Production of Wood pulp
- The fibres in wood held together by lignin must be separated, softwoods have longer fibres (stronger), hardwoods have shorter fibres (smoother finish). Three ways to produce pulp:
- Mechanical Pulp- logs coniferous trees saturated with water and de-barked, then ground down to soften lignin, and made to groundwood pulp. This is screened to accept 1-2mm pieces, larger parts are re-circulated. Can be used for low grade paper, so bleached with peroxide or sodium hydroxide. Most widely used method in UK.
- 90% yield as whole log used but the bark, investment costs are relatively low, bleached for higher quality, suited to bulk grades e.g. newsprint.
- Lower strenght characteristics than softwood chemical pulps, paper can yellow due to high lignin content in bright lights.
- Chemical Pulp- de-bark logs and cut to 2cm chips along grain, pounded to fragments and screened. Pulp stored and treated with acid/alkali to break down lignin. Most made using sulphate process.
- Higher quality with longer stronger fibres with few impurities, waste lignin can be burnt as a fuel oil substitiute to suppy power.
- Lower yield as lignin completely dissolved and separated from fibres, not produced in UK so must be imported.
Production of Wood pulp
- Waste pulp: recycled paper and board used for pulp often lower grades of paper, often mixed with virgin pulp to produce better quality paper, as fibres become shorter and weaker and loose quality for papermaking.
- Sustainable as makes use of recycled papers, well suited to bulk paper grade.
- Cannot recycle indefinitely as pulp loose quality, does not save energy in processing, requires considerable processing for good quality paper.
- Manufacturers blend variety pulps and process with bonding agents/pigmnets to produce different qualities.
- Help achieve consistent colour/binding of fibres for a better surface finish.
- Sizing agent can be added to improve water resistance, to prevent ink from bleeding or feathering on surface.
- Wet End: wood pulp diluted to 99% water, to form slurry held in head box. A continous stream is pumped through a slit (the slice) onto moving gauze wire belt to drain water and allow fibres to interweave. Watermarks can be added with raised gauze.
- Press Section: uses a system of rollers that wring out majority of excess water, and stretches pulp to rough paper. The gap between press rollers is adjusted to allow differing thicknesses.
- Dryer Section: dries paper using steam-heated rollers to remove moisture (like ironing clothes), til the water content os 4-6%. Sizing agents, starches and resins are added here.
- Calendar Section: series of rollers that the paper is fed in order to smooth it out for uniform thickness. The pressure applied determines the finish of the paper.
- The paper is wound onto webs and stored. It can be cut to size or shipped to a printer for web-fed printing.
Properties of Paper and Board
The choice of paper for an application is often decided by:
- the design requirement of the client
- the demands of the printing process/surface decoration
- economic considerations
Weight and Size
- Weight of paper is defined as gsm- grams per square metre
- Card and board are measured in microns/micrometres
- Paper is usually classified as board after 220gsm
- The thickness of card/board can be measured in ply
- 2 ply = 200 microns, 3 ply = 230 microns, 4 ply = 280 microns, 6 ply = 360 microns
- Paper, card, board are most commonly measured in A sizes, but B sizes are also used (old imperial measurments)
Properties of Paper and Board
Common Drawing Papers
- Layout Paper- 50gsm, thin translucent paper with smooth surface, used for sketching and developing ideas and marker renderings. Allows tracing through to another sheet, accepts most drawing media, relatively expensive.
- Tracing Paper- 60-90gsm, thin transparent paper with smooth surface, pale grey apperance, same uses as layout paper, preferred by draughtsmen, allows tracing through to develop ideas, heavier weight can be expensive.
- Copier Paper- 80gsm, lightweight quality paper, good bleached surface, used for print/photocopy from inkjet/laser printers, general use for sketching/writing. Bright white and available in different colours, inexpensive when purchased in bulk.
- Cartridge Paper- 120-150gsm, creamy-white with smooth surface, slight texture, good general drawing paper, heavier weights accept paints. Completely opaque, more expensive than copier.
Properties of Paper and Board
Commerical Printing Papers:
- Bond paper- 50gsm+, high-quality, durable writing paper often with watermark, name from original use in government bonds, used letterheads/stationery and paper for electronic printers, widely used for pen, pencil, felt-tip work. Largely made from rag pulp, stronger than wood and long wearing, available in many colours, inexpensive when purchased in bulk.
- Coated paper- 70-300gsm, covered with suspension of china, clay, pigment and adhesive for smooth surface finish, used wide range high quality printing, the coating fills minute pits between fibres, range of finishes available from gloss, matt, satin, silk, relatively expensive.
Commercial Card and Board:
- Recycled card- 220gsm+, made from % of waste pulp, used in environmentally friendly products, disposable items and inner packaging, lower quality than made from virgin pulps, flecked appearance quality of its own, can be coloured for visual effect, inexpensive.
- Mounting board- 1000-1500 microns, thick board with colour on one side, used mounting work for presentations/displays, very high quality, strong rigid board, avaliable in range of colours, expensive.
Properties of Paper and Board
Used extensively in retail packaging, must be suitable for high quality, high speed printing, and cutting, creasing and gluing. Advantages include graphic coverage and excellent print quality, protection in structural packaging nets.
- Folding boxboard- Usually bleached virgin pulp top surface, unbleached middle and bleached inside layer, widely used for food packaging, excellent for scoring, bending and creasing without splitting, good printing surface, relatively inexpensive.
