Quality

Quality assurance

These are the planned activities used by the manufacturer to monitor the quality of a product from its design and development stage, through its manufacture, to its end use, and a degree of customer satisfaction. QA is an assurance that the end product fulfils all of its requirements for quality.

• QA ensures a product is fit for purpose using thorough testing throughout the design and development stage.
• It includes regulation of the quality of raw materials and components that the manufacturer buys in order to start production.
• QA systems monitor the quality of components, products and assemblies in production through a series of quality control checks, test and inspection processes.
• QA supplies fact-based evidence for quality management systems to inspire external confidence to customers and other stakeholders that a product meets all of their need and expectations.

Quality control

QC is part of the achievement of quality assurance. It involves the actual activities used by a manufacturer to ensure a high-quality product is produced by means of inspection and testing.

Inspection:

Inspection is the sampling and examination of components or products to check that they are within a specified tolerance. Tolerance is the degree to which a component is acceptable in order to function in accordance with its specification.

Three main levels of inspection

100% inspection of all units

Normal inspection using a sampling plan under ordinary circumstances.

Reduced inspection is used in some inspection systems as an economy measure when the level of submitted quality is 'sufficiently good'. 

Testing 

Testing is concerned with the product's performance. Tests are carried out in laboratory conditions with strict control procedures to ensure that the results obtained are accurate. Tests are carried out on materials, components and the final product using two main methods.

Non-destructive testing (or failure testing), where the product is tested until it shows signs of failing, e.g. cracking, to determine how much force is needed to deform it.

Testing to destruction where the product is destroyed under controlled conditions and monitored to gather valuable research.

PROBLEM: SET OFF

DESCRIPTION: The ink from one sheet smudges onto the underside of the following sheet.

QUALITY CONTROL: Use of sufficient anti-set-off spray, sufficiently quick drying inks.

PROBLEM: COLOUR VARIATION

DESCRIPTION: The printer does not maintain consistent colour throughout the run.

QUALITY CONTROL: Use of colour bars and regular densitometer readings.

PROBLEM: HICKIES

DESCRIPTION: Small areas of unwanted solid colour surrounded by an unprinted 'halo' area caused by specks of dirt.

QUALITY CONTROL: Regular washing of the blanket cylinder.

PROBLEM: BAD REGISTER

DESCRIPTION: Colours protude beyond the edge of the four colour seperations, making the image look out of focus.

QUALITY CONTROL: Regular inspeciton of registration marks to line up the four colour seperations exactly.

Total quality management

This is the strategic integrated system for achieving customer satisfaction by applying QA procedures at every stage of the production process. TQM is based on all members of an organisation participating in the continual improvement of processes, products, services, and the overall culture in which they work. Each department in a company is treated as a client, therefore ensuring high standards of service and attention to detal when dealing between departments. For example, a production team must produce a high-quality component that the assembly team know is quality assured and will therefore fit perfectly.

One-off

Applications:

Prototype and architectural models, shop signage, vinyl stickers for commercial vehicles, etc.

Advantages:

• Made to exact personal specifications.
• High-quality materials used.
• Highly skilled craftsperson ensures high-quality product.

Disadvantages:

• Expensive final product in comparison to larger scales of production.
• Generally labour intensive and be a relatively time-consuming process.

Batch

Applications: 

Commercially printed materials e.g. magazines and newspapers.

Advantages:

• Flexibility in adapting production to another product.
• Fast response to market trends.
• Identical batches of products produced.
• Efficient manufacturing systems can be employed.
• very good enconomies of scale in bulk buying of materials.
• Lower unit costs.

Disadvantages:

• Poor production planning can result in large quantities of products having to be stored, incuring storage costs.
• Frequent changes in production can cause costly re-tooling, reflected in retail price.
  

Mass

Applications: Electronic products, e.g. mobile phones and games consoles, commercial packaging, etc.

