SURFACE SYMBOLS

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Lesson 9

• ?? ???
• SURFACE SYMBOLS

• What for surface symbols
• Types of surface
• Surface Texture
• Surface Roughness
• Finishing Symbols

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WHAT FOR SURFACE SYMBOLS?

• In preparing working drawings or parts to be cast
  or forged, the draftman must indicate the
  surfaces on the drawing which require machining
  or finishing. 
• Need surface
  symbols

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TYPES OF SURFACES

• Working surfaces
•  Bearings, pistons, and gears
•   require surface control
• Nonworking surfaces
• Walls of transmission cases, crankcases, or
  differential housings.
• Seldom require any surface control

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SURFACE TEXTURE

• Repetitive and/or random deviations from the
  nominal surface
• Four Elements
• (1) Roughness(???)
• Small, finely spaced deviations from the nominal
  surface.
• Determined by the material characteristics and
  the process that formed the surface.
• (2) Waviness(??)
• deviations of much larger spacing
• Due to work deflection, vibration, heat
  treatment, and similar factors Working surfaces

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SURFACE TEXTURE

• (3) Lay
• Predominant direction or pattern of the surface
  texture
•  Determined by the manufacturing method used to
  create the surface, usually from the action of a
  cutting tool.

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SURFACE TEXTURE

• Lay Symbol

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SURFACE TEXTURE

• (4)  Flaw
• Irregularities that occur occasionally on the
  surface.
• cracks, scratcheds, inclusions, similar defects
  in the surface.

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SURFACE ROUGHNESS

• Ra ??? ?? ??? ???
• ???? ???? ?? ?? ???
• Rmax ???? ??? ???
• Rz ?? ?? ??? ???

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SURFACE ROUGHNESS

• Ra (??? ?? ??? ???)

• ??? ????? ????? ??? ?????? ???? ??? ????? ????
  ???? Ra ????? ??? ??

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SURFACE ROUGHNESS

• Ra (??? ?? ??? ???)

• ??? ???? ???? L?? ?????, ? ??? ??? ?? yf(x)?
  ????? ? ??? ??? ???? ??? ?? ???? ??

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SURFACE ROUGHNESS

• Ra (??? ?? ??? ???)

• 1.6a ? ?? ?????? Ra ???? ?????? ???? ??? ????
  1.6 ? ??? ??? ?? ??
• 0.013, 0.025, 0.05, 0.1, 0.2, 0.4 0.8, 1.6, 3.2,
  6.3, 12.5, 25, 50, 100 ?? ??
• ????? ??? ?? 3? ?? ???? ???
• 12.5 ??? 0.8mm ????, 25-100 ? 2.5mm ????? ???? ?.

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SURFACE ROUGHNESS

• Ra (??? ?? ??? ???)

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SURFACE ROUGHNESS

• Rmax, Rs (???? ??? ???)

• ?????? ???? L?? ???? ??? ???? ???, ? ???? ?????,
  ????? ??? ?? ??? ?? ??? 2?? ??? ??, ? ??? ??
  Rmax? ?? ???? ???.
• Rmax? ??? ????? ?? ???? ????? ??????? ???.

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SURFACE ROUGHNESS

• Rmax, Rs (???? ??? ???)

• 1.6s ? ?? ?????? Rmax???? ?????? ???? ??? ????
  1.6 ? ??? ??? ?? ??
• 0.05, 0.1, 0.2, 0.4 0.8, 1.6, 3.2, 6.3, 12.5, 25,
  50, 100,400 ?? ??
• ????? ??? ? ??? ??

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SURFACE ROUGHNESS

• Rz (?? ?? ??? ???)

• ?????? ???? L?? ???? ??? ???? ???, ??? ??? ?? ??
  ??? ?? ?? 5?? ??? ??? ???? ?? ?? ??? ?? ?? 5??
  ??? ????.
• ?? ?? 5?? ??? ???????? ???? ??? S? ???.
• ?? ?? 5?? ??? ???????? ???? ??? V? ???.
• S? V? ????? ???? ????

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SURFACE ROUGHNESS

• Ra ?? Rmax? Rz ?? ¼ ???, ????, Ra?? ???? ???? ??
  ????? ???? ??, Rmax, Rz? ???? ??? ???? ??? ?? ???
  ????.

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FINISHING SYMBOLS

• Symbols
• Types
• Examples
• Placing
• Direction

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FINISHING SYMBOLS
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FINISHING SYMBOLS
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FINISHING SYMBOLS
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FINISHING SYMBOLS
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FINISHING SYMBOLS