- Corrugated board- fluted paper layer between two paper liners, used protective packaging for fragile goods, most commonly used in boxes, excellent impact resistance and strenght to weight, low cost, recyclable, relatively inexpensive.
- Solid white board- entirely from pure bleached wood pulp, used packaging for frozen foods, pharmaceuticals, very strong and rigid, excellent printing surface, expensive.
- Foil-lined board- laminated foil coating (can be used on all above), foil in matt, gloss, gold, silver, used in cosmetic cartons, pre-packed food, very strong visual impact, foil provides moisture barrier, expensive.
Ferrous Metals- contain mainly iron, also includes small additions of other substances, almost all are magnetic.
Non-Ferrous Metals- contain no iron, are not magnetic.
Alloys- formed by mixing 2+ metals and sometimes other elements to produce metals with enhanced properties.
Metals are commonly used in commercial packaging, there are many advantages:
- added security- sealed cans cannot be changed without obvious signs
- containers can be made in a variety of standard sizes e.g. drinks cans
- Metals can be directly printed on or have paper label for total graphic coverage, effective point of sale displays created
- Strong but lightweight, easily moulded, and does not rust.
- Pure metal, naturally occuring and mined from beneath land/sea, from ore bauxite.
- Alumina is extracted from bauxite, then electrolysed to form aluminium metal, uses lot energy.
- Easily recycled, and does not loose its quality, also saves energy and is sustainable.
- From cassiterite (tin oxide), smelted by reduction with carbon, in a reverberatory furnace.
- Ability to mix with majority other metals, also low melt point make essential ingredient in solder.
- Non-toxic and does not corrode rapidly making it ideal protection for steel in food cans.
- Usually in form of tinplate, cold rolled steel with thin layer of tin, lightweight and easily moulded.
- Produced from iron ore, lot energy to convert to steel, has to heat in furnace to high temperature, however easily recycled in 75% less energy than extraction from iron ore.
- It is magnetic making it easy to sort using electromagnets at recycling plants to separate steel.
- Stainless steel- 87% carbon steel for strenght/rigidity, 13% chromium for resistance to wear/corrosion. Over 150 grades available, (increase chromium content), used in cutlery, jewellery, cookware, building construction etc.
- excellent resistance corrosion, rust and staining, high quality surface finish, low maintenance, 100% recyclable.
- Relatively expensive, relatively hard to machine.
- Duralumin- 93.5% aluminium for strength/lightness, 4.4% copper for strength, 1.5% magnesium as alloying agent, 0.6% manganese to remove oxygen. Applications make use of strength:weight ratio, aircraft/vehicle structures, precision tools/components, bicycle parts etc.
- excellent strength:weight ratio, extremely hard/tough, high resistance to corrosion cracking, machines/casts well, high peformance in extreme temperatures.
- Can suffer from corrosion, becomes brittle through fatigue.
Polymers in commercial packaging
- thermoplastics often used in packaging- once heated can be formed into many shapes, permanently, but once heated they can be remoulded (easy to recycle)
- Advantages include: lightweight/versatile, strong/durable, impact/water resistant, easily formed/moulded, easily printed on, inexpensive, recyclable.
- Polymers used can be identified with international recognised symbol on label or base of package to sort prior recycling.
Styrofoam in modelling
- Styrofoam is blue/pink extruded polystyrene foam used for insulating buildings, but also useful for block modelling.
- Process of making it results in uniformly small, closed cells which gives great rigidity, high compressive strength, easy to cut/shape with normal hand tools, sand for a smooth finish.
- Also available in a range of thicknesses, and can be glued with PVA to create larger blocks and painted with acrylic for good quality finish.
- Higher quality can be finished by coating with layers of plaster, sanding smooth then using spray paints.
- There are some disadvantages, it is weak, surface breaks easily so is unsuitable for fine detail, the surface can be dinted when using a file or ripped by sand paper.
- PET- used carbonated drinks bottles, packaging highly flavoured food, microwave food trays
- Excellent barrier atmospheric gases, not flavour contents, crystal clear look, tough, light.
- HDPE- used unbreakable bottles (detergents etc.), very thin packaging sheets.
- highly resistant to chemicals, good barrier to water, tough/hardwearing, decorative when coloured, lighweight, floats on water, rigid.
- PVC- used for packaging toiletries, pharmaceutical products, food/juice confectionery.
- weather resistant/ does not rot, chemical resistant, protects products moisture gases, hold in preserving gases, strong, good abrasive resistance/tough, manufactured flexible/rigid.
- LDPE- used stretch wrapping (cling film), milk carton coatings.
- chemical resistant, barrier water not gases, tough/hard wearing, decorative when coloured, light floats on water, flexible.
- PP- used food packaging, yoghurt/margarine pots, sweet and snack wrappers, used laminating board/paper.
- lightweight, rigid, chemical resistance, versatile, low moisture absorption, impact resistance.
- PS- (rigid) used food packaging, CD cases, audio casette cases, transparent, rigid, lightweight, low water absorption.
- (expanded) use egg cartons, meat trays, cups, impact resistant, heat insulator, durable, light
- Common name for PMMA, tradenames include Plexiglas and Perspex.
- Usually cast into sheets also available in rods and tubes and is self finishing.
