Managing Quality & Quality Control Notes

Managing Quality & Quality Control Notes

Quality and Strategy

  • Companies achieve a competitive advantage through:
  • Differentiation: Unique products that stand out.
  • Cost Leadership: Producing at a lower cost than competitors.
  • Response: Quick adaptation to customer needs.
  • Examples:
  • Bose Corp: Differentiates its stereo speakers by defining customer quality expectations.
  • Nucor Steel: Produces quality steel at low cost through efficient processes.
  • Dell: Rapid response through custom-built personal computers in hours.

Quality and Profitability

  • Improvements in Quality:
  • Can lead to increased sales and reduced costs.
  • Increasing Sales via Quality Improvement:
    1. Speed Response: Higher quality systems lead to faster response rates and lower lead times.
    2. Flexible Pricing: Ability to offer competitive pricing with better quality.
    3. Improved Reputation: Better quality enhances brand image.
  • Reducing Costs through Quality Improvement:
    1. Unspecified improvements and strategies to manage costs.

Cost of Quality

  • Definition: Total cost of efforts to achieve product quality, including:
  • Cost of conformance: effort to meet quality requirements.
  • Cost of non-conformance: costs resulting from failing to meet the requirements.
  • Types of costs:
  • Cost of Conformance:
    • Prevention: Costs related to preventative measures (e.g., employee training, quality systems).
    • Appraisal: Costs for measuring and auditing quality (e.g., inspections).
  • Cost of Non-Conformance:
    • Internal Failure: Costs incurred before delivery to customers.
    • External Failure: Costs incurred after delivery to customers.
    • Warranty claims, customer dissatisfaction, and potential legal costs.

Total Quality Management (TQM)

  • Concept: Integration of all functions and processes within an organization for continuous improvement to meet customer satisfaction.
  • Requirements of TQM:
  • Meeting customer requirements.
  • Doing things right the first time.
  • Consistency and reduction of variation.
  • Continuous improvement.
  • Quality in every aspect of operations.

Concepts of TQM

  1. Continuous Improvement: Ongoing efforts to improve products and processes.
  2. Six Sigma: A data-driven approach to eliminate defects and improve quality.
  3. Employee Empowerment: Involving employees in decision-making.
  4. Benchmarking: Comparing organizational practices to industry bests.
  5. Just-in-Time: Inventory strategy to improve efficiency and decrease waste.
  6. Taguchi Concepts: Emphasizing the design of quality products and processes.
  7. Knowledge of TQM Tools: Familiarity with tools that aid in quality management.

Continuous Improvement Process (CIP)

  • Acknowledges ongoing change in business practices and technology.
  • Four-step Model of Change:
  1. Plan: Understand client needs and expectations.
  2. Do: Execute plans through processes.
  3. Check: Ongoing review of processes; address issues accordingly.
  4. Act: Implement improvements for reliability and quality.

Six Sigma

  • Developed by Motorola and popularized by companies like GE.
  • Definitions:
  1. Statistical representation (3.4 defects per million opportunities).
  2. Aims to reduce defects, costs, and improve customer satisfaction.

Taguchi Concepts

  • Emphasizes that most quality problems arise from poor product/process design.
  • Three main ideas:
  1. Quality Robust Products: Designed to perform under various conditions.
  2. Quality Loss Function: Identifies costs associated with deviations from targeted quality.
  3. Example of Taguchi Concept: Resistors produced with a tolerance of ±5 ohms but instead of being acceptable, any deviation incurs a cost reflecting customer dissatisfaction.

Tools of TQM

  • Check Sheets: Used for collecting data to identify quality problems.
  • Pareto Diagrams: Display vital few causes responsible for most problems (80/20 rule).
  • Histograms: Visual bar charts of data distributions.
  • Scatter Diagrams: Show relationships between variables.
  • Cause and Effect Diagrams (Fishbone): Map potential causes of quality issues.
  • Flow Charts: Visual representation of processes to identify improvements.
  • Control Charts: Monitor processes over time to identify stability.

Control Charts and Statistical Process Control (SPC)

  • Purpose: Monitor production standards and processes, identifying variations.
  • Distinguishes between natural and assignable cause variations.
  • Control limits defined by process statistics (mean and standard deviation).

Performance Measurements

  • Two approaches: Variables (e.g., weight, length - continuous measurement) and Attributes (counting defects - binary).

Sampling and Distributions

  • Sampling is necessary for estimating population measures.
  • Central Limit Theorem: The distribution of sample means will tend to be normal regardless of the population distribution.

Control Limits and Process Evaluation

  • Control limits help determine if a process is in statistical control.
  • R-charts and x-charts monitor dispersion and central tendency, respectively.

Control Charts for Attributes

  • p-Charts for proportions defective: Based on binomial distribution for yes/no decisions.
  • c-Charts for counting defects: Uses Poisson distribution to represent the number of defects.
  • Practical applications shown in examples, like analyzing patient wait times to manage clinic processes effectively.

Examples of Control Charts (p-Charts)

  1. An example of a p-chart demonstrating sample proportions of defects used in a medical clinic setting.