Surface treatment gives aluminium profiles an extra dimension

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Discover the possibilities!

Surfaces are perceived in different ways. Colour, structure and gloss

contribute towards creating an impression on those looking at or feeling the

surface. The surface impacts greatly on giving an object its character.

Aluminium is a superb material in several respects. Through extrusion it

is possible to create complex forms with integrated functionality that are

difficult to achieve in any other way. Aluminium is the material of almost

unlimited possibilities.

In this brochure we will explain how extruded aluminium profiles can be

surface treated. How different surface treatment methods can be used to

create different properties, decorative as well as functional.

The options are numerous. We will willingly help you choose the most

appropriate surface treatment method.

The right surface gives your profile an extra dimension!

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Aluminium can be surface treated in many different ways

There are many different methods to surface treat aluminium. At Sapa we have divided these into four main

groups: anodising, powder coating, special surfaces and mechanical surface treatment.

Anodising refines the natural properties of aluminium and gives a decorative transparent surface with a high level of

corrosion resistance and which can also be coloured in different shades. The feeling of metal is maintained and the

finish takes on a beautiful lustre with depth of colour. As the anodised layer is transparent the surface is given a finish

with the help of mechanical processing, for example, grinding. The surface can be made matt, semi-matt or glossy.

The process gives a natural hue, which makes the surface living and interesting to look at. Sapa has the facilities to

offer natural anodising on aluminium profiles up to 20 metres long.

pages 6-9

Powder coating permits virtually unlimited colour options with very good colour harmony. Today powder coating is

easily the most dominant colouring method and provides UV and corrosion resistance and outstanding resilience to

wear and impact. A colouring method that has become more and more popular is the Decoral method, which makes

it possible to produce patterned surfaces, for example, different wood and stone surfaces.

pages 10-13

The special surfaces group comprises a number of different methods of which the most common are Sapa HM-

white, laminating and different functional surfaces, for example, hard anodising, different coatings or chemical

surface conversion. Sapa HM-white gives a dense and dirt-repelling surface with very good chemical and corrosion

resistance. Laminating involves applying a thin surface layer of veneer, foil or laminate to the aluminium surface.

You can make “wooden” structures with all the possibilities offered by the aluminium profile. Hard anodising gives

a significantly thicker oxide layer than conventional anodising and is ideal for components requiring hard wearing

qualities.

pages 14-16

The fourth group is mechanical surface treatment which primarily serves to give the aluminium surface an

appropriate structure and which is usually combined with other surface treatments such as natural and colour

anodising, lacquering, etc. The most common types of mechanical surface treatments are grinding, brushing,

polishing and blasting. Decor pattern, which is not really a surface treatment method, gives patterned effects in the

form of decorative grooves and recesses and where these are created directly during extrusion. In doing so a smooth

surface can be made more living.

page 17

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“We aim to represent good design united with practical functionality and high quality.”

Sven-Åke Nilsson, Dryson

“Different surface treatment options increase our flexibility”

Jörgen Frändfors, GSAB

GSAB is the leading wholesaler to the glazing industry in the Nordic region and offers a comprehensive range of in-house developed products in the form of sliding door systems, shower cabins, windows, etc, based on aluminium profiles. Jörgen Frändfors is a salesman and technical advisor at GSAB.

“When it comes to profiles for sliding doors, windows and other glazed products aluminium is the given material choice. The different surface treatment options on offer give us the flexibility to vary our products while maintaining profile solutions. We mainly use natural and colour anodising in different shades and HM-white. Both methods give a decorative surface that at the same time has a very high resistance to corrosion. For our shower range we also use bright anodising and for our conservatories we utilise powder coating, which gives us a large selection of colours.

What I like about Sapa is their whole-hearted commitment and their ability to pull the stops out when necessary. In addition, I appreciate my extensive contact network at Sapa, which means that I always can get quick and accurate answers to all my questions.”

Dryson specialises in towel dryers. The product range includes numerous different designs produced at the Dryson factory in Karlskrona. Sven-Åke Nilsson is managing director and also bears responsibility for the development of new products.

“We aim to represent good design united with practical functionality and high quality. The current trend is for design to take on a greater significance in the modern home, not least in the bathroom. Our new towel dryer Velvet is an example of our approach to meet market demands.

Velvet fully utilises the potential of the aluminium profile. Partly to attain a desired function based on as few component parts as possible. Partly to achieve a designed form and an attractive surface. The surface in this case is brushed and natural anodised.

