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Questions and Answers
What is the primary requirement for linear measurement instruments in modern industry?
What affects the accuracy of readings captured from line-graduated instruments?
Why is it necessary to provide compensation against wear in instruments with a scale?
What can attachments contribute to in linear measurement instruments?
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What is the fundamental principle of good design in linear measurement instruments?
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What is the primary factor that ensures accuracy in instruments such as callipers?
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What is the advantage of dial versions of linear measurement instruments?
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Why is proper training necessary for users of linear measurement instruments?
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What is one factor that influences readability, apart from resolution?
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What should be incorporated into a comparator to compensate for?
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What is a characteristic of a mechanical comparator?
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What is the primary use of a dial indicator?
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What is the function of the bezel clamp in a dial indicator?
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What is the range of linear measurements that a dial indicator can measure?
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What is a characteristic of a balanced dial in a dial indicator?
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What is the purpose of a comparator?
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What does a comparator measure?
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What is the characteristic of a comparison measurement?
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What is the main advantage of electrical comparators?
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What is the purpose of a Wheatstone bridge circuit in electrical comparators?
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What is the function of a linear variable differential transformer (LVDT) in electrical comparators?
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What is the principle involved in pneumatic comparators?
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What is the advantage of pneumatic comparators due to the absence of metal-to-metal contact?
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What is the range of measurement for pneumatic comparators?
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What is a crucial aspect of an instrument's reliability?
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What is the primary advantage of digital instruments over mechanical ones?
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What is the purpose of a ratchet stop in a measuring instrument?
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What is a key characteristic of a comparator's scale?
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What is the primary advantage of comparison measurement over direct measurement?
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What is a comparator's resolution?
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Why do micrometers have a better least count than vernier scales?
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What is the main challenge in designing a comparator?
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What type of pneumatic gauge is more commonly used?
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What is the purpose of thread measurement in manufacturing and engineering?
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What is the largest diameter of the external or internal thread?
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What type of fit is characterized by a gap between the mating parts?
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What is the purpose of the 'Go' gauge in thread measurement?
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What is the name of the international standard for thread fit?
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What is a potential source of error in thread measurement?
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What type of machine can measure the exact geometry of the thread in three dimensions?
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Study Notes
Linear Measurement Instruments
- Designed to meet high demands of accuracy and precision, while being simple to operate and cost-effective
- Important considerations for design:
- Measuring accuracy depends on the original accuracy of line graduations
- Instruments with scales require compensation against wear
- Attachments can enhance versatility but also contribute to accumulated error
- User skill is essential for accurate measurements
- Principle of alignment: line of measurement and line of dimension being measured should be coincident
- Electronic versions provide convenience, but basic principles must be adhered to
- Readability is crucial, and instruments with better readability are more reliable
- Digital instruments offer ease of signal processing and direct expression of readings in required form
Comparators
- Must provide high accuracy and precision, convenience, and withstand rough operating environments
- Major requirements:
- High accuracy and precision
- Linear scale with a wide range
- High amplification
- Good resolution
- Provision for temperature compensation
- Versatility with attachments and flexible means
- Classification of comparators:
- Mechanical comparators
- Mechanical-optical comparators
- Electrical and electronic comparators
- Pneumatic comparators
- Other types (projection, multi-check)
Mechanical Comparators
- Provide simple and cost-effective solutions
- Skills for fabrication and use can be learned relatively easily
- Important comparators in metrology:
- Dial Indicator: used to compare workpieces against a master, with interchangeable contact points and a scale that provides the required least count
Electrical Comparators
- Use electrical signals for measurement
- Main elements:
- Plunger (sensing element)
- Armature
- Coils
- Output display device
- Can achieve high magnification (up to 10^5:1)
Pneumatic Comparators
- Use air as a means of measurement
- Basic principle: changes in calibrated flow respond to changes in part feature
- Advantages:
- Absence of metal-to-metal contact
- Higher amplification
- Low cost
- Can be used for inspecting multiple dimensions of a part in a single setting
Thread Measurement
- Screw thread limits define the acceptable range of thread dimensions
- Key parameters:
- Major Diameter
- Minor Diameter
- Pitch Diameter
- Lead
- Pitch
- Fit limits determine how tightly or loosely the threaded parts will fit together
- Tolerance classes:
- Unified Thread Standard (UTS)
- ISO Metric Thread
- Gauging methods:
- Go/No-Go Gauges
- Thread Micrometers
- Optical Comparators
- Coordinate Measuring Machines (CMM)
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Description
This quiz assesses your understanding of linear measurement instruments used in modern industry, including their accuracy, design, and attachments. Learn about the importance of wear compensation and the principles of good design.