- Wide range of applications, point-of-sale displays to shop signage.
- Architectural grade acrylic has to meet several high peformance requirements in shop signage.
- Withstand extreme weather conditions, chemical resistant, durable by resisting long term stresses, easy to fabricate and have excellent aesthetic properties.
- Clear/frosted acrylic often used point-of-sale displays and illuminated signage as low-cost/lightweight substitute to glass.
- Main disadvantages, brittleness and low scratch resistance, cracks easily form and spread through acrylic, and can snap easily so great care must be taken.
- Main disadvantage widespread use is sustainability, made from oil which is finite, also consumes lot energy in production process, and produces pollution.
- Also problem of disposal, polymers are durable and degrade slowly, which is a problem in landfil sites.
- Incineration is also not possible, as burning polymers can release toxic fumes.
- Recycling could solve the problem, thermoplastics can be moulded into new products, but collection and sorting is also an issue.
- Can be sorted/identified, by means of ID code, but slow and labour intensive process.
- Mechanical methods of sorting available but not widespread, also contamination problem, majority e.g. bottles made of one polymer, closure made of another.
- Recycling some types of polymers is also unprofitable, e.g. polystyrene rarely recycled as usually not cost effective.
- Hardwoods- Produced from broad-leaved trees with enclosed seeds e.g. oak, mahogany, beech, ash, elm.
- Commonly grow in warmer climates e.g. Africa/South America, take 100 years reach maturity.
- Usually tough/strong with decorative finish due to close grain.
- Many expensive due to location and age, may only use for high quality.
- Exception balsa wood, used for modelling applications many years, inexpensive/easy shape.
- Jelutong- from Indonesia, low density, straight grain, fine texture.
- Balsa- from South America, extremely buoyant, very soft/light, low density with high strength.
- Softwoods- Produced from cone-bearing conifers needle-like leaves, e.g. Scots pine
- Grow more quickly (30 years), be forested/replanted, in abundance therefore cheaper.
- Generally are easier to work with, lightweight so more suitable for modelling.
- Contain grain, harder to shape block modelling, so MDF more applicable.
- Scots pine- from Northern Europe, easy to work, knotty, prone to warping.
- Parana pine- from South America,vstraight grain (knot free), strong/durable, smooth finish.
- Whitewood- from Northern Europe, South America, strong not durable, easy work, very resistant to splitting.
Composites- when two or more materials are combined by bonding, has improved mechanical, functional and aesthetic properties, and excellent strenght to weight ratio.
- Glass-reinforced plastics- made of epoxy resin reinforced by fine fibres of glass in form of woven matting, plastic for compressive strength, glass for tensile strength.
- Resin in liquid form, has catalyst/hardener added become solid, glass provide basic structure, resin with additives bonds fibres together.
- Can be used uniformly or specifically placed, made smooth by high polished mould, and careful application known as gel coat, one side high polish, other side rough.
- Used canoes, fairground rides, vehicle bodies, fish ponds.
- Excellent strength:weight ratio, resistant corrosion, water resistant, wide range colours/pigments added to resin, be repaired easily.
- Expensive material, specialised manufacturing process, high-quality mould needed.
- Carbon fibre- more recently commercially developed similar form to glass fibre, made of carbon fibres, for tensile loads in polymer resin matrix, for compressive loads.
- Filament material, incorporates thousands filaments woven in different directions to form fabric, covers tensile loads in all directions.
- Much stronger than GRP, ideal for high performance structures and sports equipment.
- Have unrivalled mechanical properties, easily out-perform metal alternative, e.g. has 4x more the tensile strength than best steel alloys, at 1/4 weight.
- Used in sports equipement e.g. tennis raquets, fishing rods, bicycle frames and wheels.
- Can be engineered anisotropic (fabric different directions), be formed into one-piece aerodynamic structures.
- Very expensive material, only available in black, highly specialised manufacturing, cannot be easily repaired/recycled.
- Medium-density fibreboard- made wood chips subjected to heat/pressure, make fluffy/soft pulp, mixed with synthetic resin adhesive bond fibres for uniform structure, heat pressed.
- Used flat-pack furniture, general joinery work, moulds for forming processes etc.
- Less expensive than natural timber, available large sheets, no grain, consistent strength.
- Heavy, require finishes to seal, swells when waterlogged, warps if not sealed, irritate eyes.
Modern Materials and Products
- Liquid Crystal Displays
- Organic carbon based compounds, when has voltage applied and light falls it appears dark, caused by rearrangement of molecules.
- In digital clock, an LCD display, has pattern of electrodes to display digits with 7 segments.
- Very small amount of current is needed, ideal portable electronic devices.
- Now have full-colour LCD screens e.g. laptops, each pixel has 3 sub-pixels in red, green, blue filters, vary voltage, each sub-pixel produce 256 colours.
- Phosphorescent pigments
- Absorb energy during day and release slowly at night, non radioactive like old forms.
- Can be manufactured into polymers used in paints/inks to make safety signage, watch faces that glow in the dark.
- Electroluminescent lighting (EL)
- Convert electrical energy to light, by applying voltage across electrodes, orgainc phosphor put between two conductors, to rapidly charge and emit radiation in form of light.
- Exremely low power consumption, used backlight for LCD displays, or advertising.
