1.5 The uses of finishes Flashcards
Laminating
When paper is thread through a desk top laminator and heat sealed, leaving a polymer (PET and EVA) sheet over with a boarder around the edge (encapsulation). Can also be applied through a liquid with a roller or spray or film laminating made of PP with an adhesive.
Embossing
Raised design on surface of paper or cards. Used for greeting and invitation cards as well as packaging. Uses a male and female die made from stainless steel. Substitute is placed under pressure. An embossed area can have ink or foil applied, without any of these its called a blind emboss.
Debossing
Opposite of embossing and produces an imprint of the paper or card,
Foil Blocking
Application of heat and pressure to a metallic paper (oil) to create areas of depth and texture. Uses a heated die in which the design is stamped onto he material through the foil. Heat allows the foil to stick. If too much heat or pressure is applied the foil will bubble. Too little heat and the foil wont stick to the substrate
Varnishing
Clear, non-pigmented ink used on pre-coated papers to enhance colour. some offer protection against dit,fingerprints and water. Only suitable for ore-coated papers as these will not soak up the ink.
Spot Varnishing
Varnish applied in specific areas through plates. Used with varnish and UV varnish
Screen Printing
Used for posters, display boards and t-shirts.Image to be printed is created o a screen made of mesh held by a frame. a different screen is needed for a different colour. The substrate is placed over the machine bed and the screen is placed on top. Ink is forced through the mesh through a squeegee.
Flexographic Printing
Uses flexible printing plates wrapped around rotating cylinders on a web press. Water based ink is transferred to the plate cylinder by anilox roller and onto the impression cylinder to the plate cylinder
Offset Lithography Printing
Oil and water don’t mix. Plates are treated to be hydrophillic. The substrate is sheet fed onto the printing machinery. Printing placed produced by a computer by a laser. Ink is applied to the printing plate that printing onto a blanket roller.
Digital Printing
Used in flyers and business cards, ideal for mass customising such as printing specific names on drinks cans due to fast drying inks. The ink sits on top of the paper. Looks similar to large photocopies with great speed and efficiency.
Adding colour to the moulding process
Polymers are considered to be self-finishing as they require no additional finishing process once manufactured. Surface textures produced from mould.
Polymer Dip Coating
Used on wire coat hangers, dishwasher racks. Metal is heated to 230C and then dipped into a tank of fine polymer powder which has hot air (fluidisation bath). Which provides an even coating on the product. THe polymer powder melts.
Metal Dip Coating
Same as polymer dip coating but for metal. Typically used for low carbon steel protecting it from rust. The molten material is called the donor material. Tin is plated at 320C to prevent food cans from corroding. Zinc platings or galvanising is done at 460C used for beams gates and animal pens.
Powder coating
Product is statically charged (negatively). Thermoset polymer is positively charged. The charge attracts the power to the product. The product is heated in the oven to give even spread. Much more hardwearing than paint. Used in machine bodies, dishwashers and refrigerators and applying colour to metal gates and fencing.
Water Based Paints
Apply with a brush, roller or spray.
Wood knots should be treated with knotting and undercoat applied before application.
Provides protection
Stains
Used to help colour and enhance the grain. Stains are water-based and can be used to colour an inexpensive wood make it look like a more expensive timber or merely to add colour while allowing the grain to show but no protective properties.
Wax
Buffed to provide a high gloss finish.
Increases surface hardness and toughness.
The clear finish allows the grain of the wood to be seet through the finish.
Pressure Treating
Helps protect the wood for up to 50 years from tot, insect fungal attack and weathering. Used in decking.
Yacht Varnish
USed in woods that are outside all year round such as doors, window frames or boat parts. Increases toughness hardness and weather resistance.
Danish Oil
Enhances the grain. Used in outside furniture but must be regularly applied and subsequent coats build up a matt, water-resistant finish.
Teak Oil
Used in outdoor work wood products to improve weather resistance and resistance to fungal and insect attack. Applied with a lint-free cloth, rub the oil into the grain and leave to absorb for 5 minutes.
Substrate
The material on to which the print ink is applied such as paper or boards.
Electroplating
Cheaper metal coated with a more expensive metal creating an aesthetic appeal and barrier to corrosion from the contained liquid. Silver, gold, zinc, copper and tin are the anodes and the object to be plated is a cathode.
Anodising
The finishing process for aluminium products which enhances the natural oxide layer. Increases hardness and toughness. Used in torches, extenal hard drive covers and casings for mobile phones.
self finished
a material that has an acceptable finish after processing
self coloured
a material that has an acceptable colour after processing
applied finish
a substance applied to the material after processing
What is lamination used for
Paper, liquid lamination used for signage (protect from uv light or dust). Film lamination used for menu and business cards.
how can an accurate and non-blurry print be ensured?
The colours (CMYK) must line up precisely with each other. A registration system is used to ensure the final image is consistent. Used as QC to check all four colours have been printed in the correct place. seen on side of newspapers.
Advantages of flexographic printing
- High print speed
- ideally suited for long runs, wide variety of substrate materials
- low cost of equipment
- low maintenance
Advantages of offset lithographic printing
- high quality, consistent image
- suited to high volume production.
- long life as they only come into contact with printing blanket.
Disadvantages of offset lithographic printing
- expensive setup and running cost for small quantities
Metal Varnishing
The method that provides a clear finish to protect the metal and allow the colour of the base metal to show through. It is used on more expensive metals such as aluminium and brass. Then it should be polished to a shine and any surface grease removed.
Metal Sealants
Tough polymer based sealant coatings that protect polished surfaces from decay and tarnishing. Applied with a cloth or machine pad to produce a film that is allowed to cure for up to 15 minutes and subsequently buffed with a cloth to a shine. Used for automotive bodywork, freshly polished exhaust pipes and metal trims.
Cathodic protection
Method used to control the rate of protection by making the metal the cathode of an electrochemical cell. The anode of the electrochemical cell is a sacrificial metal which is more easily corroded. The anode corrodes while the base metal is protected. Used to protect steel structures immersed in water, such as pipelines.
Impressed current cathodic protection
The component to be protected connected to an electrical power supply. The impressed direct current flows from an inert electrode through any liquid to the component to be protected
Sacrificial Anodes cathodic protection
More basic method because it uses a sacrificial metal to protect the metal product of value a more electrochemically active metal is wrapped around the active metal to provide resistance to corrosion.
Adding colour in moulding
The pigment granules can be added to hoppers in injection moulding and the lay up process.
Acrylic Spray Paints and why is it better than pigments in mass customisation
A fast drying, water soluble paint used on polymers to proved improved aesthetics and additional protection against UV light and weathering. It would be impractical for the manufacturer to keep changing the granules to produce small numbers of different coloured materials
Overmouldings
A second polymer over specific parts of a product TPE is often used. Used to provide areas of grip and texture, or to highlight different colours for different components. A key example is a toothbrush. Applied either by using two injection moulds or twin shot injection moulding this process designed to produce the product in one cycle. The mould has two separate cavities to and can be rotated 180 degrees.