Sapa, who I have known well for many years, have been thoroughly committed to the Velvet project. Through their experience and extensive knowledge of aluminium profiles they have actively contributed to realising our idea.”

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“We aim to represent good design united with practical functionality and high quality.”

“Our co-operation with Sapa only improves with time.”

Michael Holmström, managing director of Movomech

“Powder coating allows us to offer exactly the shade of colour the customer is looking for.”

Movomech develops, manufactures and installs system solutions for efficient handling in different production processes. The mechanical design of the equipment is usually based on the use of aluminium profiles.

“Our systems include close to 50 different aluminium profiles manufactured by Sapa,” says Michael Holmström managing director of Movomech.

“Our collaboration with Sapa stretches back over many years and it only gets better and better over time. We feel that Sapa makes a significant contribution towards the refinement and optimization of our engineering solutions.

When it comes to the surface finish of the profiles we use natural anodising and sometimes colour anodising too. The advantage of anodising is that the surface does not oxidize, but maintains its brightness and lustre. As our designs frequently incorporate rollers that roll in the profiles, the hardness and wear resistance of the anodised layer are immensely important.”

Ingvar Fäldt, Windoor

Windoor offers the market the broadest range of system developed balcony glazing and balcony rails. The products are prefabricated as far as possible at our Tranås factory. In addition to balcony systems, Windoor also manufactures products for window renovation.

“Balcony glazing has really become fashionable,” says Ingvar Fäldt, production manager at Windoor. “It’s not just the living comfort that increases, but also the value of the apartment.

A common denominator for all our systems is they are based on aluminium profiles, and Sapa in this context is one of our most important partners, partly as a reliable supplier, partly as a technical consultant concerning profile design. Around 85 to 90 % of our aluminium profiles are powder coated according to RAL and NCS standards. This gives us a unique potential to meet the demands of architects with regard to colour shading. We also use Decoral on our rails, a method that makes it possible to make an aluminium rail look like wood.

Aluminium profiles give us all the engineering design benefits we need. Our customers receive a product with maximal life span and minimal maintenance requirements.”

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ANODISING

Anodising gives a metallic surface that is hard and transparent

Aluminium oxide is aluminium’s natural protection against corrosion that forms as soon as aluminium

comes into contact with air. Anodising is a process that forms a significantly thicker aluminium oxide

layer than occurs naturally. In addition to the surface being aesthetically attractive, it is also very hard, is

resistant to wear and corrosion, and repels dirt. The hardness and transparency of the anodising layer

means that the surface can virtually be compared to glass. Furthermore, it is electrically isolating.

Natural anodised aluminium is completely uncoloured. Colouring can be done through spray/dip

colouring or electrolytic colouring. Spray/dip colouring gives an extensive choice of colour, while

electrolytic colouring offers a choice of colour from champagne to black and in lighter shades similar

to stainless steel or nickel silver. All anodised surfaces are available with different gloss values.

Anodised aluminium characteristics

Properties Natural anodising

Colour anodisingSpray-/dip colouring

Electrolytic colouring

Indoors Recommended Recommended Recommended

Outdoors Recommended Recommended for some colours

Recommended

UV resistance Very good Good 1) Very good

Corrosion resistance 2) Very good Very good Very good

Chemical resistance 2) Good Good Good

Wear resistance Very good Very good Very good

Adhesion Integrated with the base metal

Integrated with the base metal

Integrated with the base metal

Colour choice 3) Natural, uncoloured Large Range of brown, black

Colour consistency Very good Good Good

1) With spray and dip colouring the choice of pigment affects the colour´s UV-resistance.2) Different layer thicknesses are recommended when anodising depending on the environment the profile will be used in and the stresses it will be exposed to. Coat thicknesses less than 15 µm are not recommended for use outdoors. Normally a coat thickness of 20 µm is recommended.3) The choice of alloy and the coat thickness affect the gloss and hue of the colour. Other factors that affect how the anodised colour is perceived are the form and surface structure of the profile and the light and angle of the surface when viewed.

Note that the table is only a guide. Discuss with your salesperson which options are the best for you.

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Sting chairs are brushed and anodised in different colours. Natural anodised pillars used at marinas and camping grounds for water, electricity and lighting. Natural anodised yacht mast.

ANODISING

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ANODISING

Natural anodised clothes hanger.