- Produced paper thin wires, strips, panels, applied to designs able to use in bus shelters, sides of buses, billboards as waterproof, high visibility, reliable.
- Change to differences in the environment, some revert back to original state, have "memory"
- Thermochromic liquid crystals- used forehead thermometers etc.
- Layer conductive ink printed on reverse, with layer with temperature gauge on top in normal ink, on top of this is thermochromic layer, black when cool. Temperature make ink translucent to reveal temperature gauge underneath.
- Other printing inks available promotional use, e.g. thermoreactive inks reveal graphics if hand placed on, or if put in fridge, some inks react to UV light- photochromic inks.
- Piezoelectric crystals- expands/contracts when electrical current applied, convert mechanical stress/vibration to electrical signals, vice versa, e.g. some inkjet printers have one fitted back reservoir each ink nozzle. Crystal recieve charge cause vibrate inwards, force ink out, vibrate out, pull ink to reservoir. Act as actuators or transducers.
- Actuator- control mechanism/system, e.g. musical greetings card, music activate when insulating tongue removed from contacts, crystal act as speaker driver allowing generate pre-programmed sound stored on integrated circuit mounted on module.
- Transducer- converts electrical signal from one form to another, e.g. electronic drum kit, when drum pad struck, voltage change triggered in crystal, resultant signals translated digital waveforms, produce desired percussion sound.
- Smart Ink- designed mimic apperance ordinary ink on paper, electronic paper desgined to overcome limitations computer screens e.g. backlight hard on eyes, whereas electronic paper reflect light like normal paper etc.
- Used in more expensive e-readers, kindle etc., advantage is pixels have stable memory effect, so don't need power to maintain images, only draw on power when page refreshed.
- Each pixel is a tiny point with black/white beads, white positive charge, black negative charge.
- Each point is topped with a transparent electrode, has has two electrodes at the base, altering the charge in the base makes the white/black beads rise to be displayed, making one positive and one negative on the base creates a grey spot.
- Radio frequency identification (RFID)- method identification, uses tags on products to store data retrieved by a reader, often used to track pallets of production, library books etc.
- Based on transmission/reception radio frequency between transmitter/transponder, most cases is two way, available in active/passive forms.
- Active transponders- battery powered, read great range, expensive used vehicles (road toll payment), shipping containers, have limited lifetime.
- Passive transponders- power need from electromagnetic signals transmitted, strength fall quickly, used need thin, convert to label, pallet tracking/library.
- Saddle-wire stitching- simplest method, staple pages through fold, use brochures, comics.
- Ideal signature feed process (folded pages), printed material laid flat to read, inexpensive.
- Lower-quality visual apperance, not durable as centre pages easily fall apart.
- Side-wire stitching- Staples through side close to spine, used photocopiers to collate/staple documents, e.g. revision materials, booklets etc.
- Used when too thick for saddle-wire, inexpensive, ideal binding single sheets without folds.
- Cannot lay material flat as cause damage to spine, lowwer quality visual apperance.
- Spiral and comb binding- pages punched series holes along spine, spiral steel/plastic band inserted through holes to hold together, used business reports/documents.
- Inexpensive, ideal binding single sheets without folds, good quality visually, lay material flat.
- Not durable as can easily fall apart or tear down perforations.
- Perfect binding- pages held/fixed by cover with flexible adhesive, use paperback books etc
- Better visually/quality, pages together to roughen/flatten edges, provide longevity with glue.
- Expensive commercial process.
- Hard-bound or case-bound- combine sewing and gluing for most durable binding method, used hardback books etc.
- Stiff board protect/cover pages, high quality/professional, extremely durable
- Very expensive commercial process.
Scale of Production
- One-off- include bespoke/customised solutions, high-cost to customer specification, used prototype models, shop signage, vinyl stickers etc.
- Made exact personal specifications, high quality materials, high skilled craftsperson.
- Expensive final product in comparison, labour intensive and can be time-consuming.
- Batch- manufacture identical products, from 10s-1000s, has fast turnaround to manufacture different product, make use flexible manufacturing systems (FMS) and computer integrated machinery (CIM), to minimise down-time of production, used magazines, newspapers etc.
- Easy to adapt to another product, fast response market trends, identical, lower unit costs.
- Poor production plan result large amounts storage costs, frequent tool change costly.
- Mass- use efficient automated manufacturing process, low-skilled workforce, follow market trends also, used electronic products e.g. phones, commercial packaging etc.
- highly automated, rigorous quality control, low unit costs, set-up costs quickly covered.
- job dissatisfaction- lowpaid, repetitive, ethical concerns with sweat shops, not change market trends quickly, high intitinal set up costs due to machinery.
- Continuous- manufacture standardised goods meet everyday mass-market demand, used cans/bottles for drinks
- (same as mass production), extreme low unit costs, runs 24/7
- (same as mass production), little flexibility as production is 24/7
- Visual representation information, pictorial drawings used visualise/represent objects in 3D include exploded/assembly drawings, working drawings in 2D so easily read/interpreted/make.
- Isometric- accurate show 3 faces, lines true/scaled, vertical at 90, horizontal at 30, circles distorted, used sketchin design ideas, illustrate product designs.
- 2-point persective- draw as human eye view, parallel lines converge at vanishing points, worms eye, above horizon line, street level, on horizon line, bird's eye below horizon line, used illustrate product designs, architecture, interior designs.
