--- title: "Scope and objectives of metrology" subject: "Metrology" chapter: 1 key: "semester_3/metrology:scope-objectives-of-metrology" source: https://www.bctengineer.com/q/semester_3/metrology/scope-objectives-of-metrology site: BCT Engineering --- # Scope and objectives of metrology Metrology · Chapter 1: Introduction to Metrology - Asked in: year not given, 5 marks - Video: [introduction to metrology |objective of metrology | objectives of metrology |what is metrology](https://www.youtube.com/watch?v=y9_ZQoBMSno) — Modi Mechanical Engineering Tutorials - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_3/metrology/scope-objectives-of-metrology - Whole chapter: https://www.bctengineer.com/md/semester_3/metrology/chapter-1 ## Question Define metrology. Explain the scope and the main objectives of metrology in an engineering industry. ## Short answer Metrology is the science of measurement covering theory and practice of measuring physical quantities with required accuracy. Its scope includes instrument calibration, establishing traceability to standards, error analysis, and inspection of dimensions and form. Objectives are to evaluate product conformity, ensure interchangeability, determine process capability, and minimize inspection costs through early defect detection. ## Answer **Metrology** is the science of measurement. It covers the theory and practice of measuring physical quantities (length, angle, mass, time, temperature and so on) with the required accuracy, together with the standards, instruments and methods used. #### Scope - Selection, design and calibration of measuring instruments and standards. - Establishing units and their traceability to national and international standards. - Study of measurement errors, uncertainty and the capability of instruments. - Inspection and testing of dimensions, form, surface finish, screw threads and gears. - Checking the geometry and accuracy of machine tools. - Supporting quality control, interchangeable manufacture and legal trade. #### Objectives 1. To evaluate the performance of a new product or design against specification. 2. To determine the process capability and to select a suitable process or machine. 3. To decide the accuracy needed so that the instrument is neither inadequate nor needlessly costly. 4. To inspect raw material, components and finished products so that they are within limits and interchangeable. 5. To maintain the accuracy of measuring instruments by periodic calibration. 6. To minimise the cost of inspection and rejection by early detection of defects. 7. To standardise methods of measurement and to prepare gauges, drawings and specifications. 8. To find the causes of errors and rejected parts so that the process can be corrected. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which statement best defines metrology? A. The science of measurement, including theory, practice, standards, instruments and methods B. The study of metals and their properties C. The inspection of finished products only D. The manufacture of precision gauges Answer: A. Metrology is the science of measurement covering measuring physical quantities with required accuracy, along with the standards, instruments and methods used. (Key point: Definition of metrology) 2. Why is deciding the required accuracy an objective of metrology? A. So the most accurate instrument available is always used B. So the instrument is neither inadequate nor needlessly costly C. So that inspection can be skipped D. So that all instruments have the same least count Answer: B. Choosing the right accuracy avoids using an instrument that is too poor for the job or one that is unnecessarily expensive. (Key point: Accuracy needed for an instrument) 3. What is the purpose of periodic calibration in metrology? A. To reduce the number of parts inspected B. To change the specification of the product C. To maintain the accuracy of measuring instruments D. To remove the need for standards Answer: C. Objective 5 is to maintain the accuracy of measuring instruments by calibrating them periodically. (Key point: Role of periodic calibration) 4. How does metrology help to minimise the cost of inspection and rejection? A. By accepting all parts within a wider tolerance B. By measuring only the finished products C. By using only the cheapest instruments D. By detecting defects early and finding causes of errors so the process can be corrected Answer: D. Early detection of defects and finding the causes of rejected parts allow the process to be corrected, cutting rejection cost. 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