15.5 Quality Assurance & Quality Control

Definition: Quality assurance is a procedure or system followed to achieve a desired level of quality.
Effective QA Procedures Include:
- Measurement of variables.
- Comparisons against specifications.
- Constant monitoring of processes.
- Implementing feedback loops to prevent errors.
Process Orientation: QA is process-led, focusing primarily on defect prevention.

You need to know about QA for:
- Waste reduction.
- Accurate manufacturing.
- Applying tolerances.
Familiar QA Systems Include:
- Total Quality Management (TQM)
- Scrum
- Six Sigma
- Critical Path Analysis (CPA)

Flowcharts:
- Definition: A flowchart is a diagram that shows a workflow or process, usually read from top to bottom and left to right.
- Purpose: They highlight critical control points and allow feedback, aiding manufacturers to identify possible problems such as bottlenecks.

Origin: Named after Henry Gantt, developed in the early 19th century.
Purpose: A widely used project management tool for showing:
- Phases of a project.
- Individual tasks.
- Key milestones.
- Required resources.
Structure: Tasks are displayed on the vertical axis; timings on the horizontal axis.

Definition: In Japanese, Kaizen means "change for the good." It is the principle behind lean manufacturing.
Aim: To improve efficiency and eliminate waste in all areas of production.
Reliance: Kaizen relies on:
- Employee collaboration.
- Evaluation and innovation.
- Practical improvements.

Foundation: Based on Kaizen principles, TQM is customer-focused and process-centred.
Key Features Include:
- Integrated strategies and systems.
- Employee involvement.
- Effective communication.
- Constant feedback mechanisms.
- Commitment to continuous improvement.

Definition: Scrum is a quality-driven, agile framework for managing product development and problem-solving.
Etymology: Named after a rugby scrum, emphasizing teamwork.
Initiation: Initiated by the product owner who creates a product backlog, listing items for market introduction.
Scrum Master Role: Leads the scrum team through a series of sprints, characterizing these as focused tasks.

Sprint Backlog: A list of products to produce in the upcoming sprint.
Scrum Board: A visual representation of tasks assigned to each team member, tracking their progress.
Types of Meetings:
- Sprint Planning: Set up sprint parameters.
- Daily ‘Stand-Ups’: Check on progress and plans.
- Sprint Review: Deliver results and receive feedback.
- Sprint Retrospective: Reflect on improvements for future sprints

Origin: Created at Motorola in 1986 to enhance process and management performance.
Methodology: Follows a cycle inspired by W. Edwards Deming's ‘Plan-Do-Study-Act’ (PDSA).
Phases: Comprised of five phases:
- Define: Identify the problem and project goals.
- Measure: Collect data and determine current performance.
- Analyse: Identify root causes of defects.
- Improve: Implement solutions to eliminate causes of defects.
- Control: Monitor improvements to sustain results.
Defects Measurement: The term 'Six Sigma' refers to allowing a maximum of 3.4 defects per million opportunities (DPM).
Corporate Use: Widely adopted by large corporations for efficiency and quality improvement.

Methods Used:
- Project Evaluation and Review Techniques (PERT).
- Critical Path Analysis (CPA), also known as Critical Path Method (CPM).
Function: Both are project modelling tools for mapping the sequential stages of a project.
Arrow and Node Diagrams: Used in PERT and CPA for visual representation, calculating the longest pathway of activities.
Float: Some tasks may have float, indicating they can be delayed without extending the overall project timeline.

Methodology: A six-step method for planning sequential activities:
- Stage 1: Specify each task involved.
- Stage 2: Sequence activities logically.
- Stage 3: Draw a network diagram.
- Stage 4: Estimate duration for each task.
- Stage 5: Identify the critical path, the longest sequence of tasks.
- Stage 6: Update the diagram to reflect progress during execution.

Functionality: Similar to CPA, PERT does not provide a single estimated project duration but allows for realistic timeframe calculations using three variables:
- Optimistic Duration (O)
- Most Likely Duration (M)
- Pessimistic Duration (P)

Definition: Quality control ensures that product standards are met by using various tools to check dimensional accuracy and tolerances.
Workshops: Discuss the features of machines in school workshops that facilitate accuracy in quality control.
Production Checks: Explore potential quality control checks for large-scale production environments.

Importance: Visual checks are conducted throughout the production process to verify:
- Compliance of supplied materials with manufacturer requirements.
- Tolerance of parts and components.
- Match of finished products to the product design specification.
- Compliance with relevant industry standards.
Random Spot Checks: Often employed to ensure ongoing quality during production workflows.

Requirements: Accurate measurement of materials necessitates reference or ‘datum’ points.
Measurement Tools Include:
- Traditional instruments: rules, squares, callipers, and gauges.
- Enhanced tools: digital micrometres, laser scanners, and probe scanners.
Dial Test Indicator (DTI): Uses a probe for precise measurement from a designated reference point.

Definition: Tolerance refers to the allowable margin for error in high-volume production, applicable to various dimensions:
- Hole depth, length, angle, thickness, weight, elasticity, etc.
Use of Go-No Go Gauges: Employed to test components to ensure they fall within given tolerances, rejecting products that do not comply during quality control checks.

Methods:
- Ultrasound and X-ray analysis are used in NDT to examine internal structures and measurements.
- These technologies help identify wall thickness and detect internal flaws not visible externally.
Utility: Discuss types of faults identifiable by NDT methods.