Design for manufacture and project management · Designing and making principles
Revision notes
Quality Assurance
Quality assurance (QA) consists of planned procedures and policies used throughout design and manufacture to prevent defects, reduce waste and ensure products are produced accurately and within acceptable tolerances.
QA plans for quality; QC checks whether the required quality has been achieved. QA is therefore preventative and process-focused, while QC is inspection and testing focused.
Quality assurance in practice
QA can include checking and approving suppliers, reviewing drawings and specifications before manufacture, workforce training, maintaining and calibrating machinery, standardising working procedures, documenting processes and planning quality checks at critical stages.
The aim is to design quality into the process so faults are less likely to occur, rather than relying only on detecting faulty products at the end.
Total Quality Management (TQM)
Total Quality Management (TQM) involves the whole workforce in continuous improvement. Quality is treated as everyone’s responsibility, with workers identifying problems and improving processes so products are made correctly first time. This can reduce defects, waste, rework and customer complaints.
Six Sigma
Six Sigma is a data-driven approach used to reduce defects and variation in manufacturing. A common improvement method is DMAIC: Define the problem, Measure current performance, Analyse causes, Improve the process and Control the improvement.
Scrum and critical path analysis
Scrum is an iterative project-management approach in which work is organised into short stages or sprints, with regular review and communication. It can help teams identify problems early and continually improve a product or process.
Critical path analysis (CPA) identifies the sequence of activities that determines the minimum completion time for a project. It helps manufacturers plan resources and timings so critical tasks are completed when required and delays can be managed.
QA vs QC — exam distinction
QA = preventing problems by controlling the system and process. QC = finding problems by monitoring, measuring, checking and testing outputs.
For example, training an operator and calibrating a machine are QA; measuring a finished component with a micrometer to check its tolerance is QC.
Planning, quality assurance and quality control help production remain accurate, efficient and consistent.Vacuum forming: a heated thermoplastic sheet is drawn over a former and held while it cools.Injection moulding: granules are melted and driven by a screw through a nozzle into a closed mould.Extrusion forces softened material through a shaped die to produce a continuous cross-section.Blow moulding: air expands a hot polymer parison against the inside of a mould.Rotational moulding coats the inside of a heated rotating mould before the hollow product cools.Compression moulding uses heat and pressure to form a measured charge inside a mould.A pattern forms a cavity in sand before molten metal is poured, cooled and removed.Die casting injects molten metal into a reusable metal die under pressure.Investment casting forms a ceramic mould around a sacrificial pattern for detailed components.MIG welding feeds a consumable wire electrode into a gas-shielded weld pool.TIG welding uses a non-consumable tungsten electrode and separate filler where required.Spot welding clamps sheet between electrodes and creates localised heat through electrical resistance.Steam softens lignin so timber can be bent around a former and held until dry.Thin veneers are glued and clamped around a former to create strong curved components.Flexography uses a relief plate and rollers to transfer ink to the substrate.Offset lithography transfers the image from plate to blanket cylinder and then to the substrate.Screen printing pushes ink through open areas of a mesh stencil onto the substrate.A focused laser follows a programmed path while assist gas helps clear the cut.Milling removes material with a rotating multi-point cutter while the work is accurately positioned.In turning, the workpiece rotates while a cutting tool removes material to create cylindrical forms.FEA divides a model into elements so stresses and deformation can be calculated.CFD predicts how fluids move around or through a product.A go/no-go gauge quickly checks whether a feature lies within its permitted tolerance.Vernier callipers measure external, internal and depth dimensions accurately.A micrometer uses a precision screw to measure small dimensions accurately.A tensile test records how a standard specimen responds as an increasing axial load is applied.Hardness tests compare resistance to permanent indentation under controlled conditions.Anthropometric data provides measured human dimensions for designing appropriate product sizes and clearances.Ergonomics applies knowledge of people to improve comfort, safety, usability and performance.Bauhaus design favoured functional forms, modern materials and design suited to industrial production.Art Deco is recognisable through geometric decoration, symmetry, luxury materials and machine-age influence.Memphis challenged restrained modernism with bold colour, pattern, geometry and playful forms.Arts and Crafts valued skilled making, natural inspiration, material honesty and resistance to poor-quality mass production.The life-cycle model helps explain how sales, competition and redesign priorities change over time.Sustainable design decisions should reduce resource use and keep products and materials useful for longer.
ACTIVE RECALL
Think you have got this topic?
Test yourself before moving on, or use flashcards for a quick recall session.
