INTRODUCTION TO MEASUREMENT AND QUALITY CONTROL

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• Q1: Define Metrology.
  Ans: Metrology is the science of measurement. It deals with the methods, instruments, and standards used to measure physical quantities accurately.
• Q2: Which is the most important measurement in metrology?
  Ans: The most important measurement in metrology is Length.
  It is measured by different methods and forms the basis of many other measurements.
• Q3: State the importance of metrology.
  Ans: The importance of metrology is as follows:

  • ➔ Ensures accuracy in measurements
  • ➔ Helps in maintaining quality of products
  • ➔ Provides standardization in manufacturing
  • ➔ Reduces errors and wastage
  • ➔ Helps in interchangeability of parts
• Q4: Name some instruments used in metrology.
  Ans: Some instruments used in metrology are:

  • ➔ Vernier Caliper
  • ➔ Micrometer Screw Gauge
  • ➔ Steel Rule
  • ➔ Dial Indicator
  • ➔ Slip Gauges
• Q5: What is Mass production?
  Ans: Mass production is the process of manufacturing large quantities of identical products using machines and standardized methods.
• Q6: Name the parts of the human body that were considered the base of measurement.
  Ans: The parts of the human body used as base of measurement are:

  • ➔ Foot
  • ➔ Hand span
  • ➔ Cubit (elbow to fingertip)
  • ➔ Finger width
• Q7: Define measurements.
  Ans: Measurement is the process of comparing an unknown quantity with a standard known quantity to determine its value.
• Q8: Briefly state the history of measurements.
  Ans: In ancient times, measurements were based on human body parts like foot and cubit.
  These were not accurate, so standard systems were developed later.
  Modern systems like SI units are now used for accurate and uniform measurements.
• Q9: State the purpose of measurements.
  Ans: The purpose of measurements is:

  • ➔ To determine size, shape, and dimensions
  • ➔ To ensure accuracy in manufacturing
  • ➔ To maintain quality control
  • ➔ To ensure proper fitting of parts
• Q10: Define Precision measurement.
  Ans: Precision measurement is the measurement that gives very accurate and consistent results with minimum error.
• Q11: Define Non-Precision measurement.
  Ans: Non-precision measurement is the measurement that is less accurate and may have a higher degree of error.
• Q12: What is meant by One Micron?
  Ans: One micron is equal to one-millionth of a meter.
  It is written as: 1 µm = 1 × 10^-6 m
• Q13: Define Quality Control.
  Ans: Quality Control is the process of ensuring that products meet the required standards and specifications.
• Q14: State four advantages of Quality Control.
  Ans: Advantages of Quality Control are:

  • ➔ Improves product quality
  • ➔ Reduces wastage and cost
  • ➔ Increases customer satisfaction
  • ➔ Ensures uniformity in production
• Q15: Define Measuring Systems.
  Ans: Measuring systems are standardized systems used to measure physical quantities like length, mass, and time.
• Q16: Name the Measuring Systems.
  Ans: The measuring systems are:

  • ➔ S.I System
  • ➔ F.P.S System
  • ➔ M.K.S System
  • ➔ C.G.S System
• Q17: What is the S.I Measuring System?
  Ans: The S.I (International System of Units) is a modern system of measurement used worldwide. It includes units like meter, kilogram, and second.
• Q18: What is the F.P.S Measuring System?
  Ans: The F.P.S system stands for Foot-Pound-Second system. It uses foot for length, pound for mass, and second for time.
• Q19: What is the M.K.S Measuring System?
  Ans: The M.K.S system stands for Meter-Kilogram-Second system. It uses meter for length, kilogram for mass, and second for time.
• Q20: What is the C.G.S Measuring System?
  Ans: The C.G.S system stands for Centimeter-Gram-Second system. It uses centimeter for length, gram for mass, and second for time.
• Q21: What is ISO?
  Ans: ISO stands for International Organization for Standardization.
  It is an international body that develops standards to ensure quality, safety, and efficiency of products and services.
• Q22: What are ISO Standards?
  Ans: ISO Standards are rules and guidelines developed by ISO to ensure that products and services are safe, reliable, and of good quality.
• Q23: What is ASTM?
  Ans: ASTM stands for American Society for Testing and Materials.
  It is an organization that develops technical standards for materials, products, systems, and services.
• Q24: What is BIS?
  Ans: BIS stands for Bureau of Indian Standards.
  It is the national standards body of India that ensures quality and standardization of products.
• Q25: What is ISA?
  Ans: ISA stands for International Society of Automation.
  It is an organization that sets standards related to automation and control systems.
• Q26: What is IEC?
  Ans: IEC stands for International Electrotechnical Commission.
  It prepares international standards for electrical and electronic technologies.
• Q27: What is the ABC Conference?
  Ans: ABC Conference refers to a meeting of countries to discuss and adopt international standards for measurement and engineering practices.
• Q28: What are ABC Countries?
  Ans: ABC Countries are:

  • ➔ A for America
  • ➔ B for Britain
  • ➔ C for Canada
• Q29: What is meant by minimum and maximum material condition?
  Ans: Maximum Material Condition (MMC) is the condition when a part contains the maximum amount of material (largest size for shaft or smallest for hole).
  Minimum Material Condition (LMC) is the condition when a part contains the least amount of material (smallest size for shaft or largest for hole).
• Q30: What is meant by the Nominal Size of any part?
  Ans: Nominal size is the approximate or general size of a part used for identification purposes.
• Q31: What is meant by the Basic Size of any part?
  Ans: Basic size is the exact theoretical size from which limits of size are calculated.
• Q32: What is Line Standard?
  Ans: Line standard is a type of measurement in which the length is measured as the distance between two lines marked on a scale.
• Q33: What is the End Standard?
  Ans: End standard is a type of measurement in which the length is measured as the distance between two flat surfaces or ends.
• Q34: Define Tolerance.
  Ans: Tolerance is the permissible variation in the size of a part. It is the difference between the maximum and minimum limits of size.
• Q35: State the importance of Tolerance.
  Ans: The importance of tolerance is:

  • ➔ Ensures proper fitting of parts
  • ➔ Allows easy manufacturing
  • ➔ Reduces production cost
  • ➔ Helps in interchangeability of parts
• Q36: State the types of Tolerance.
  Ans: Types of tolerance are:

  • ➔ Unilateral Tolerance
  • ➔ Bilateral Tolerance
  • ➔ Geometric Tolerance
• Q37: Define Unilateral Tolerance.
  Ans: Unilateral tolerance is a type of tolerance in which variation is allowed only in one direction (either positive or negative) from the basic size.
• Q38: Define Bilateral Tolerance.
  Ans: Bilateral tolerance is a type of tolerance in which variation is allowed in both directions (positive and negative) from the basic size.
• Q39: Define Geometric Tolerance.
  Ans: Geometric tolerance is the allowable variation in the shape, position, and orientation of a part.
• Q40: What is 5-M?
  Ans: The 5-M includes the following:

  • ➔ Manpower
  • ➔ Money
  • ➔ Machine
  • ➔ Measurement
  • ➔ Material
• Q41: Define Allowance.
  Ans: Allowance is the intentional difference between the sizes of two mating parts (shaft and hole) to achieve the desired type of fit.
• Q42: State the types of Allowance.
  Ans: Types of allowance are:

  • ➔ Clearance Allowance
  • ➔ Interference Allowance
• Q43: Define Clearance Allowance.
  Ans: Clearance allowance is the difference when the hole size is larger than the shaft size, allowing free movement between parts.
• Q44: Define Interference Allowance.
  Ans: Interference allowance is the difference when the shaft size is larger than the hole size, causing tight fitting between parts.
• Q45: Define Fit.
  Ans: Fit is the relationship between two mating parts (hole and shaft) that determines how they will fit together.
• Q46: State the types of Fit.
  Ans: Types of fit are:

  • ➔ Clearance Fit
  • ➔ Interference Fit
  • ➔ Transition Fit
• Q47: Define Clearance Fit.
  Ans: Clearance fit is a fit in which there is always a gap between the hole and shaft, allowing free movement.
• Q48: Define Interference Fit.
  Ans: Interference fit is a fit in which the shaft is larger than the hole, resulting in a tight fit that may require force to assemble.
• Q49: Define Transition Fit.
  Ans: Transition fit is a fit which may result in either a small clearance or slight interference between the parts.
• Q50: State the classification of Fits.
  Ans: The classification of fits are as follows:

  • ➔ Class-I: Loose Fit - Large Allowance
  • ➔ Class-2: Free Fit - Liberal Allowance
  • ➔ Class-3: Medium Fit - Medium Allowance
  • ➔ Class-4: Snug Fit - Zero Allowance
  • ➔ Class-5: Wringing Fit - Slightly Negative Allowance
  • ➔ Class-6: Tight Fit - Negative Allowance
  • ➔ Class-7: Medium Force Fit - Moderate Negative Allowance
  • ➔ Class-8: Heavy Force Fit - Maximum Negative Allowance
• Q51: What is Class-I Fit?
  Ans: Class-I fit is a loose fit with large allowance. It allows easy movement between parts.
• Q52: What is Class-2 Fit?
  Ans: Class-2 fit is a free fit with liberal allowance. It allows smooth and free movement.
• Q53: What is Class-3 Fit?
  Ans: Class-3 fit is a medium fit with moderate allowance. It provides a balance between tightness and movement.
• Q54: What is Class-4 Fit?
  Ans: Class-4 fit is a snug fit with zero allowance. It gives a close fit without clearance.
• Q55: What is Class-5 Fit?
  Ans: Class-5 fit is a wringing fit with slightly negative allowance. It requires slight force to assemble.
• Q56: What is Class-6 Fit?
  Ans: Class-6 fit is a tight fit with negative allowance. It requires force for assembly.
• Q57: What is Class-7 Fit?
  Ans: Class-7 fit is a medium force fit with moderate negative allowance. It requires considerable force for assembly.
• Q58: What is Class-8 Fit?
  Ans: Class-8 fit is a heavy force fit with maximum negative allowance. It requires high force or special methods for assembly.
• Q59: Convert 4 inches into mm.
  Ans: 1 inch = 25.4 mm
  
  Therefore,
  4 inches = 4 × 25.4
  = 101.6 mm
• Q60: What is meant by Standardization?
  Ans: Standardization is the process of establishing common rules, guidelines, and specifications to ensure uniformity and quality in products and processes.