Commercial Production / 10.4 /
Quality Management
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Quality management focuses on producing products of consistent required quality. Designers should ensure that the quality of products is consistent through development of detailed manufacturing requirements. They also need to focus on the means to achieve it. The importance of quality management through quality control (QC), statistical process control (SPC) and quality assurance (QA) reduces the potential waste of resources.
Quality Control, Statistical Process Control, and Quality Assurance are all part of Quality Management. Quality management aims to ensure customer loyalty, profitability and to reduce liability risk.
10.4.1 | Quality control (QC)
10.4.1 | Quality control (QC)
Quality control is the conducting of tests and measurements to ensure a product’s qualities are within the tolerances determined in the technical specifications of the design. Tolerance is the allowable amount of variation within a particular quality. For example, the weight tolerance for a high-performance bicycle frame might be +/- 10 grams from its specified weight of 1850 grams.
Specifications and tolerances for a product are defined at the design stage, but they need to be checked and rechecked throughout the production process. Tolerance might be defined for properties of an end-product, but also for properties at intermediate stages of production. Tolerance might even be determined for the properties of the machine creating the product or part. Different brands of machines can also be said to operate at different tolerances.
Quality control can be done in a number of ways including,
Continuous monitoring of a property.
Inspection of random samples (sampling).
Non-destructive testing - Testing a product or part by measuring physical properties. The product itself is not damaged or changed in the process: Weighing, checking colour, confirming dimensions.
Destructive testing - Testing a product or part that destroys or physically alters the part. These are usually mechanical properties such as heat resistance, compression, and toughness.
10.4.2 | Statistical Process Control (SPC)
10.4.2 | Statistical Process Control (SPC)
The process control charts to the left show the testing of a property of a number of the same parts. The upper and lower specification limits are defined by the purple lines. The green dotted lines are the Upper and Lower Control limits. The area between the green dotted lines is the tolerance range. The dots represent the measurement of individual items.
Manufacturers will typically calibrate their machines to achieve the mean of these data points while allowing for tolerances that fit between the UCL and the LCL.
Statistical Process Control (SPC) is a mathematical approach to ensure a process operates efficiently. By mathematically analyzing quality control data SPC processes can:
Identify abnormalities
Prevent ‘out of control’ situations
Identify inefficiencies
Identify opportunities for improvement
Identify the need for maintenance or (re)calibration
Facilitate timely decision-making
The application of SPC is broad and includes for example:
Monitoring of machine performance and maintenance needs on production lines.
Airlines use data on flight delays, lost luggage, customer satisfaction, and waiting time at check-in to identify inefficiencies
Car manufacturers use data on types and frequency of repairs, rate of wear and tear on parts such as brake pads, and data from car accidents and crashes to improve the automobile's quality and safety.
Grocery Stores use data on waiting time to check out, frequency of out-of-stock items, quality of food items, cleanliness, customer complaints, and checkout register errors.
10.4.3 | Quality Assurance (QA)
10.4.3 | Quality Assurance (QA)
Quality Assurance (QA) are the combined protocols and regulations instituted in a production or service process to reduce or avoid errors or defective products being delivered to the customer. Quality assurance includes:
Process documentation requirements
Regulation of quality of raw materials ( By identifying inferior materials earlier in the producing stage, costly errors, waste, and downtime can be avoided later on)
Workplace safety
Training and professional development requirements
Empowering workers to be responsible
Waste reduction
Communication and Collaboration
QA sets standards of quality for all stages of commercial production, beginning with the raw materials and all the way through the delivery of the product to the customer.
Many quality standards are determined by national and international organizations. The International Organization for Standardization (ISO) has developed international standards for products and processes in a wide array of industries. Legislation in the European Union determines quality standards that products (and production processes) and services must meet to be allowed to be introduced in the EU. Even factories operating outside of the EU need to meet these standards.
While QC, SPC, and QA all play vital roles in achieving quality (quality management), they each have distinct purposes and approaches.
Quality Assurance (QA)
Quality Assurance (QA)
Focuses on prevention: Ensures the processes are designed and implemented effectively to deliver high-quality products or services. QA Defines quality standards, establishes procedures, conducts audits, and reviews documentation.
Statistical Process Control (SPC)
Statistical Process Control (SPC)
Focuses on monitoring: A tool used within QA to statistically monitor and analyze process data to identify deviations from set standards. SPC collects and analyzes data, constructs control charts, identifies trends and variations, and recommends corrective actions.
Quality Control (QC)
Quality Control (QC)
Focuses on inspection: Verifies that the products or services meet established quality standards.
Activities: Performs inspections, testing, and measurements, identifies and rectifies defects, and reports quality data. - Checking the final product to ensure it meets the desired quality standards.
Summarizing the differences:
Timing: QA happens before production, SPC during production, and QC after production.
Focus: QA focuses on processes, SPC on data and monitoring, and QC on product inspection.
Outcome: QA aims to prevent defects, SPC to identify deviations, and QC to identify defects.
Analogy
Analogy
Imagine building a house:
QA is the architect who designs the blueprints and ensures the construction plan is sound.
SPC is the supervisor who monitors the construction process and identifies any deviations from the plan using data and charts.
QC is the inspector who checks the finished house to ensure it meets building codes and regulations.
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