- Planometric- also axonometric, used interiors as allow bird's eye view, drawn 45/45 or 30/60 horizontal, all dimensions true scale, vertical lines can reduce by 3/4 to 1/3 to avoid distortion, circles/curves drawn as appear in view (compass/circle template) used architectural drawings.
- 3rd angle orthographic- represent 3D in 2D with multiple views, front elevation, end elevatoin, plan (bird's eye), hidden detail shown dotted lines, dimensions in mm, centre lines, 3rd angle symbol- British Standards Institute (BSI) standards, used engineering drawings.
- Nets- also development, flat 2D shape cut, scored, folded make 3D shape, include cut lines, fold lines, tabs, closure system, used structural packaging design.
- interpretation of one method of drawing of an object into another
- Translate from working to pictorial drawings- e.g. 3rd angle orthographic to 2-point perspective of same object.
- Translate pictorial to working drawings- e.g. isometric to 3rd angle orthographic projection.
- Translate pictorial drawing to nets- e.g. isometric of packagin, draw what ned would look like in order to construct package.
- Translate from net to pictorial drawing- e.g. 2D net to isometric of packaging.
Computer Generated Graphics
- Use of computers for design of printed materials/products now standard over manual drawing, possibilities led to rapid development.
- One of main drawbacks is training required to use complex software systems and costs.
- Desktop Publishing (DTP)
- Combine word processing, graphic design and printing in one package, modern print media use to produce layout of pages rather than typesetting, features include, import of text/graphics, create illustrations, predetermined grid layout, proof copy print in colour first.
- text/image manipulation, graphic tools available, add page layout/grid guides, cut/paste
- Need regularly invest new software/hardware and re-training, incompatibility of files/systems.
- 2D computer graphics
- This and digital illustrations rapid growth, many drawings hand drawn/rendered easily achieve with 2D software packages offer tools manipulate images.
- Basic tools allow lines/shapes drawn, add colour and texture to, have effects and filters to vary the look e.g. blur or mosaic.
- Digitised images e.g. scanned/existing pictures can be combined/manipulated same way.
- Many contemporary characters designed for T-shirts, album covers, illustrations etc, constructed basic geometric shapes layered on top of each other with different colour filters.
Modelling and prototyping
- Sketch modelling- Help determine shape, dimensions, surface details by constructing 3D representation of concept product usually out of foam.
- Useful for ergonomics, construct models varying shapes/sizes, become apparent which designs user friendly/aesthetically pleasing, and worth developing, hard to achieve in 2D drawings.
- Stereolithography- Use laser to solidify resin, 2D CAD drawings converted to 3D models, computer slice into thin layers and transfer data to the laser. Works with vat of liquid resin and moving table (platform).
- Platform start at top, laser draw on resin to solidify on platform, platform moves down so more resin covers the solid layer, that is solidified also, continues until shape formed. Once finished, platform rises so model emerge from the liquid resin.
- Usually companies send to RTP sevices, have prototype 3-5 days, save time and cost.
- Drawback is cost, machine cost £10,000, cost of resin also and software.
- Also selective laser sintering (SLS), high power laser fuse particles of material into mass to form 3D product, fuses by scanning cross-sections generated from 3D pattern, after each layer, table moved down until part completed.
- Virtual modelling- Design product in 3D, virtually, test and evaluate without even manufacturing product, animation start with wire frames, viewed all directions with cameras, then render to look real.These models can be used to give walkthrough of interior designs.
Modelling and prototyping
- Wire frame model- visual representation of 3D object created by collection straight lines, curves, intersections, result transparent skeleton of drawing, with impression of 3D structure.
- Simple/fast calculate, used where high screen frame-rate needed, review changes/rotate objects, well suited to computer numerically controlled (CNC) programming.
- difficult to read/interpret as hidden lines also in view, lack of detail.
- Surface model- surface/skin added to wire frame, make more realistic picture of 3D object.
- Greater definition contours/surfaces, blending between surfaces improved, hidden lines be removed to give more solid feel.
- Does not give information about surface textures/finishes.
- Solid model- production of full digital representation of object with properties of solid form.
- Photorealistic image produced with rendering to apply shade, surface pattern and texture, clear communications, no confusion.
- Complex data required, slow to update an render objects.
- Contact adhesive- used unlike materials e.g. plastic to wood, general use most materials.
- bond unlike materials, form quickly no need to clamp, idea glue large sheets, sold metal tubes.
- must apply to both surfaces, leave before push together, expensive, solvent based, VOCs
- Acrylic cement- used for acrylic, rapid bonding for acrylic.
- difficult to apply to give neat joint, expensie, solvent based so has volatile organic compounds.
- Polystyrene cement- used high impact polystyrene (not expanded)
- strong bond, melts surface of pieces joined weld together, apply with brush and absorbed to joint with capillary action.
- expensive, solvent based so has VOCs present.
- Epoxy resin- use most materials including expanded polystyrene.
- high peformance, high-strenght bond, chemical reaction harden immediately, versatile- make flexible/rigid, clear/opaque, rapid/slow setting, excellent heat/chemical resistance.
- reach full strength after few days, expensive, often require manual mixing resin/hardener which can be messy.
- Polyvinyl acetate (PVA)- used on woods/porous materials.
- gives a strong joint, inexpensive.
