Specifying the Perfect Encoder: How to Avoid the Most Common Encoder Errors
 

Specifying the Perfect Encoder: How to Avoid the Most Common Encoder Errors

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Join us during this webinar as Encoder Products and US Digital discuss ways to avoid the most common errors when specifying encoders. Topics covered will include how knowing the difference between ...

Join us during this webinar as Encoder Products and US Digital discuss ways to avoid the most common errors when specifying encoders. Topics covered will include how knowing the difference between position accuracy and resolution aides in selecting the right encoder, as well as important mechanical, electrical, and environmental considerations.

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Specifying the Perfect Encoder: How to Avoid the Most Common Encoder Errors Specifying the Perfect Encoder: How to Avoid the Most Common Encoder Errors Presentation Transcript

  • Specifying the Perfect Encoder: How to Avoid the Most Common Encoder Errors
  • Sponsored By:
  • Before We Start q  This webinar will be available afterwards at designworldonline.com & via email q  Q&A at the end of the presentation q  Hashtag for this webinar: #DWwebinar
  • Presenter Moderator Miles Budimir Design World Jim Stevens Dan Craner US Digital Encoder Products
  • EPC ENCODER SOLUTIONS THAT JUST MAKE SENSE
  • ABOUT EPC •  •  •  Global designer and manufacturer of industrial incremental and absolute rotary encoders Established 1969 100,000 sq ft. facility in Sagle, Idaho 7
  • THE CHALLENGE 725i-S-S-1024-R-HV-1-F-1-SX-N-N HA52510240341 XH25D-SS-1024-ABZC-28V/V-SM18 8
  • CRITICAL CONSIDERATIONS •  •  •  •  Package Style Mechanical Electrical Environmental
  • PACKAGE STYLES
  • TWO TYPES Bore Shaft
  • PACKAGE STYLE SELECTION: BORE Avoid specifying a shaft encoder when a through-bore will be the better choice. - Incurred additional hardware cost - Installation - Cost of ownership/operation– belts, pulleys, chains, sprockets too tight - Shaft couplings, set screws
  • PACKAGE STYLE SELECTION: SHAFT In some applications the shaft style is preferred: MOBILE / OUTDOOR WASHDOWN SEVERE CONDITIONS
  • SEALING SHAFT VS. BORE Maintaining seal integrity of a 3/8” shaft is much more certain than a ¾” bore
  • PACKAGE STYLE: SHAFT LOADS Hollow bore or through-bore devices are not commonly designed for shaft loads, but mount free floating with a flexible anti-rotation tether. Shaft encoders are designed for heavy radial/axial shaft loading - Measuring wheel applications - Axial / radial loads
  • MECHANICAL SPECIFICATION: BEARINGS Confirm bearings are adequate for operational axial/radial loads. - Peak loads - Shock Vs. 5lbs axial/radial 80lbs axial/radial
  • MECHANICAL SPECIFICATION: BEARINGS
  • WE GET SUSPICIOUS WHEN… “The encoder was bad out of the box.” “All the wiring checks out.” “Everything is fine until I get these intermittent missed counts…and sometimes extra counts.” “I sent the encoder back for repair and it checks out OK. I’m still having problems.” “It worked perfectly on the test bench, but when installed…”
  • COMMON PROBLEM: SIGNAL NOISE Be sure to sufficiently account for electrical noise Preferred output type: Differential Line Driver -  Complementary signals -  Error checking
  • COMMON PROBLEM: SIGNAL NOISE Cable specifications -  Shielded cable -  Twisted Pair Cable routing Termination practices
  • ENVIRONMENTAL CONSIDERATIONS A word about IP ratings….
  • ENVIRONMENTAL CONSIDERATIONS
  • 3 PATHWAYS OF INGRESS Connector Shaft Seal Case/Hub interface
  • IP RATINGS - Specify an appropriate IP rating for all operating conditions - Consider all ingress pathways: shaft/bore, housing, connector - Understand the IP Ratings Standard - Understand the manufacturer specifications Shaft seals: more is not always better - break away torque - heat generator
  • EPC ENCODER SOLUTIONS THAT JUST MAKE SENSE
  • The  Truth  Behind  Kit   Encoder  Position  Accuracy  
  • Introductions  –  Who  Are  We?   §  Presenter:  Jim  Stevens,  VP  of  Sales  and   Marketing  at  US  Digital   §  US  Digital  is  a  US-­‐based  manufacturer  of   Motion  Control  Products  in  Vancouver,   Washington  for  over  30  years.  
  • Today  we  will  talk  about  the   positional  accuracy  of  a  kit  or   modular  style  encoder.  
  • Positional  Accuracy  Misconceptions   §  Accuracy  is  cumulative  with  every  rotation  of   the  encoder  disk.   §  Accuracy  is  a  function  of  disk  to  sensor  gap   spacing.   §  Calculating  encoder  accuracy  is  nearly   impossible.  
  • OR  is  “Optical   Radius”  
  • Optical  Detector  
  • Shaft   Optical  Detector  
  • Set  Screw   Hubdisk   Shaft   Optical  Detector  
  • Set  Screw   This  distance   indicates  “optical   radius”.   Hubdisk   Shaft   Optical  Detector  
  • TIR  is  “Total   Indicated  Runout”  
  • Perfectly  centered   disk.  No  disk  error.   Disk  Error  (none)   An  example  of  a  disk  with  a  perfect  center  rotating  correctly.  
  • Disk  not  perfectly   centered  can   cause  disk  errors   Disk  Error  (offset)   Disk  off  center  rotating  incorrectly.   Disk  not  perfectly   centered  affects   accuracy  
  • (TIR)  Hubdisk  and  Shaft  Formula   How  set  screw  can  affect  centering  and  accuracy.  
  • Notice  set  screw.  
  • Set  screw  tightened.   Hubdisk  no  longer   centered.   Hubdisk  and  Set  Screw   How  set  screw  can  affect  centering  and  accuracy.   Disk  not  perfectly   centered  affects   accuracy  
  • Arc  min.   Error   Shaft  L  
  • If  OR  =  0.433”   Disk  Error  =  0.001”   Shaft  ø  =  0.2498”   Hub  ø  =  0.2501”   to  0.2506”   A  Sample  Calculation  
  • Solving  TIR  
  • Completing  the  Equation  
  • Arc  min.   14.3   180º   360º   Shaft  L    
  • Thank  You!  
  • Questions? Design World Miles Budimir mbudimir@wtwhmedia.com Phone: 440.234.4531 Twitter: @DW_Motion US Digital Jim Stevens Jim.s@usdigital.com Phone: 360-260-2468 Twitter: @USDigital Encoder Products Dan Craner danc@encoder.com Phone: 208-255-4700
  • Thank You q  This webinar will be available at designworldonline.com & via email q  Tweet with hashtag #DWwebinar q  Connect with q  Twitter: @DesignWorld q  Facebook: facebook.com/engineeringexchange q  LinkedIn: Design World Group q  YouTube: youtube.com/designworldvideo q  Discuss this on EngineeringExchange.com