Radiation Heat Transfer

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View Factor Orientation (or View factor or shape factor) plays an important role in radiation heat transfer. View factor is defined as, "fraction of radiation leaving surface 'i' and strike 'j' ". Summation Rule (View Factor) If there is are similar surfaces 'i' and 'j' , then: Blackbody Radiation Exchange Radiation Exchange between Opaque, Diffuse, Gray surfaces in an Enclosure 1. Opaque 2. Surfaces 3. Two surface enclosure Radiation Shield It is used to protect surfaces from radiation act like a reflective surface. References: Material from Class Lectures + Book named Fundamentals of Heat and Mass Transfer by Theodore L. Bergman + My knowledge.  Photoshoped pics  are developed.  Some pics and GIF from Google.   Videos from YouTube ( Engineering Sights ).
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Gear Forming by Machining

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Gear Forming by Machining

Formation of gear through machining consists of following methods:
      1. Form Milling by Disc Cutter
      2. Form Milling by End Mill Cutter
      3. Shaper, Planner and Slotter
      4. Broaching

1. Form Milling by Disc Cutter

It is defined as, "Tooth is cut one by one by plunging the rotating cutter into the blank". 
  • Each gear needs a separate cutter.
  • 8 - 10 standard cutters are available for producing 12 - 120 teeth gears.
  • Used for big spur gears of large pitch.

2. Form Milling by End Mill Cutter

It includes the cutting of tooth at a time and then indexed for the next tooth space for cutting.
  • For a small volume production of low precision gears.
  • Set of 10 cutters  ↠  12 - 120 teeth gears.
  • Used for teeth of large gears/module.
  • To reduce cost, same cutter is often used for multiple sized gears resulting in profile errors.

Characteristics:

  1. Use of Hardened stainless steels (HSS) form milling cutters.
  2. Use of Ordinary milling machines.
  3. Low production rate (need of indexing after machining, slow speed and feed).
  4. Gear having different modules and number of teeth need separate milling cutters.
  5. Low Accuracy and surface finish.

3. Shaping, Planning & Slotting of Tooth Space

  • Shaper  ↠  Linear motion for cutting reciprocates parallel to the center axis of blank and cuts one tooth at a time. It is used for repair and maintenance purpose.
  • Planning  ↠  Machine for large gears.
  • Slotting  ↠  for internal gears.

4. Broaching

Multi-toothed tool in which successive tooth takes a small cut but when all the teeth have passed over the gear blank to be machined.
  • Internal, external spur gears, straight or single helical gears are produced in large quantity.
  • External teeth are produced by broaching in one pass.
Note:

References:

  • Material from Class Lectures + Book named Fundamentals of Modern Manufacturing Materials, Processes and Systems by Groover + My knowledge. 
  • Photoshoped pics are developed. 
  • Some pics and GIF from Google.  
  • Videos from YouTube (Engineering Sights).

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