- surfaces need to be clamped together for PVA to harden, not waterproof (some brands are)
Industrial and Commercial Processes
- Structural packaging nets- flat 2D shape can be cut, scored, folded produce 3D shape, widespread in production packaging using cartonboards, package serve 4 main functions, contain, protect, dispense and adveritse. Many companies produce standard nets for designers to use and add own graphic to, save time/cost in developing.
- Designing and creating packaging nets- accuracy drawing important, CAD programs should offer this, produce accurately, final 3D shape need developed/drawn by hand/computer.
- Enable shape, size, layout of net drawn more accurately.
- Needs to include, cut lines (continuous), fold lines (broken), tabs, closure system, annotation.
- Commercial production- often require large-scale production processes involving automated machinery.
- Preparation- make die form for cutting and creasing process, pre-press (4 colour printing plates), purchase cartonboard, printing inks, adhesives.
- Processing/production- full colour printing to board, apply in-line surface finish, die-cut individual nets incorporate score fold lines.
- Assembly- folding of net into shape, glue tabs for 3D structure, product/internal packaging instered, final flap glued to position.
- Finishing- collation multiple units, pack corrugated boxes/sealing, multiple boxes palletised/shrink wrapped ready for distribution.
Industrial and Commercial Processes
- Process involve cutting/shaping hardened steel rules (press knives) and matrix strips, either cut/crease cartonboard on die-cutting machine, ejector rubbers added to rulers to push board away from rulers
- Making the die form- nets cut to shape after printing before assembly/gluing, cutters used are dies, stamping process is die-cutting. Make die-form using CAM operated forming machines, often skilled, hand crafted process.
- after cut been made, mounted on machine, major cost in process to make.
- Die Cutting- while die-form made, cartonboard selected and cut to size on power guillotine, then printed on, after die-form mounted on machine, test sheet cut and adjustments made then each printed sheet fed onto a platen, below die-form.
- Platen forced upwards, push board against rulers, cutting rules cut right through board, while creasing rules push card into groove formed by matrix strips, once cut sheets pulled to next stage to be stripped of waste, ejector pins on die-form push waste away to conveyor belt.
- Folding and gluing- mass production/large batch production, nets folded/glued on highly automated gluing line, first pre-fold one of creases, carton travel automatic gluing station.
- Gluing module timed by simple control system, front edge card black break light beam, triggers squirt glue quick succession, final fold made and edges held together under moving belt until reach final stage, stacked and compressed with pressure under slow moving rubber belt, adhesive time to cure before pack for transit, shipped to assemble/fill.
- Blow moulding- hollow thermoplastic tube (the parison) is extruded between a split mould and clamped at both ends, hot air is blown through parison, expands to take shape of mould, including relief details e.g. threads and surface decoration, once cool/solidify, ejected by opening mould. Don't have to be symmetrical, include handles screw threats etc.
- Intricate shapes formed, produce hollow shapes thin walls reduce weight/cost, low unit cost
- High initial set-up mould expensive to develop, HDPE, LDPE, PET, PP, PS, PVC.
- Injection moulding- high-cost mould, inject liquid polymer made thermoplastic granules, once polymer cools/solidifies, product ejected, suitable complex shapes with holes, screw fittings, integral hinges, formed thinning polymer.
- Ideal mass production, low unit cost, precision moulding, quality surface finish/texture mould
- High initial set-up costs as mould expensive to develop/produce, nylon, ABS, PS, HDPE, PP
- Vacuum forming- thermoplastic sheet clamped/heated then blown/stretched, air is sucked out of machine to pull softened sheet over mould pushed up from below, once cooled/solidified cold air blown between mould and plastic to release formed product, multi-moulds of 4,6,12 identical used for small batches in one forming.
- Ideal batch production, inexpensive, relatively easy to make moulds be modified.
- Mould need to be accurate prevent webbing, large amounts waste, Acrylic, HIPS, PVC.
- Provide wide range uses across whole spectrum printed products due to properties good gloss, strength and low cost.
- Encapsulation- similar to lamination addition heat seams, fully covering edges paper/board, commercial printers use roll laminators, large print runs e.g. menus restaurant chains.
- Smaller batches required, e.g ID cards, small inexpensive pouch laminator used, inside lamination pouch coated heat-activated film stick to paper passes through heater to activate, then pressure rollers ensure all bonds sealed.
- Varnishing- applied for high-gloss, fine varnish spray to surface, once dry help protect printing underneath, only take place after colour printing complete, due oil/water based varnished take 2hrs to dry, bad as other processes have to be delayed, UV varnishing can be used, dry almost instant under UV light. Sprayed on as usual, then pass under UV lights, allow printed material move on other pro
- Laminating- apply transparent plastic film to surface of paper/board, commercially use polypropylene (PP) film glued paper as fed through heating wedge under high pressure.
- cesses quicker, expensive machinery, produce ultimate gloss finish, also be applied screen printing process- applicable spot varnishing- apply UV to spots or flood page.
- UV sparkle varnish- metallic polyester flakes add sparkle
- Fragrant burst inks- scratch n sniff, fragrance locked in molecules, scratch release it
- Silver latex scratch offs- designed opaque inks print over tickets and scratch off.
- Hot foil blocking- used produce true reflective metal printing, other effects impossible normal metallic printing inks, use enhance/add value to printed materials, transfer foil coating to paper by means of heated die. Roll foil with polyester backing sheet continously fed over paper/board and heated die presses foil to surface.
