Podcast
Questions and Answers
What does Maximum Material Condition (MMC) refer to?
What does Maximum Material Condition (MMC) refer to?
- The maximum amount of material within the stated limits of size (correct)
- The average size of a feature
- A condition where the material is evenly distributed
- The minimum size of a feature
Every feature control frame must contain a reference datum.
Every feature control frame must contain a reference datum.
False (B)
What problem arises with the angularity of a tolerance zone?
What problem arises with the angularity of a tolerance zone?
The zone is wedge-shaped, allowing more tolerance at one end than the other.
The ______ controls the axis-to-axis relationship between two features.
The ______ controls the axis-to-axis relationship between two features.
Match the following tolerancing concepts with their definitions:
Match the following tolerancing concepts with their definitions:
What system do most drawings conform to?
What system do most drawings conform to?
A zero must always be placed before the decimal point for values less than one inch.
A zero must always be placed before the decimal point for values less than one inch.
Where do notes typically appear on a drawing?
Where do notes typically appear on a drawing?
When dimensioning a visible gap, there should be at least ___ ___ between extension lines and object geometry.
When dimensioning a visible gap, there should be at least ___ ___ between extension lines and object geometry.
Match the following symbols with their meanings:
Match the following symbols with their meanings:
What is the minimum distance dimension lines should be from any view?
What is the minimum distance dimension lines should be from any view?
A dimension specified for a given feature on one level of drawing is mandatory for that feature at any other level.
A dimension specified for a given feature on one level of drawing is mandatory for that feature at any other level.
All dimensions and tolerances apply in a _____ _____ condition.
All dimensions and tolerances apply in a _____ _____ condition.
What is the purpose of baseline dimensioning?
What is the purpose of baseline dimensioning?
Tolerances specify the total permissible variation in a dimension.
Tolerances specify the total permissible variation in a dimension.
What does ASME stand for?
What does ASME stand for?
A loose running fit is used for __________ commercial tolerances or allowances on external members.
A loose running fit is used for __________ commercial tolerances or allowances on external members.
Match the following types of fits with their descriptions:
Match the following types of fits with their descriptions:
What is the consequence of using chain dimensioning?
What is the consequence of using chain dimensioning?
A dimension should appear multiple times in different views on a drawing.
A dimension should appear multiple times in different views on a drawing.
What does a line with an arrow pointing down on a drawing indicate?
What does a line with an arrow pointing down on a drawing indicate?
Form tolerances are concerned with individual features and are not related to __________.
Form tolerances are concerned with individual features and are not related to __________.
Which tolerancing method is most frequently used?
Which tolerancing method is most frequently used?
Dimensions and tolerances apply only at the drawing level where they are specified.
Dimensions and tolerances apply only at the drawing level where they are specified.
How many decimal places should a dimension have based on its tolerance?
How many decimal places should a dimension have based on its tolerance?
The feature control frame contains the geometric characteristic symbol, the geometric tolerance, and the relative __________.
The feature control frame contains the geometric characteristic symbol, the geometric tolerance, and the relative __________.
What does the nomenclature 'TYP' signify in engineering drawings?
What does the nomenclature 'TYP' signify in engineering drawings?
A unilateral tolerance allows deviations in both directions from the basic size.
A unilateral tolerance allows deviations in both directions from the basic size.
Direct dimensioning yields the ______ accumulation of tolerances.
Direct dimensioning yields the ______ accumulation of tolerances.
What is statistical tolerancing?
What is statistical tolerancing?
Which type of fit always ensures space exists between mating parts?
Which type of fit always ensures space exists between mating parts?
Match the types of fits with their descriptions:
Match the types of fits with their descriptions:
For metric dimensions, a plus or minus sign is always shown.
For metric dimensions, a plus or minus sign is always shown.
Describe what the primary datum plane is established by.
Describe what the primary datum plane is established by.
The difference between the maximum material limits of mating parts is referred to as ______.
The difference between the maximum material limits of mating parts is referred to as ______.
What does '3 mil' plastic sheet stock refer to?
What does '3 mil' plastic sheet stock refer to?
Errors related to GD&T stem from how the datum reference frame was established.
Errors related to GD&T stem from how the datum reference frame was established.
What happens when the designer does not pay attention to dimensioning?
