubrication with volatile oil may prove necessary This will limit friction between the punch the surface of the organic coated steel and the die Here again heating is an excellent means of ensurin
45. ver this approach is not suitable for organic coated steel since a degree of clearance is necessary to avoid damaging the paint coating For wide profiles a clearance of one or two tenths of a millimetre is generally necessary for a sheet thickness of 0 7 mm As in drawing it is the total sheet thickness that counts including the organic coating and protective film USER MANUAL Organic coated steel ARCELOR FCS COMMERCIAL 4 4 Bending In bending processes deformation strains can be controlled in the same way as for roll forming However the manage ment of contact pressures depends on the bending process used There are three possible methods 4 4 1 Flap bending Flap bending is an excellent method in terms of the contact pressures involved since the pressure is spread over the sur face area of the flap Moreover relative movement between the steel sheet and the tools is minimised Principle of flap bending 4 4 2 Narrow punch V bending In narrow punch V bending the pressures generated are higher since the contact occurs along a line rather than over a surface area Furthermore the coated sheet slides over the die entry radii Narrow punch V bending Effect of the die the basic rule in V bending is to use a die opening 6 to 12 times the sheet thickness For bending organic coated sheet the higher value is preferable i e 12 times the thickness This is a simple choice involving no extra cost and
46. with readjust ment of the current remains of the same order or better than that for zinc coated sheets Values of 1000 to 1800 spots have been obtained with certain weldable organic products An audible clapping sound and fume emission can sometimes occur without disturbing the welding process or in any way modifying the quality of the joint Finally the mechanical strength of the weld spots is identi cal to that obtained with uncoated or zinc coated steel 5 6 2 Arc welding techniques In these different processes MIG MAG TIG plasma etc the steel is brought to melting temperature As a result the coatings are vaporised and contaminate the melt pool This can create open porosity in the weld seam or may generate projections MAG welding or interruptions of the arc TIG welding Joining organic coated steel The coatings are burnt in a wide heat affected zone around the weld Mechanical removal of the coating in the weld zone is preferable to eliminate these problems and for this reason butt welds are easier to perform than lap welds Certain positions of the parts during welding promote the evacuation of fumes lap weld fillet weld gutter position outside corner weld inside corner LA f weld buit weld edge weld Different weld configurations As a result these processes are generally not suitable for organic coated products 5 6 3 Resistance butt welding ERW This technique is widely employed in the manufact
47. ystem can attain a DOI level of 85 90 with a film tension of over 17 5 excellent wet adherence 0 ranking and level 2 to 3 gravel impingement resistance In the 3C test no blisters or degradation are observed at the scratch at the end of the exposure time These values enable primer coated sheet steels to be used for conventional appearance sensitive automobile components A significant advantage of these primer coated steels is the guarantee of a uniform primer layer on all surfaces of a component This is a big advantage in achieving corrosion resistance inside hollow components given the difficulties in controlling the electrical field with the cataphoretic coating in such cases ARCELOR FCS COMMERCIAL Arcelor Group Sales Ee L OTR L WES Arcelor has opted for sustainable development out of respect for life Today and tomorrow Steel for life Arcelor FCS Commercial 19 avenue de la Libert LU 2930 Luxembourg wwwees arcelor com fcs technical assistance arcelor com PR UM OCO EN 08 2004
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