- dry process, no fumes/solvent vapours, image 100% opaque, economic in short-run printing.
- image under heat/pressure, tends spread, difficult reproduce tints/halftones, fine line work printed satisfactorily, range colours limited produced foil manufactures, can match colours, many cases is nearest available wll have to be used.
- Embossing- Create 3D image/design in paper/board with raised effect, also use debossing, where image lowered into surface of paper/board, involve heated metal die (female) and counter die (male) that fit together under pressure and squeeze fibres of paper to shape.
- Pressure/heat irons while raising level of image higher than paper to make smooth, commercially carried out letterpress machine at end production after varnish/laminating, end result high quality and sophsisticated appearance, cost much as printing, double overall cost.
- Laser cutting and engraving- use high power laser cut materials, usual use industrial manufacture produce features problematic to die-cut. Eliminate need expensive toolying, laser direct control computer use CAD/CAM system.
- Laser melt/burn/vaporise material leave edge quality surface finish, ideal signage manufacture, laser enter side sheet cut through axis of beam, order cut somewhere other than edge, pierce made before every cut, with high power pulsed laser beam slowly make a hole.
- Used direct laser imaging- lithographic printing plates use CO2 laser imaging head burn away unwanted material form negative printing plate from digital data.
- Used direct laser engraving- flexographic/gravure printing plate/cylinders use CO2 laser head sharp relief image steep, smooth edges high standard process colour reproduction.
- lack physical contact material give clean edge, precision, reduced warping.
- very expensive machinery, high energy consumption require to power lasers.
- Vinyl cutting- ideal one-off/batch production, many schools access CAD/CAM to cut vinyl directly replicate commercial process. Image designed on computer, sent to cutter for contour cutting, commercial have image banks, accurate dimensions.
- background vinyl removed in weeding process, leave only requied graphic, adhesive used on rollers vinyl is contact adhesive, light coat on back, and cover treated paper make easy peel off. Then application tape added to remove from backing sheet, put on surface.
- Offset lithography- work basis oil and water not mix, development digital image setters enabled print shops produce negatives for plate making directly from computer images, using direct laser imaging, computer-to-plate (CTP).
- Printing plate made from aluminium/flexible polymer fixed to plate cylinder on printing press, rollers apply water covers blank portions of plate, repelled by emulsion of image area, ink applied by other rollers, repelled by water only adhere to emulsion of image area such as text/photos on newspaper page.
- If image directly onto paper, create positive image, but paper be too wet, so plate roll against blanket cylinder squeeze away water and picks up ink, paper roll across blanket cylinder and image transferred to paper.
- Involve multiple print units, each contain one printing plate for 4 colours, CMYK, capable printing multi-colour images 1 pass both sides of sheet high speeds, some can accomodate continuous rolls (web presses), to produce richer colours, can have more colours added.
- No particular order to print colours, printer make descision depending on nature of job and understanding of how produce best finish, good way seeing how separate colours used to create a range, magazine under tiny dots, process similar pointillism technique.
- good reproduction quality, inexpensive, wide range papers, widely available.
- colour variation, paper can stretch, set-up costs uneconomic short run, flat materials only.
- Flexography- uses relief-type printing plate with raised images, only raised images come contact with paper during printing, made flexible material, e.g. plastic, rubber or UV-sensitive polymer, they can be attached plate cylinder for ink application.
- Flexographic presses comprise plate cylinder, a metering cylinder known as anilox roll applies ink to plate, and an ink pan.
- Some presses use third roller as fountain roller, and some cases, doctor blade for improved ink distribution.
- Flexographic printing process, paper fed into press from a roll, image printed as paper pulled through series of print units, each print unit prints single process colour (CMYK), as with gravure, and lithographic, various tones/shading achieved by overlaying 4 basic shades inks.
- high speed printing process, fast drying inks, cant print on same presses as letterpress
- difficult reproduce fine detail, colour not consistent, set up costs high, rarely used print runs below 500,000
- used packaging, less expensive magazines, paperbacks, newspapers
- Screen printing- widely used commercial printing process, screen made porous fine material, strech over wooden/aluminium frame, stencil used block off areas of screen with non-permeable material, stencil is negative of image be printed so open spaces are where ink will appear, screens/stencils produced commercially using photo-emulsion technique.
- Screen placed top piece of dry paper, ink placed on top screen, squeegee (rubber blade), used puch ink evenly into screen openings and onto paper.
- Ink passes through open spaces in screen onto paper below, then screen lifted away, screen can be re-used after cleaning, more than one colour printed on same surface, ink allowed dry process repeated with another screen carrying different stencil and using different colour ink.
- stencils easy produce using photo-emulsion technique, versatile, print virtually any surface, economical short runs, fully automatic methods capable producing large volumes.
- Generally difficult to achieve fine detail, print requires long dying timess.
- Gravure- intaglio printing process, image engraved on copper plate cylinder, uses rotary printing press, vast majority presses print on reels of paper, rather than sheets.
- Fastest and widest presses used commercialy can print narrow labels to wide roles, in-line finishing operations e.g. saddle wire stitching also available.
- Has one printing press for each colour (CYMK), 5 basic components each unit, engraved plate cylinder, ink fountaion, doctor blade, impression cylinder, dryer, plate cylinder partial emersion in ink fountaion, fill recessed cells, cylinder rotate draw ink out of fountain.