Advantages:

• Highly automated and efficient manufacturing processes.
• Specialisation of workforce to specific tasks.
• Rigorous quality control ensures identical goods.
• Excellent economies of scale in bulk buying of materials.
• Increased production means that set-up costs are quickly recovered.
• Low unit costs and reduced labour costs.

Disadvantages:

• Low-skilled workfoce-low wages, repetitive nature of tasks leading to job dissatisfaction.
• Ethical concerns of manufacturing in developing countries i.e. 'sweat shops'.
• High initial set-up costs due to very expensive machinery tooling needs.
• Inflexible- cannot respond quickly to market trends.

Continuous

Applications: 

Packaging, e.g. cans and bottles for the drinks industry.

Advantages:

• As mass production.
• Extremely low unit costs.
• Runs continuously 24 hours, 7 days a week.

Disadvantages:

• As mass production.
• Very little flexibility at all as set up 24/7.

CAD (computer aided design)

Advantages:

• Even large and complicated designs can be drawn precisely, to very small tolerances, with all the information contained on a single drawing.
• It is easy to reproduce identical features of components in drawings using copy and paste commands or by adapting pre-drawn components.
• Changes are very easy to make using editing tools and the software will adapt the rest of the design automatically to acommodate these improvements.
• Designs can be stored and retrieved electronically on the network, on disc, on CD ROM or by using electronic devices. Allows open access to files.
• Multiple copies of a design can be created at the touch of a button and can be sent electronically across networks. Designers can simultaneously work on same design.
• Complicated tests can be carried out on-screen without the need to use expensive methods.
• A wide range of specialist tools can perform complex operations quickly and automatically speeding up the design process.
• The software can carry out complex calculations automatically.

CAD (computer aided design)

Disadvantages:

• CAD takes a long time to learn how to use the software.

Spirit varnishing

Process: A liquid sprayed onto the product after printing.

Uses: General purpose medium gloss applications.

Advantages:

• Medium gloss finish enhances visual impact.
• Good, low cost general purpose protective enhancing finish.
• Protects against scuffing.
• Can be applied at the same time as printing.

Disadvantages:

• Drying time can slow production.
• If not dry, surfaces will stick together.

UV varnishing

Process: A liquid is sprayed onto the product and dried rapidly using UV light.

Uses: Used where high gloos finish is required.

Advantages:

• Does not slow the manufacturing process significantly due to rapid drying process.
• Protects against scuffing.
• Can be applied at the same time as printing.

Disadvantages:

• Equipment is expensive.

UV spot varnishes

Process: UV sparkle varnish. Fragrance burst inks. Silver latex ''scratch offs''.

Uses: Various.

Advantages:

• Enhances functional and aesthetic properties.

Disadvantages:

• Additional process which raises costs.

Laminating

Process: The paper/board and polymer laminating film is passed between heated rollers under pressure. The heat activates the adhesive to bond the paper/board.

Uses: Orange juice cartons. Chocolate bar wrappers. Chocolate boxes.

Advantages:

• Adhesives can be activated by heat so they are easy to handle.
• Polymer laminates increase rigidity, strength, durability, stability and enhance aesthetics.

Disadvantages:

• Additional process which raises costs.

Hot foil blocking

Process: Thin polyester backed foli designs are pressed onto the product using heated die.

Uses: Book covers. Chocolate packaging. Premium packaging.

Advantages:

• Enhances visual impact.
• Dry process.
• 100% opaque.

Disadvantages:

• Costly process.
• Limited colours.
• Difficult to control accuracy of colour/shape.

Encapsulation

Process: The paper/board and double layered polymer laminated pouch is pressed between heated rollers. The heat activates the adhesive to bond it to paper/board.

Uses: Restaurant menus. ID cards. Signage.

Advantages:

• Liquid resistant.
• Wipe clean.
• Increases rigidity, strength, durability, stability and enhance aesthetics.

Disadvantages:

• Increase in costs and weight.

Embossing

Process: Paper/board is squeezed between two heated dies.

Uses: Paperback book covers. Chocolate packaging. Greetings cards.

