Quality control and testing

Quality Control in Manufacturing

Quality Assurance (QA): This refers to the systematic activities implemented in a quality system to ensure that the product or service satisfies given requirements. It is the systematic measurement, comparison with a standard, monitoring of processes and an associated feedback loop.
Statistical Process Control (SPC): A mathematical method using the collection of numerical data through samples taken from the process we are controlling. SPC can be applied to any process where the conforming product output can be measured.
Quality Control (QC): This is a reactive process and aims to identify and correct defects in finished products. It involves routine testing of products to uncover defects and reporting to management who make the decision to allow or deny the release.

Types of Testing

Destructive Testing: These tests are generally much easier to carry out, yield more information, and are easier to interpret than nondestructive testing. Destructive testing is most suitable, and economic, for objects which will be mass-produced, as the cost of destroying a small number of pieces is negligible.
Non-Destructive Testing (NDT): This covers a wide group of analysis techniques used in science and industry to evaluate properties of a material, component, or system without causing damage. Methods could involve dye penetration tests or ultrasonic tests.
Hardness Testing: This measures the resistance of a material to indentation or scratching. It’s typically conducted by pressing a hard substance (like a diamond or hardened metal ball) into a test piece under a specific load.
Tensile Testing: This evaluates how a material reacts to forces being applied in two different directions, pulling the material apart. This testing method allows us to find a material’s strength, ductility, yield point, and other related mechanical properties.

Product and Process Approval

First Article Inspection (FAI): This verifies that the manufacturing process is capable of producing parts and assemblies that meet requirements. One of the first production runs is inspected and tested to ensure it functions as expected, before mass production begins.
Production Part Approval Process (PPAP): This is used by the automotive industry to establish confidence in component suppliers and their production processes, by demonstrating that all customer engineering design record and specification requirements are understood by the supplier and that the production process has the potential to produce product consistently meeting these requirements.
Final Inspection: This is a complete and final review of the manufacturing process, completed items, and documentation. This step is typically done at the end of production to ensure that all work orders have been completed, no steps were missed, and all functionality and performance tests have passed.

Surface Finishing

Surface Roughness: This involves the minor deviations of a surface from the perfectly smooth ideal (a true plane). Surface roughness is a measure of the texture of a surface.
Surface Treatments: These are processes that change the surface of a material to achieve a specific property. These treatments can be used to improve hardness, corrosion resistance, or aesthetic appeal of the part. Examples include heat treatment, plating, and painting.

Specification and Standards

ISO 9000 Series: This is a set of international standards on quality management and quality assurance developed to help companies effectively document the quality system elements to be implemented to maintain an efficient quality system.
British Standards (BS): These are the standards produced by BSI Group which is incorporated by a royal charter. Standards provide people and organisations with a basis for mutual understanding, and are used as tools to facilitate communication, measurement, commerce and manufacturing.
Company Specifications: These are detailed requirements that a potential contractor’s offer must meet. The company specification often include drawings and a listing of materials with specified quality to be used.