- Acting as squeegee, doctor blade scrapes cylinder before contact with paper, remove ink from non-print areas, paper pass through impression cylinder and plate cylinder under pressure, ink transferred from recessed cells to paper.
- Purpose impression cylinder apply force, pressing paper onto plate cylinder, ensure even/maximum coverage of ink, then through dryer section as must be completely dry before next colour unit, and adsorbing another coat of ink.
- Consistent colour reproduction, high speed, widest print press, ink dries evaporation, variety in-line finishings available, good result low quality paper.
- high cost engraved printing plate/cylinder, efficient only long print runs, image print as dots, visible to eye, very expensive set up costs.
- Quality assurance
- QA systems are planned activities used by manufacturers to monitor quality of product from design/development stage, through manufacture to end use, and degree customer satisfaction.
- Ensure end product fulfils all of requirements for quality.
- QA ensure fit for purpose, use thorough testing of design/development stage
- Regulation quality raw materials/components manufacturer buys to start production.
- Monitor quality components, products, assemblies, in production through series quality control (QC) checsk, tests, inspections.
- Supply fact-based evidence for quality management systems, inspire external confidence to customers/stakeholders that product meets all needs and expectations.
- QC part of achievement of QA, involve actual activties used by manufacturer to ensure high quality product produced by means inspection/testing.
- Inspection- sampling/examination of components or products to check they are within specified tolerance (degree which component acceptable to function in accordance with its specification).
- 100% inspecton- all units
- Normal inspection- sampling plan under ordinary circumstances, e.g. large print rup 500,000 leaflets, check every 1000th colours against original check consistency.
- Reduced inspectoin- sampling plan require smaller sample sizes, used some as economy measure when level quality sufficiently good.
- Computer-aid inspection with coordinate-measuring machine (CMM), design move measuring probe determine coordinates of points on surface workpiece, quick, accurate measure size, laser scanning also used coordinate thousands points, can create 3D model.
- Testing- product performance, lab conditions, strict control procedures ensure accurate.
- Non-desctructive- test where product tested until show signs of failing, determine how much force needed to deform it.
- Testing to destruction- destroy product in controlled conditions, monitored to gather research data e.g. Euro New Car Assesment Programme (NCAP) for car safety testing.
Quality Control in Print runs
- Paper not inert, react to change in environment, may cause problems in print run, affect dramatically by temperature, humiditity cause to curl.
- Relative humidity of print room must be controlled, ensure curl stability, could affect colour registration of printed materials.
- Usually when paper arrive at print shop, kept storage to adapt to humidity of print room, during print run itself, make regular QC checks to ensure quality achieved.
- set off- ink from one sheet smudges to underside of the following, prevent with use sufficient anti-set off spray, sufficiently quick dry inks, or better quality paper stock.
- colour variation- printer not maintain consistent colour throughout run, prevent with use colour bars and regular densitometer readings.
- hickies- small areas unwanted solid colour surrounded by unprinted halo area, cause specks dirt, paper debris, ink skin on printing plate/cylinders, prevent regular wash blanket cylinder.
- bad register- colours protrudge beyond edge of 4 colour separations, make image out of focus, prevent regular inspection of registration marks to line up 4 colour separations exactly.
- Printers mark- aid in QC, e.g. colour bars vital information on printing press and inks used, contain range tests, some visual made by operator, some use densitometer (thick ink on paper)
- Registration marks help align 4 colours form full image, or look off centre, or blurry.
Total Quality management
- TQM or TQC, strategic integrated system achieve customer satisfaction by applying QA procedures at every stage of production process.
- TQM based all members organisation participating in continual improvement of processes, products, services, and overall culture work.
- Each department of company treated as client, ensure high standard service/attention to detail, when dealing between departments
- British Standards Institute (BSI)- operate quality management system any orginisation can be accredited to help produce products consistent high quality, known as ISO 9000 series standards, worlds most established quality framework, used 3/4 million orginisations, in 161 countries. If accredited, assured quality of product/service. Benefits to:
- Customers and Users- products conform to requirement, dependable, reliable, available when needed, maintainable.
- People in orginisation- better work conditions, increase job satisfaction, improve health and safety, improve morale.
- Owners and investors- increase return investment, improve operational results, increased market share, inscreased profits.
- Society- fulfil legal/regulation requirements, improve health/safety, reduce environment impact, increase security.
- National standards- e.g. British Standards (BS), produced by country's national body, in UK BS developed together with government, businesses and society, some enforced by regulation, most standards are voluntary.
- European standards- (EN), produced by European Committee for Standardisation (CEN), memers are NSBs of EU countries, in UK adopted as British Standards (BS EN).
- International standards- (ISO), produced International Orginization for Standardisation, members are NSBs of countries all over world, BSI leading member of ISO, represents UKs interests in development of international standards, decide what standards to adopt (BS ISO)
- Kitemark and CE marking- Kitemark originally introduced in UK only, now worldwide mark of quality, have associated with product/service certifies complies particular standard.
- Letters CE on product are manufacturer's claim product meets requirements all relevem European Directives, many products covered these directives, and some e.g. toys, it is a requirement to have a CE mark, shows product achieve minimum level quality, ensures can be moved freely throughout the European Single Market.