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ANODISING

Colour anodising

Electrolytic colouring (HX)

Spray/dip colouring Gloss

Spray/dip colouring Semi-matt

HX10-UChampagne

HX20-ULight Amber

HX30-UAmber

HX40-UDark Amber

HX50-UBlack

SV50-I-GBlack

GD20-I-GGold

YW40-I-GYellowish-green

RC30-I-GRed cerise

OR35-I-GOrange

LI30-I-GLilac

BO35-I-GBrownish olive

BL20-I-GBlue

BG30-I-GBluish-grey

GN40-I-GGreen

BO20-I-GLight brownish olive

RD25-I-GRed

YW40-IYellowish-green

OR35-IOrange

RD15-ILight red

GD20, GD30, GD40-I, UGold

RC30-IRed cerise

SV50-UBlack

BL30-UBlue

LI25-ILight lilac

BG30-IBluish-grey

LI30-ILilac

GN40-IGreen

BL20-ILight blue

BO20-ILight brownish olive

BO35-IBrownish olive

RD25-URed

HX-RL-UStainless

HX5-UNickel silver

Natural anodising

NA 5-25 µm

The printed colours do not correspond to the true anodised colours. Ask your salesperson for a colour sample. These samples are pressed in alloy 6063-T6. Gloss samples are pressed in alloy 6463-T6. Spray/dip colouring is available in more colours than shown here. Request a quote!

Matt, semi-matt or gloss.

Significance of the letter codesGD Colour designation20 IntensityI Intended for indoor useU Can also be used outdoors G Bright-anodising

Coat thickness Use

25 µm Where surfaces are exposed to severe stress in the form of corrosion or abrasion.

20 µm Great or normal stress outdoors (e.g. transport and construction industries). Indoors – great stress arising from the use of chemicals (e.g. the foodstuffs industry).

15 µm Severe abrasion, indoors and outdoors in dry and clean atmospheres.

10 µm Normal stress indoors.

5 µm Protective anodising before machining, short period of etching.

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PAINTING

1) Depending on the environment the product is to be used in, it is possible to choose a powder type that conforms to stringent demands on UV and chemical resistance. Powder coating is available in several forms, including two types of powder – polyester and epoxy. Polyester is more appropriate for outdoor use and epoxy offers greater chemical resistance. There are also mixed powders available that combine the properties of the polyester and epoxy powders.

Powder coating offers a large selection of colours and patterns

Powder coating allows a virtually unlimited choice of colour for aluminium profiles. Sapa offers powder

coating and Decoral that gives patterned surfaces.

Powder coating is easily the most dominant colouring method for aluminium profiles and is suitable for

both indoor and outdoor use. Characteristic properties include good resistance to impact and wear as

well as excellent UV and corrosion resistance. The good adhesion and workability in some cases permit

product forming, for example, bending, after powder coating. The powder coating method gives high

repeatability. Apart from standard colours according to RAL (some 200) and NCS S (some 2000) we also

offer customized colours as well as structured finishing, metallic and clear lacquers.

Decoral is a development of powder coating that gives patterned surfaces. First a specially compounded

powder paint is applied, then pigment from a film is transferred to create a pattern. The technology

ensures deep penetration into the powder coat and gives a surface that has the same excellent

properties as typical powder coating.

Sapa’s powder coating facilities are certified according to the GSB standards, which means the

products as well as the processes conform to stringent requirements. Besides the continuous inspection

of production, 15 daily tests are made in a separate measurement room where the results are filed to

support traceability.

Powder coating characteristics

Note that the table is only a guide.

Properties Polyester Epoxy DecoralIndoors Recommended Recommended Recommended

Outdoors Recommended Not recommended 1) Recommended

UV resistance Very good Good 1) Very good

Corrosion resistance Very good Very good Very good

Chemical resistance Good Very good 1) Good

Wear resistance Very good Very good Very good

Adhesion Very good Very good Very good

Colour choice Very large Very large Very large

Colour agreement Very good Very good Good

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Powder coated profiles used as a balcony rail. Powder coated profiles as roof rails.

PAINTING

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Powder coated profile on a lamp.

PAINTING

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There are no limits to the number of patterns and colours. The Decoral method makes it possible

to achieve optional photographic reproduced patterned surfaces, for example, different wood and

stone surfaces. The pattern penetrates deep into the paint and assures that the result becomes

a surface that has all the excellent properties that characterise traditional powder coating. The

Decoral method has been used in mass production since 1996. The method is documented

through a number of laboratory tests as well as being tried and tested on different products.

Powder coating

Powder coated

Decoral finish

PAINTING

Dark oak Light oak Birch Red beech Light beech

Mature Pine White Marble Alder root Optional patterned surface

Own choice

Anodised profile Optional surface

Patterned surface with Decoral

Walnut

Apart from standard colours according to RAL and NCS S we also offer customised colours. RAL 3000

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SPECIAL

SURFACES

HM-white is ideal where there are large stresses, for example, harsh outdoor environments.