What happens when the designer does not pay attention to dimensioning?
A locational interference fit is designed for parts that require ______.
A locational interference fit is designed for parts that require ______.
Which fit requires the tightest fit usable with cast iron?
Which fit requires the tightest fit usable with cast iron?
What is the shape of the tolerance zone for angularity?
What is the shape of the tolerance zone for angularity?
What happens when tolerances are applied that are too large or too loose?
What happens when tolerances are applied that are too large or too loose?
What does the profile tolerance control when datums are specified?
What does the profile tolerance control when datums are specified?
Which of the following tolerances does NOT require a reference datum?
Which of the following tolerances does NOT require a reference datum?
Which statement accurately describes the use of basic dimensions in engineering drawings?
Which statement accurately describes the use of basic dimensions in engineering drawings?
In chain dimensioning, how are features dimensioned?
In chain dimensioning, how are features dimensioned?
When dimensioning a gap, what is the minimum space that should be maintained between extension lines and object geometry?
When dimensioning a gap, what is the minimum space that should be maintained between extension lines and object geometry?
What is the preferred distance that dimension lines should be from any view in a drawing?
What is the preferred distance that dimension lines should be from any view in a drawing?
Which of the following systems do most engineering drawings conform to?
Which of the following systems do most engineering drawings conform to?
What is indicated by the symbol '|' in a drawing?
What is indicated by the symbol '|' in a drawing?
Which statement is true regarding the use of zeros before decimal points in dimensions?
Which statement is true regarding the use of zeros before decimal points in dimensions?
What is the reasoning behind applying dimensions in a free state condition?
What is the reasoning behind applying dimensions in a free state condition?
Baseline dimensioning helps in eliminating what aspect related to tolerances?
Baseline dimensioning helps in eliminating what aspect related to tolerances?
What type of fits allow for a small amount of clearance or interference?
What type of fits allow for a small amount of clearance or interference?
Which of the following tolerances controls the orientation of a surface or axis relative to a datum?
Which of the following tolerances controls the orientation of a surface or axis relative to a datum?
What framework contains the geometric characteristic symbol, the geometric tolerance, and the relative datums?
What framework contains the geometric characteristic symbol, the geometric tolerance, and the relative datums?
Which fits are characterized by maintained constant bore pressures throughout a range of sizes?
Which fits are characterized by maintained constant bore pressures throughout a range of sizes?
Which type of fits is not intended to run freely but should allow accurate movement and location?
Which type of fits is not intended to run freely but should allow accurate movement and location?
What does the angulated tolerance control in relation to a datum?
What does the angulated tolerance control in relation to a datum?
What should dimensions on a drawing primarily indicate?
What should dimensions on a drawing primarily indicate?
What does unilateral tolerance imply about deviation from the basic size?
What does unilateral tolerance imply about deviation from the basic size?
What type of fit is best for high running speeds and large temperature variations?
What type of fit is best for high running speeds and large temperature variations?
Which of the following is true regarding baseline dimensioning?
Which of the following is true regarding baseline dimensioning?
Which type of fit is specified to ensure that an interference will always exist between mating parts?
Which type of fit is specified to ensure that an interference will always exist between mating parts?
Clearance fits are characterized by which of the following descriptions?
Clearance fits are characterized by which of the following descriptions?
What indicates the diameter when dimensioning circles?
What indicates the diameter when dimensioning circles?
What is the primary purpose of statistical tolerancing?
What is the primary purpose of statistical tolerancing?
What should be the main basis for the number of decimal places in a dimension?
What should be the main basis for the number of decimal places in a dimension?
What is the maximum allowable variation in dimensions referred to as?
What is the maximum allowable variation in dimensions referred to as?
When dimensioning a part, which of the following is a best practice concerning hole features?
When dimensioning a part, which of the following is a best practice concerning hole features?
Which fits are primarily used when accurate location is important?
Which fits are primarily used when accurate location is important?
What does the nomenclature 'TYP' or 'TYPICAL OF' indicate in engineering drawings?
What does the nomenclature 'TYP' or 'TYPICAL OF' indicate in engineering drawings?
For metric dimensions, how is a single zero represented?
For metric dimensions, how is a single zero represented?
Which category of fits is known for ensuring accurate location while allowing both clearance and interference?
