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Metal Coatings


Metal Coatings ZINCALUME steel Roof sheeting made from ZINCALUME steel is available in a range of profiles. The zinc/aluminium alloy coating on ZINCALUME steel ... – PowerPoint PPT presentation

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Title: Metal Coatings

Metal Coatings
Why Powder Coat?
  • Elimination of VOCs - VOC is short for volatile
    organic compounds,
  • VOCs that escape into the air contribute to air
    pollution outdoors and inside our homes. ...
  • Elimination of HAPs Hazardous Air Pollutants.
  • Reduction of ESOH Concerns ( Environmental
    Safety Occupational Health)
  • Reduction of Hazardous Waste

Why Powder Coat - continued
  • Single component, solvent free material
  • life limitations - good
  • Process Efficiency
  • Quick cure time
  • Quick equipment prep and clean-up

Powder Coating
  • One of the most common methods of finishing metal
  • Many items used everyday are powder coated.

Examples of Powder Coating
  • Everyday items such as mailboxes, chairs,
    appliances, automotive parts, tools, and
    construction materials.

The Process
  • A simple process, involving spray painting a
    fine plastic powder paint onto a metal surface.
  • Typically the surface is steel, aluminum or iron.
  • Most any surfaces can be coated, however, they
    must be able to withstand the high temperatures
    of the baking oven.

Walk in oven
  • Before coating the part, the surface must be
    cleaned. Often a sand blaster is used for this
    purpose. Parts must be totally free of
    contaminants that might effect the process such
    as grease, rust, oils, etc.
  • As the powder leaves the gun it is charged with
    static electricity. This charge then attracts
    the powder to the surface that is being coated.
  • After the parts are coated, they are then baked
    in an oven at about 400 degrees Fahrenheit for 10
    to 45 minutes depending on the part. The actual
    part itself must reach these temperatures in
    order for curing to occur properly.
  • While in the oven, the powder melts and flows
    into a smooth finish. Curing time is critical,
    because under curing will cause loss of adhesion,
    and over curing will cause the strength
    characteristics of the powder to decrease.

  • Unlike painting, there are no runs or drips with
    powder coating, and due to the static charge,
    there is no need for primers.
  • Additional clear coating and primers can be added
    to improve protection and depth.
  • If a mistake is made before baking, the powder
    can simply be blown off with an air nozzle and
    reapplied. If the mistake is realized after
    baking, the part must be sandblasted or the
    coating must be burned off.

Types of Powders
  • There are two main types of powders used for
    different applications.
  • Both types outperform most wet paint finishes and
    they both come in many varieties of colors,
    textures, and glosses.

  • Most indoor powders are made of epoxy. Epoxy is
    the most durable powder, but it will chalk and
    dull from the suns ultraviolet rays.
  • Polyester powders are not as durable, but since
    they are unaffected by the sun, they should be
    used for most outdoor applications.

Equipment Used
  • Obviously the most important and expensive item
    to purchase is the oven.
  • The oven must be able to heat a part to around
    400 degrees Fahrenheit for at least 10 minutes,
    sometimes more depending on the part.
  • The size of the oven depends on the sizes of
    parts the consumer wishes to coat. Obviously the
    larger the oven, the larger the part that can be
  • With a larger oven, several parts can be baked at
    one time.

  • Ovens vary in style and price.
  • A small 6x 8x 10 walk in gas oven is priced
    around 30,000.
  • A 100 oven with a pass through conveyer can be
    as much as 100,000.

Small walk in oven
  • There are three main types of ovens gas,
    electric, and infrared. Infrared ovens work well
    if designed properly, however gas and electric
    tend to be more dependable. Electric ovens take
    longer to heat up, thus delaying the coating
    process. Obviously, the faster the oven heats,
    the faster the product will be coated.

Spray Guns
  • There are two types of spray guns,
  • Corona and a
  • Tribomatic spray gun.

Corona Gun Method
  • Powder is applied using hand-held gun featuring a
  • high-voltage electrode at the front end.
  • Theelectrode creates ions, which impart a charge
    to the
  • powder particles exiting the gun, and the charged
  • particles are attracted to the electrically
    grounded target part.
  • Benefits
  • Low film thickness possible (1.5 - 5 mils)
  • Limitations
  • Difficult to cover recessed areas and tight
  • due to Faraday Cage Effect

Tribomatic Gun Method
  • Powder is applied using hand-held gun designed to
    impart an electrostatic charge through friction
    between powder particles and gun internal
  • Benefits
  • Even layer deposition
  • Improved deposition into recesses
  • Gun does not produce the Faraday Cage Effect
  • Typically consumes 20 less powder than Corona
  • Limitations
  • Coats at half the speed of corona gun
  • Electron donor/acceptor tendency between powder
  • gun material must be great enough for adequate
  • charging of the powder

Other equipment needed
  • the powder supplies
  • an air operated vacuum cleaner to retrieve any
  • a spray booth.