Advantages: 

• Enhances aesthetics.
• Enhances tactile (feel) properties.

Disadvantages: 

• Increases costs.

Embossing

Process: Paper/board is squeezed between two heated dies.

Uses: Paperback book covers. Chocolate packaging. Greetings cards.

Advantages: 

• Enhances aesthetics.
• Enhances tactile (feel) properties.

Disadvantages: 

• Increases costs.

Die cutting and scoring

Process: Die cutting involves punching out, scoring and creasing. Blunt blades are used for creasing.

Uses: Packaging boxes. Card products.

Advantages: 

• Fast and accurate.

Disadvantages:

• Die-forms need to be replaced periodically.

Folding and spot gluing

Process: Packaging nets are produced in volume use automated folding machines. The fold is compressed by rollers. Spot glue is applied automatically and controlled by sensors.

Uses: Books and magazines. Packaging boxes. Card products.

Advantages: 

• Fast and accurate.

Disadvantages: 

• Constant QC checks need to be made to maintain accuracy.

Vinyl cutting

Process:

• Vinyl is clamped into plotter cutter.
• Drawing file is opened in CAD drawing program and sent to cutter.
• Design is scored and cut.
• Vinyl or card is removed.
• Waste is removed (weeding).
• Application tape is used to apply design to product.

Uses:

• Signage.
• Car and van graphics.
• Logos.

Vinyl cutting

Advantages:

• Designs can be applied easily 'on site'.
• By selecting different vinyl, designs can be made to be either permanent or removable.
• Flexible vinyl will adhere to curved surfaces.
• Designs can be printed onto vinyl.

Disadvantages:

• Slower than printing.
• Designs need to be relatively simple.
• Vinyl may degrade in time.
• Can leave marks on surface.

Polymers

Thermoplastic:  PET (Polyethylene Terephthalate)

Properties:

• Excellent barrier against atmospheric gases.
• Prevents gas from escaping package.
• Does not flavour the contents.
• Sparkling 'crystal clear' appearance.
• Very tough.
• Lightweight- low density.

Applications:

• Carbonated (fizzy drinks) bottles.
• Packaging for highly flavoured foods.
• Microwavable food trays.

HDPE (High Density Polyethylene)

Properties:

• Highly resistant to chemicals.
• Good barrier to water.
• Tough and hard wearing.
• Decorative when coloured.
• Lightweight and floats on water.
• Rigid.

Applications:

• Unbreakable bottles (for washing up liquid, detergents, cosmetics, toiletries, etc.).
• Very thin packaging sheets.

PVC ( Polyvinyl Chloride)

Properties:

• Weather resistant- does not rot.
• Chemical resistant- does not corrode.
• Protects products from moisture and gases while holding in preserving gases.
• Strong, good abrasive resistance and tough.

Applications:

• Packaging for toiletries, pharmaceutical products, food and confectionary, water and fruit juices.

LDPE (Low density Polyethylene)

Properties:

• Good resistance to chemicals.
• Good barrier to water, but not gases.
• Tough and hard wearing.
• Decorative when coloured.
• Very light and floats on water.
• Very flexible.

Applications:

• Stretch wrapping (cling film).
• Milk carton coatings.

PP (Polypropylene)

Properties:

• Lightweight.
• Rigid.
• Excellent chemical resistance.
• Versatile- can be stiffer than polyethylene or very flexible.
• Low moisture absorption.
• Good impact resistance.

Applications:

• Food packaging- Yoghurts and margarine pots, sweet and snack wrappers.
• Used for laminated paper and board.

PS (Polystyrene)

Rigid polystyrene:

• Transparent and rigid.
• Lightweight and low water absorption.

Expanded polystyrene:

• Excellent impact resistance and good heat insulation.
• Durable, lightweight and low water absorption.

Applications:

Rigid:

• Food packaging, e.g. yoghurt pots, CD jewel cases, audio cassette cases.

Expanded:

• Egg cartons, fruit, vegetable and meat tray, cups etc. Packing for electrical and fragile products.