Understanding Surface Texture in Manufacturing
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Questions and Answers

What does the symbol 'Ra' represent in surface texture indication?

  • Roughness average (correct)
  • Radium average
  • Regular Army
  • Roughness absolute
  • Which of the following is NOT a current method for indicating surface roughness in engineering drawings?

  • Triangle symbols
  • Basic symbol with added bar
  • Three-dimensional CAD representation (correct)
  • Basic symbol with added circle
  • What does the addition of a bar to the basic surface roughness symbol indicate?

  • Removal of material is required (correct)
  • Surface has been treated chemically
  • Surface is exceptionally rough
  • Removal of material is not permitted
  • The worldwide conventions for indicating surface roughness include how many methods?

    <p>128</p> Signup and view all the answers

    What shape is formed by the basic symbol used to indicate surface texture?

    <p>Triangles inclined at 60 degrees</p> Signup and view all the answers

    Where can surface texture requirements be indicated to avoid misinterpretation?

    <p>On dimension lines</p> Signup and view all the answers

    What is required when different surface textures are needed for individual prismatic surfaces?

    <p>Each must be indicated separately</p> Signup and view all the answers

    If surface texture must be defined both before and after treatment, how should this be communicated?

    <p>In an accompanying note</p> Signup and view all the answers

    Where is it permissible to place the surface texture requirement in relation to geometrical tolerances?

    <p>On top of the tolerance frame</p> Signup and view all the answers

    What is a requirement for indicating surface texture on cylindrical features?

    <p>It can only be indicated once using a centerline</p> Signup and view all the answers

    What is required when there are special surface characteristics to indicate?

    <p>Add a line to the longer arm of the symbol</p> Signup and view all the answers

    How should maximum and minimum limits of the principal criterion of surface roughness be represented?

    <p>Both values shall be shown</p> Signup and view all the answers

    What is implied when a circle is added to the complete graphical symbol?

    <p>All surfaces around the workpiece outline require the same texture</p> Signup and view all the answers

    Where should surface texture requirements typically be indicated on technical drawings?

    <p>Once for a given surface in the same view where size or location is shown</p> Signup and view all the answers

    What does the orientation of the graphical symbol and its annotation need to comply with?

    <p>It should be readable from the bottom or right-hand side</p> Signup and view all the answers

    How should the graphical symbol connect to the surface it refers to?

    <p>By a reference/leader line terminating in an arrowhead</p> Signup and view all the answers

    What happens if one particular production method is required for the surface texture?

    <p>It shall be indicated in plain language on an extension of the symbol</p> Signup and view all the answers

    What characterizes the presentation of surface texture requirements on technical documentation?

    <p>They should be indicated clearly and in a connected manner</p> Signup and view all the answers

    Study Notes

    Surface Texture

    • Surface texture encompasses roughness, waviness, lay, and flow
    • Manufacturing processes and part structures affect surface characteristics
    • Multiple methods exist for interpreting surface roughness plots
    • Common methods include:
      • Distance between peak to centerline
      • Average distance between peaks and valleys for sample length
      • Sum of average of first 5 peaks and valleys
      • Maximum peak to valley height
      • Maximum peak height
      • RMS of peak and valley average
    • Variations in surface roughness methods exist worldwide, exceeding 128 conventions
    • Common method is interpreting average roughness (Ra), where R stands for roughness and a for average.
    • Other methods include Rz, Rt, and Rmax
    • Ra (Roughness Average) is the most common indicator of surface roughness and is indicated on technical drawings
    • Surface roughness is now indicated using symbols, superseded the older triangle symbols, though some companies may still use triangle symbols
    • A table correlates Ra values with roughness grades and corresponding symbols
    • Basic symbol for surface texture involves two unequal length lines angled approximately 60 degrees relative to the line representing the surface
    • Thin lines are used for the symbol
    • If machining removes material, an additional bar is added
    • If material removal is not allowed, a circle is added
    • Special surface characteristics can be illustrated using additional lines on the symbols
    • Numerical values defining roughness criteria are added to the symbols, including maximum and minimum limits
    • Production method(s) can be noted on an extension line or other extensions of the symbol
    • Unique methods are indicated when needed
    • Surface texture values are typically specified once per surface, ideally on the same view as size and location of the surface
    • Symbols are oriented for readability (bottom/right side of the drawing)
    • Surface texture requirements can be indicated on dimension lines or tolerance frames; this applies when no risk of misunderstanding is present

    Symbols of Lay

    • Parallel: Symbol is parallel to projection plane of drawing view
    • Perpendicular: Symbol is perpendicular to projection plane of drawing view
    • Crossed: Symbol is crossed in two slant directions relative to projection plane of view
    • Multidirectional: No specific direction, multidirectional
    • Circular: Approximately circular relative to centre of surface
    • Radial: Approximately radial relative to surface centre

    Graphical Symbol for "All Surfaces Around a Workpiece Outline"

    • A circle is added to the complete graphical symbol if all surfaces have the same texture around a work piece outline.
    • The outline represents all surfaces
    • Texture requirements are shown once per surface, in the location where the size or position of the surface is shown
    • Texture specifications are indicated on the same view to minimize confusion

    Positioning and Orientation of Graphical Symbols

    • Symbols and supplementary information should be on the bottom or right side of the drawing
    • Texture requirements are connected to surfaces using reference lines and arrowheads, or placed on extension lines
    • Reference lines point to the relevant surface

    On Dimension Line/Feature-of-Size Dimensions

    • Surface texture requirements can be noted on dimension lines when no risks of misinterpretation are present

    Tolerance Frame for Geometrical Tolerances

    • Surface texture requirements may be noted on tolerance frames

    Cylindrical and Prismatic Surfaces

    • On a cylindrical surface, surface texture info may be placed once on a centerline if all indicated surfaces have the same texture info
    • Distinct texture info is needed on each prismatic surface if there are different textures, as shown in the provided figures
    • All prismatic surfaces must have texture info specified uniquely

    Indication of Two or More Manufacturing Methods

    • Separate note or Figure is included if two or more surface texture specifications are needed (i.e., before and after treatment)

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    Related Documents

    Surface Texture PDF

    Description

    This quiz delves into the various aspects of surface texture, including roughness, waviness, and the different methods used to interpret surface roughness plots. Explore the common metrics such as Ra, Rz, and others, as well as the impact of manufacturing processes on surface characteristics. Test your knowledge on modern conventions and symbols for indicating surface roughness in technical drawings.

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