Fluidized Bed Method
  • Parts are pre-heated and suspended in an
  • airborne cloud of powder coating material.
  • Benefits
  • Simplicity
  • Less waste, lower
  • cost
  • Limitations
  • Only coatings 10-
  • 100 mil are possible
  • Coating thickness
  • control is difficult

Electrostatic Fluidized Bed Method
  • Similar to standard fluidized bed system, but
  • is electrostatically charged and part is grounded
  • that particles are attracted to part surface.
  • Benefits
  • Preheating of part not required
  • 4-10 mil thickness of coating is possible
  • Small parts coated uniformly, quickly
  • Limitations
  • Inside corners tend to receive low film
    thickness due to Faraday Cage Effect
  • Part size is limited by container size

Drawbacks to powder coating
  • The major drawback is the initial investment to
    begin the operation.
  • Powder coating does not have the strength or
    hardness characteristics that some other coating
    processes such as chrome or zinc have.
  • Chipping is another main problem with powder
    coating. This often results because the part was
    not baked long enough or kept at the proper cure

Benefits of Powder Coating
  • The biggest benefit of powder coating is that it
    is environmentally friendly.
  • There are no solvents as in paints, and thus no
    harmful air pollution. There is absolutely no
    hazardous waste created with this process.
  • Economic
  • Overspray can be air vacuumed and reused, thus
    reducing the amount of waste produced as well as
    saving cost.

  • As can be seen for certain applications, powder
    coating is the most durable decorative finish
    available at this time.
  • A variety of different textures, colors, and
    glosses can be used.
  • The process is fairly simple and the cost is much
    less than other processes like chroming or zinc
  • Also the initial investment is minimal compared
    to other processes.

  • With all the benefits of powder coating, it can
    be seen why it is such a widely applied
    technique. Obviously, if a person has the
    resources and demand for the procedure, they
    should think seriously about investing in the

  • A powder coating material that will allow
  • us to overcome previous limitations of the
  • powder coating process resulting in
  • VOC, HAP and solvent free coating
  • reduced labour hours
  • lower costs

Tin plating
  • Tin plating is primarily for "functional"
    purposes such as providing a level of protection
    or corrosion resistance to a range of
  • Tin Plating is a lower cost alternative than some
    protective coatings. Tin also has a good level of
    conductivity enhancement properties (as opposed
    to silver which has higher conductivity) which
    may be of benefit to manufacturers seeking to
    enhance this property somewhat without adding too
    much to the price.
  • Tin has good solderability and is therefore a
    coating of choice where later soldering of
    components is required especially in the
    electronic fields.
  • Colour Aesthetics Tin plating has a 'whitish
    grey' hue and is usually applied without the
    layer of bright nickel used in decorative
    coatings - as such tin has a dull, or matt
  • commonly is used on lower value substrates such
    as mild steel or copper alloys.

Applications of Tin Plating Examples include
Low-tech electrical or electronic components such
as electronic connectors or bus bars commercial
cooking equipment parts requiring soldering
other. Substrates suited to this coating Tin can
be plated over most metal substrates .
Chrome Plating
  • is a very popular finish for many decorative
    applications, especially for the automotive and
    building industries in which there are many
    decorative trims and components. It also has
    industrial uses where, in conjunction with heat
    treated base materials it can provide a harder
    finish (hard-chrome).
  • Chrome plating is popular because it is hard
    wearing, bright and easy to clean. The nickel
    used in the coating process in conjunction with
    chrome provides high corrosion resistance. The
    nickel type used also determines the level of
    brightness. T
  • he chrome coating itself is stain resistant and
    abrasion resistant which is of appeal for
    decorative applications in heavier 'wear and
    tear' environments. T
  • here are alternative industrial uses for chrome
    plating (i.e. hard-chrome), sometimes used for
    surface maintenance on large tools or equipment.

Applications of Chrome Plating Automotive
decals, door handles and trims, tap-ware,
architectural fittings, racks, hubs wheels,
furniture and furniture trim, and many, many
other items.
Silver plating
  • Silver plating is an electrolytic process. Its
    properties can be utilised for either
    "functional" purposes such as enhanced electronic
    application or corrosion resistance, or,
    "decorative" purposes. Silver is commonly applied
    over preliminary coatings of copper and nickel
    though depending on the application this may
  • Benefits of SILVER Plating
  • Functional - Enhances electronic and radio wave
    conductivity. In a "high purity" form it is
    possible to achieve surface silver of around
    99.99 purity.
  • Applications of Silver Plating "Functional"
    coating examples include high-tech Electrical or
    electronic components such as antennas, bus bars,
    connectors. "Decorative" applications commonly
    include silverware (teapots, trays, trinkets,
    etc), jewellery or hand crafted art pieces.