Sapa HM-white gives a UV resistant surface with a uniform coat thickness

Sapa HM-white is only available in a white finish and can be seen as a complement to colour anodising

as this cannot be produced in white. Sapa HM-white is characterised by a high surface finish and an

even and fine gloss.

Colouring is done according to the Honnystone method and is a combination of anodising and

lacquering. The colour layer, which is not much thicker than with anodising, is integrated in the surface,

which results in superb adhesion and coverage on all sides.

Coat thickness is evenly distributed across the surface, even over sharp corners. The tight measurement

tolerances make HM-white especially suitable for parts that are assembled after surface treatment,

for example, those with a snap-on function or hinge joints. The UV resistant surface with its very good

corrosion resistance and gloss fastness makes HM-white also suitable for harsh outdoor environments.

Sapa HM-white characteristics

Note that the table is only a guide.

Properties HM-whiteIndoors Recommended

Outdoors Recommended

UV resistance Very good

Corrosion resistance Very good

Chemical resistance Very good

Wear resistance Very good

Adhesion Integrated. Very good

Colour choice White

Colour agreement Very good

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Laminating can turn the aluminium profile into a wooden profile

Laminating involves applying a thin surface layer of veneer, foil or laminate to the aluminium profile.

Veneers are available in virtually all types of wood; varnished, stained or untreated. Foils and laminates are

available in a large number of standard decors and can also be matched in special decors and colours as

requested. Precise pre-treatment of the aluminium profile in combination with a special adhesive ensures

good bonding of the surface material.

At the same time as a desired decor is obtained, the method utilises the technical possibilities offered by the

aluminium profile to produce thin walled, form stable models such as screw pockets, snap-on and hinge func-

tions, corner joints, etc. Application areas include furniture, floor and decorative mouldings.

SPECIAL

SURFACES

Veneer laminated profiles.

Examples of laminated surfaces.

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SPECIAL

SURFACES

A heatsink for cooling circuit boards that are nickel tin treated.

Hard anodised rails for car seats.A hard anodised part used on glass bottle production machines.

A functional surface is a surface that satisfies special functional demands

An aluminium profile can be surface treated in a number of different ways for different specific needs. Examples of different functional surfaces and their properties include,

Hard anodising gives a durable surface with a thicker oxide layer and less porosity than conventional anodising. By anodising the profile at a low temperature a surface layer with very high resistance to wear and tear is produced. The hardness is usually 400 - 600 HV. The coat thickness is generally significantly greater than for standard anodising, approximately 25 - 80 µm. In addition, excellent corrosion resistance and electrically isolating properties are obtained. Most alloys can be hard anodised. The hard anodised layer gives a dimensional increase that must be taken into consideration on components requiring high dimensional accuracy.

Tufram is a hard anodised layer that is impregnated and surface treated with selected fluorine plastic materials. Through subsequent heat treatment an extremely strong bond is created between the aluminium oxide and fluorine plastic. Several variants of the method are available of which each one is optimised to produce one or more of the characteristics: surface hardness, durability, corrosion resistance, low friction and good electrical isolation. The fluorine plastic gives permanent lubrication, durability and withstands continuous use at temperatures from -220 to +350 °C.

Laser cladding involves hard particles, for example, silicon carbide, tungsten or diamonds, being baked into the surface coat, which gives low friction, good resistance to wear and a high bearing capacity on the surface.

Plastic coating gives an area with high or low friction, protection against wear, chemical resistance, electrical isolation, noise damping, grip friendliness, corrosion resistance, UV-resistance, and resistance to wear and impact.

Rubber coating gives improved wear characteristics, high friction and acts as a damping material.

Metal coating with e.g. chrome, tin, nickel, silver or copper is carried out to give the required characteristics or functionality such as corrosion resistance, decorative appearance, hardness, wear resistance, electrical conductivity, temperature resistance, good slide properties or solderability. Nickel tin gives a solderable coating that is electrically conductive and protects against corrosion. During chemical nickel-plating a nickel coat is deposited chemically, which gives an extremely uniform coating independent of the component’s appearance, a very hard surface and effective corrosion protection.

Chemical surface conversion is used to treat parts when you need to guarantee electrical conductivity or as a pre-treatment method before powder coating and bonding. The most common methods are chromating, iron phosphating and zinc phosphating. Chromating is now usually replaced by a chrome-free passivation due to environmental considerations.

