Understanding Inspection and Metrology
Inspections in the manufacturing process are often used for compliance or non-compliance matters. The equipment used is able to detect any abnormalities such as deviation in surface finish, quality, and dimensionality. Through inspection, you can detect abnormalities in the part which would otherwise be imperceptible to the human eye.
However, the process does not predict where defects will take place but rather highlights them for addressing in part revisions prior to manufacturing. If several defects are found they can be directly compared to CAD data, and an analysis sheet can be created highlighting the deviations from the original design. What this ensures is that when you go to manufacture your parts, they are within your engineering specifications, enabling you to avoid massive retooling or reworking costs associated with poor part manufacturing.
Metrology pertains to quality assurance methods used to calibrate the machines used during the production process to measure the subject parts. Metrology is often co-related to measurement, but it involves a more in-depth process that factors inaccuracy and errors as well as the mechanisms and performance of the metrology equipment being used. If there are no pattern measurements found within a specific range, a manufactured device is considered to be defective as it does not operate within its design specifications. This in turn requires the part to be reworked and revised to meet the desired specifications.