Nickel plating
  • Nickel provides the 'substance' of the coating as
    it predominantly provides the hardness and
    corrosion resistance to the surface. Though
    sometimes used as a 'final finish' it is more
    common for nickel to be applied as the
    "undercoat" to final finishes such as silver,
    gold or chrome. The nickel solution type used in
    the finishing process determines the level of
    brightness of the finished product. Some nickel
    solutions result in a matt or 'satin' finish.
  • Benefits of Decorative Nickel Plating Nickel
    plating provides the finished product with
    hardness and protection from the elements and
    determines the level of brightness of the product
    - in fact it can be extremely difficult to
    achieve a bright finish without it.
  • Colour Aesthetics Nickel is a silvery colour
    with a "yellow/brown" hue. Nickel as a final
    finish can sometimes provide a closer match to
    some stainless steel grades - depending on the
    level of nickel contained in the stainless

Applications of Decorative Nickel Plating As an
"undercoat" nickel is used for most decorative
applications. It can also be used as a final
finish if required. A Class's "Restoration"
divison has assisted with restoration of many
early model vehicle components, traditionally
nickel plated.
Electroless Nickel
  • Electroless Nickel is a chemical plating process
    which, unlike electroplating, does not require
    electrical current to deposit. Nickel is
    deposited to the surface metal via an
    'autocatalytic' process which deposits the
    coating in uniform density to the surface being
  • The Electro-less Nickel plating process has many
    advantages over 'electrolytic' processes in an
    engineering environment. The coating can be used
    where a hard, corrosion resistant finish is
  • A major advantage of the process is that it is
    possible to coat the whole surface of an item
    EVENLY, including internals, unlike electrolytic
    processes which have difficulty depositing into
    recessed and internal areas and can result in
    excessive build-ups on points, corners, etc.

Applications of Electroless Nickel Plating
Valves, shafts, drilling equipment, rollers,
dies moulds, tooling, pumps, hardware more.
Wherever there is need to prevent corrosion,
reduce wear or improve hardness and durability.
Plating grade plastic
  • Decorative plating on plastic is achieved by a
    metallising process specifically engineered to
    enable non-conductive ABS plating grade plastic
    to be electroplated.
  • Why ABS Plastic? ABS is a specially designed
    plastic (Acrylonitrile Butadiene Styrene) with
    properties suited to the metallising process
    enabling continuous production of high volume
  • Benefits of Plating on ABS Plastic Substrates
    Moulded ABS plastic components are substantially
    cheaper to manufacture than metal parts. They
    offer adequate strength and significant weight
    reduction is also a benefit in some instances.
    After plating there is no apparent difference
    visually between metal and plastic parts.

Applications of Plating on ABS Plastic
Substrates Automotive decals and trim, tap-
ware, furniture trim, bathroom accessories,
hardware accessories, some electrical fittings
and many other items.
Zinc plating
  • Zinc plating is the most common, low cost
    electroplated coating that is normally applied to
    ferrous components to give corrosion protection.
    The coating can be coloured to give gold black
    or olive drab coatings by post treatment. The
    relatively low cost, protective nature and
    attractive appearance of zinc make it a popular
    coating for nuts, bolts, washers, metal stampings
    and automotive parts, such as interior components
    and gas filters. In addition, zinc serves as an
    effective undercoat for paints when high
    corrosion performance is required.What Material
    Can Be Zinc Plated? Near any metal can be zinc
    plated but the most common are steel and iron on
    which it offers sacrificial protection.

Recommended uses for Zinc electroplating Zinc
plating is used where a clean, smooth, corrosion
resistant surface is required. Commonly used on
nuts, bolts, metal brackets. etc but it also
makes an excellent undercoat for powdercoating or
paint. Zinc electroplating can leave recesses on
complex shaped components without sufficient zinc
coating to provide corrosion protection. Finished
Products can recommend other coatings that may
overcome this effect.
Hot Dipped Galvanising
  • Heavy galvanizing is often referred to as batch,
    heavy duty or after fabrication galvanizing.
  • Light galvanizing is referred to as continuous,
    ILG (In-Line Galvanizing) or zinc electroplated.
  • The Australian market has a wide variety of local
    and imported light galvanized products readily
    available. (See previous slide)
  • Heavy galvanizing is the only galvanize finish
    that gives a complete coating of heavy zinc both
    externally and internally.
  • The zinc coating is typically in the range of 85µ
    m² or 600 gms / m² on 6mm thick steel.
  • Heavy galvanizing produces the maximum thickness
    possible relative to steel thickness, with long
    term protection its only objective.

  • Roof sheeting made from ZINCALUME steel is
    available in a range of profiles.
  • The zinc/aluminium alloy coating on ZINCALUME
  • imparts corrosion resistance of up to four times
    the life of galvanised steel.

Colorbond Steel
  • Colorbond is the name given to a special grade of
    corrosion resistant high strength steel that is
    coated with zincalume and painted in a limited
    range of colorbond colours. The special corrosion
    resistant base metal means that any exposed
    edges/surfaces (due to cuts and scratches) do not
    cause premature corrosion failure.

  • Zincalume is for Factories Clients thinking of
    the option of using zincalume steel instead of
    Colorbond - thinking that there would be good
  • Colorbond is approximately 1.40 per square metre
    more than zincalume. But over the area of an
    average 120 square metre roof, it works out to be
    ONLY 168.00! ...And for this small sum, they
    will get a far superior product - and with a
    choice of colours too!
  • Zincalume is really the choice for factories
    which have roofs measuring many hundreds and
    thousands of square metres. And the price savings
    of using the cheaper material can be substantial