Which category of fits is known for ensuring accurate location while allowing both clearance and interference?
When dimensioning in inches, how is the tolerance value typically expressed?
When dimensioning in inches, how is the tolerance value typically expressed?
What is the difference known as between the maximum material limits of mating parts?
What is the difference known as between the maximum material limits of mating parts?
Which fit is characterized by tight assembly and is practical for materials that can be highly stressed?
Which fit is characterized by tight assembly and is practical for materials that can be highly stressed?
What is the purpose of GD&T in engineering drawings?
What is the purpose of GD&T in engineering drawings?
What is a key consideration for establishing the primary datum plane?
What is a key consideration for establishing the primary datum plane?
What should be done first when determining an English fit for a design?
What should be done first when determining an English fit for a design?
Flashcards
Total Runout
Total Runout
The total amount of variation in a part's position when it rotates around an axis.
3D Control
3D Control
Controlling the shape and position of rotating parts using datums (specified reference points).
Basic Dimensions
Basic Dimensions
Dimensions that precisely locate features on a part, theoretically perfect.
Dimensioning Systems
Dimensioning Systems
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Dimensioning MM less than 1mm
Dimensioning MM less than 1mm
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Dimensioning MM whole mm
Dimensioning MM whole mm
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Dimensioning Tolerances
Dimensioning Tolerances
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Chain Dimensioning
Chain Dimensioning
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Maximum Material Condition (MMC)
Maximum Material Condition (MMC)
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Perpendicularity Tolerance
Perpendicularity Tolerance
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Concentricity Tolerance
Concentricity Tolerance
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Circular Runout
Circular Runout
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Tight Tolerances Cost
Tight Tolerances Cost
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Baseline dimensioning
Baseline dimensioning
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Tolerance
Tolerance
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Feature control frame
Feature control frame
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Form tolerances
Form tolerances
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Position tolerance
Position tolerance
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Profile tolerance
Profile tolerance
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Parallelism tolerance
Parallelism tolerance
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Angularity tolerance
Angularity tolerance
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Inspection methods
Inspection methods
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Transition fit
Transition fit
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Force/Shrink Fit
Force/Shrink Fit
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Loose Running Fit
Loose Running Fit
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Cylindrical Feature Dimensioning
Cylindrical Feature Dimensioning
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Repeated Features (TYP)
Repeated Features (TYP)
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Dimension Assumptions (Temperature & Pressure)
Dimension Assumptions (Temperature & Pressure)
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Unilateral Tolerance
Unilateral Tolerance
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Metric Dimensions (Zero Tolerance)
Metric Dimensions (Zero Tolerance)
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English Tolerance Decimal Places
English Tolerance Decimal Places
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Limit Dimensions
Limit Dimensions
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Direct Dimensioning
Direct Dimensioning
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Statistical Tolerancing
Statistical Tolerancing
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Statistical Tolerancing Problem
Statistical Tolerancing Problem
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Clearance Fit
Clearance Fit
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Interference Fit
Interference Fit
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Selective Assembly
Selective Assembly
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Dimension Line Spacing
Dimension Line Spacing
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Dimensioning Gaps
Dimensioning Gaps
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Free State Condition
Free State Condition
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Tertiary Datum Plane
Tertiary Datum Plane
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Plus/Minus Tolerancing
Plus/Minus Tolerancing
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Dimensioning to Visible or Solid Lines
Dimensioning to Visible or Solid Lines
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Contour Rule/Contour Dimensioning
Contour Rule/Contour Dimensioning
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Dimensioning Holes
Dimensioning Holes
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Dimensioning Cylinders
Dimensioning Cylinders
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"TYP" or "TYPICAL OF"
"TYP" or "TYPICAL OF"
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Dimension Assumptions
Dimension Assumptions
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Metric Zero Tolerance
Metric Zero Tolerance
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Problem with Statistical Tolerancing
Problem with Statistical Tolerancing
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Study Notes
Dimensioning and Tolerancing Fundamentals
- Metric vs. US Customary: Drawings use either the SI (metric) or US Customary system.
- Decimal Representation (mm): Dimensions less than 1 mm use a zero before the decimal; whole millimeters omit the decimal and zero; decimals greater than 1 but less than 2 mm show the non-zero decimal digit.