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MECHANICAL

TREATMENT

Towel dryer. The surface is brushed and anodised. Speakers where the cabinet is an aluminium profile which is brushed and anodised.

Foot board that is glossy, bright-anodised and features a decor pattern. Decor patterned and natural anodised profiles.

Mechanical surface treatment gives the surface the desired structure

Different forms of mechanical surface treatment are used to give the aluminium profile a desired surface structure and to improve surface quality. Mechanical surface treatment should be combined with anodising or clear lacquering.

Grinding/brushing leaves marks in the surface which can be very fine, medium or coarse. The surface is given a slightly silky, matt finish.

Polishing gives a smooth, bright surface.

Bright polishing gives a surface with a specular finish and a highly reflective quality.

Blasting gives a uniform, matt and coarse mechanical surface structure.

Tumbling is used to treat small components. Barrel polishing gives a smooth, bright surface. Barrel deburring removes burrs from e.g. sharp corners.

Decor patterns make a smooth aluminium surface more livingDecor patterns are not a surface treatment in the true sense of the word, but a patterned effect that is added by the designer when developing the profile. The profiles can be given an individual decor by using grooves or recesses. A suitable designed surface pattern also protects the profile against handling damage or can conceal a joint.

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This is how Stefan Borselius and Fredrik Mattson describe their co-operation with Sapa:

We were very happy when Sapa gave us a positive answer

“It all started with a educational visit to Sapa in Vetlanda. We were immediately inspired, both by the

possibilities of the extrusion technique and by aluminium as a material. On the way home we started to

outline different ideas,” say furniture designers Stefan Borselius and Fredrik Mattson.

“After a few months the ideas had taken shape and we decided to continue and try to develop a chair.

The conditions we agreed on were that the chair should be stackable and possible to interconnect. It

should blend into any environment, be exceptional in its design yet still inexpensive to manufacture. We

wanted to arrive at a slender form and express the simple thought, one profile for the back, one for the

seat and then fastening with the help of leg runners.

We contacted Sapa and it did not take long to get their technical experts fully involved. A number of

extrusion difficulties were encountered due to the profiles’ width in combination with the thin material, only

two millimetres in the thinnest parts. However, the people at Sapa solved the problems – when we were

on the verge of giving up. We were extremely relieved when we received a positive response just before

the deadline.

For the surface treatment on the Sting chairs we chose anodising, which allowed us immense variations

in colour. In relation to powder coating, the anodised surface gave more depth and lustre, which

accentuated the form of the chair. In addition, anodising is extremely durable, which is an essential quality

when working with furniture for a public setting.

As designers we like to work with many different materials, but aluminium attracts us for numerous

reasons and we have several new products in mind. In co-operation with Sapa we are convinced we can

set new limits,” conclude Stefan and Fredrik.

Lars-Göran Borg is a designer at Sapa’s Technical Service:

“None of us at Sapa imagined the adventure that waited. It has been extremely stimulating to work with

ideas men like Fredrik and Stefan. They have truly utilized the possibilities that extrusion and the material

offer. The result has been a light and elegant design that can be produced cost effectively.”

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Contact us when ideas are in their infancy

Aluminium is a material with few limitations, yet significantly more possibilities. The extrusion technology

gives developers and designers a large amount of freedom, both with regard to form and function.

Aluminium profiles are also easy to process and refine in different ways.

The idea of this brochure has been to give a quick summary of the most common methods used to

surface treat aluminium. We have shown examples of the possibilities with different surface treatment

methods, which we hope you can benefit from in your creative work.

Naturally, we cannot go into greater detail on just a few pages in a brochure. However, you are extremely

welcome to contact your salesperson or Technical Service as soon as you wonder about anything that

concerns aluminium profiles. To be able to contribute with our know-how and our experience is dear to

our hearts.

Despite working with aluminium profiles for many years, we never cease to be amazed by all the fantastic

design solutions from creative developers and designers. And best of all, nearly all the ideas we look at

can be implemented.

Contact us, and together we can realise your ideas.

We are shaping the future

Sapa Profiles UK Limited

Saw Pit Lane, Tibshelf, Alfreton, Derbyshire DE55 5NH

Tel +44 (0) 1773 872 761

Fax +44 (0) 1773 874 389

Tewkesbury Road, Cheltenham, Gloucestershire GL51 9DT

Tel +44 (0) 1242 521 641

Fax +44 (0) 1242 513 304

info.profiles.uk@sapagroup.com

www.sapagroup.com/uk/profiles

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