- Decimal Representation (inches): A zero is not used before the decimal for values less than 1 inch.
- Dimension Placement: Dimension lines should be a minimum 10 mm from any view; 6 mm clearance between dimension lines if placed outside other dimensions. At least 1 mm should be between extension lines and object geometry. Dimension lines extend 2–3 mm past the extension lines.
- Datum References: Basic dimensions, boxed dimensions, denote theoretically exact feature locations from clearly defined datums.
- Dimensioning Holes/Features: Dimensioning holes from the part end is preferred over dimensioning between holes.
- Dimensioning Techniques:
- Chain Dimensioning: Dimensioning features relative to each other (used in situations needing feature relationships).
- Baseline Dimensioning: Dimensions originate from a common datum to eliminate tolerance accumulation (preferred over chain dimensioning).
- Dimensioning Location: Dimension only to visible or solid lines.
- Geometric Tolerancing:
- Form Tolerances: Control the shape/geometry of individual features (straightness, flatness, circularity, cylindricity).
- Profile Tolerances: Define a 2D tolerance zone by two contours (controls shape and size/location of contour). Methods exist for inspecting profile tolerances such as optical comparitors and mechanical gaging.
- Orientation Tolerances: (parallelism, perpendicularity, angularity) Control the orientation of a surface or axis relative to datum.
- Position Tolerances: Controls the orientation and location of a feature (center, axis, plane) in relation to datum/datums. These are 3D tolerance zones.
- Symmetry Tolerances: Similar to concentricity, but related to the position of a center plane relative to an axis or datum (harder to inspect).
- Circular Runout: 2D control; surface relative to a datum axis.
- Tolerance Types:
- Bilateral Tolerances: Deviation equally distributed above and below the basic size.
- Unilateral Tolerances: Deviation in one direction only (above or below).
- Limit Dimensions: High and low limit tolerances displayed above and below.
- Statistical Tolerancing: Using statistical methods to assign tolerances based on processes. Has a disadvantage of potentially resulting in more restrictive tolerances.
- Clearance Fits: Space exists between mating parts.
- Interference Fits: Interference exists between mating parts.
- Transition Fits: Either a clearance or interference fit may result.
- Allowance: Difference in maximum material limits between mating parts.
- Basic Size: Size from which limit dimensions are derived.
- Hole Basis (Basic Hole System): Basic size is applied to lower limit of the hole.
- Shaft Basis (Basic Shaft System): Basic size applied to upper limit of the shaft.
- Fits:
- English Fits: (RC, LC, LT, LN, FN). Follow specific procedures to determine tolerances per drawing.
- Metric Fits: Includes fits for loose running, free running, close running, sliding. Locational clearance, locational transition, locational interference. Fit types for drive (medium drive) and force fit. Follow similar procedures as English Fits.
- GD&T (Geometric Dimensioning and Tolerancing) Advantages: Allows designers to clearly specify design intent, improve communication, and reduce misinterpretation.
- Datum Reference Frames: Required for GD&T (datums create references for the feature control frame features)
- Application Considerations: Tolerances that are too small/tight result in increased manufacturing difficulty and cost. Tolerances that are too large/loose may result in malfunctioning parts.
- Feature Control Frame: Contains geometric characteristic symbol, geometric tolerance, and relative datums.
- Other Notes: Tolerances are applied in a free state in an engineering drawing; dimensions have assumed room temperature and pressure contexts; dimensions shall appear only once on a drawing unless otherwise specified; if a dimension has a tolerance, every single dimension must show a tolerance.
- Dimensioning Practices: Circular features are typically dimensioned as diameters; arcs are usually dimensioned as radii.
Special Feature Types
- Chamfers: Dimensioned with length from end and angle or two distances.
- Depth: Represented by a line with a down-pointing arrow.
- Gage/Code Materials: Specified by linear dimensions (diameter or thickness).
- 90° Angles: Implied where centerlines and feature lines are at right angles (basic dimensioning).
- Maximum Material Condition (MMC): Feature of size with the maximum amount of material within stated size limits.
Additional Details
- Geometric Characteristics: Include terms like straightness, flatness, parallelism, perpendicularity, angularity, circularity, cylindricity, concentricity, position, symmetry, profile.
- Conventional Tolerancing: Controls size only.
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