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Temperature compensation for precision gaging


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Paul Sagar, President of Albion Devices Inc., explains the importance of temperature compensation for precision gaging in critical parts manufacturing.

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Temperature compensation for precision gaging

  1. 1. From<br />Albion Devices, Inc.<br /><br />Presented by<br />Paul Sagar<br />President<br />Temperature Compensationof Shop Floor Gages<br />
  2. 2. About Albion<br />Albion Devices, Inc., was founded in 1988.<br />Albion was first to make a concerted effort to address the problem of thermal expansion as it affects shop floor gages<br />We have developed many products, software programs and custom sensors for temperature compensation applications.<br />We have had hundreds of successful applications.<br />Customers include all Big Three auto companies, major railroads, GE, bearing companies (SKF), printers, auto industry suppliers, etc.<br />Albion Devices, Inc.<br />
  3. 3. Why Compensate for Temperature? <br />Albion Devices, Inc.<br />Because variations in temperature during the production process cause measurement errors.<br />Particularly when close to tolerance limits.<br />Correction improves customer acceptance, product performance and correlation.<br />60 measurements taken of the same feature on the same part on the same shop floor gage over a period of 2 weeks. Measurements varied by approx. 100% of tolerance due almost entirely to varying ambient temperatures.<br />
  4. 4. Benefits of Eliminating Thermal Errors<br /> Consistent Accuracy (rather than precision)<br /> Maintains Gage R&R on shop floor.<br /> Gives Dimension at the International Standard 68F / 20C, (or other specified nominal temperature).<br />Albion Devices, Inc.<br />
  5. 5. Product History<br />Snap gages<br />Tcomp (“tee-comp”)<br />GageComp<br />Sensors<br />MicroComp<br />Tcomp II<br />Albion Devices, Inc.<br />
  6. 6. Latest Development<br />Fireball Digital Temperature Sensors (and Measurement Probes).<br />DigiGage software.<br />Albion Devices, Inc.<br />
  7. 7. Applications<br />Albion’s systems have been used to compensate a wide range of gages.<br />Albion Devices, Inc.<br />
  8. 8. Temperature Compensation System Components<br />Albion Devices, Inc.<br />Combined Workpiece/Master Temperature Sensor, for OD or ID.<br />Gage Temperature Sensor.<br />Connecting cables.<br />Controller or PC.<br />
  9. 9. Sensor Configuration<br />Workpiece sensor positioned to pick up temperature of workpiece and master.<br />Gage sensor monitors temperature of fixture or gage.<br />For Temp Comp to be most effective, best to MINIMIZE contact between gage and workpiece.<br />Albion Devices, Inc.<br />LVDT<br />Workpiece/<br />master<br />sensor<br />Workpiece<br />Gage Fixture<br />Gage<br />sensor<br />Note minimal contact<br />
  10. 10. Applied Principles<br />Compensate for Work, Master and Gage.<br />Note: Gage, not ambient.<br />Sense each temperature independently.<br />Customizable coefficients of correction.<br />Nominal size.<br />Workpiece<br />Temperature<br />Master<br />Temperature<br />Gage<br />Temperature<br />Workpiece<br />Coefficient<br />Master<br />Coefficient<br />Gage<br />Coefficient<br />Compensation<br />Algorithm<br />Nominal<br />size<br />Correction<br />Offset<br />Albion Devices, Inc.<br />
  11. 11. Linearity<br />Albion Devices, Inc.<br />Coefficients of Expansion are often non-linear over large temperature ranges.<br />However, materials used in mass produced items are linear over the temperature range that concerns us.<br />F<br />F<br />
  12. 12. Correction Coefficients<br />Practically speaking, strict handbook COEs are not necessarily the most accurate.<br />Several factors influence the way sizes vary with temperature (e.g. combinations of materials and geometries, thermal gradients, joints, springs).<br />Albion refers to the net effect of these influences as the Correction Coefficient.<br />One way to determine the Correction Coefficient is through “Characterization”.<br />Albion Devices, Inc.<br />
  13. 13. Characterization<br />Empirical determination of Correction Coefficients.<br />Patiently heat and cool parts, masters and gages independently while taking measurements.<br />Results used to calculate linear coefficient.<br />Albion’s new software (DigiGage) includes a program that facilitates this procedure.<br />Albion Devices, Inc.<br />
  14. 14. Operator Involvement<br />Albion Devices, Inc.<br />Temp Comp systems are designed to run in the background.<br />Just need to be “Zeroed” when gage is zeroed (may sometimes be automatic).<br />System will automatically sense temperatures of work, master and gage, compute correction and apply it to measurements.<br />The result is that the gage displays dimension as if workpiece, master and gage were at nominal temperature (usually 68F/20 C)<br />
  15. 15. Temperature Sensors<br />Compromise between speed and durability.<br />Custom-designed for heavy duty, shop floor use.<br />They balance durability and speed of response.<br />Maintenance: Keep clean and free of chips, excess oil.<br />Graph above shows typical contact sensor asymptotic response curve.<br />Albion Devices, Inc.<br />
  16. 16. Success<br />Data obtained by Big Three auto co. Plug gage equipped with Albion’s temperature compensation system measuring aluminum housing bore.<br />Albion Devices, Inc.<br />
  17. 17. Digital temperature sensors and gaging probes<br />Albion Devices, Inc.<br />Fireball and DigiGage<br />
  18. 18. Fireball Temperature Sensors<br />Albion Devices, Inc.<br />Temperature sensors with direct USB connectivity.<br />DigiGage software programmable with all variables for temperature compensation algorithm.<br />DigiGage reads, calculates and displays.<br />
  19. 19. Fireball Digital Gaging Probe<br />Albion Devices, Inc.<br />Low cost per measurement channel. <br />Instant USB connectivity. <br />0.0001 mm/0.000005 inch accuracy and repeatability.<br />Various measurement ranges, linear throughout.<br />No expensive external signal conditioning and amplification circuitry.<br />Pre-calibrated at the factory.<br />Minimal setup time. Plug and play.<br />Requires single master only.<br />Multiple probes via USB ports on PC or hubs.<br />Optional interface to SPC programs.<br />
  20. 20. DigiGage Software<br />Albion Devices, Inc.<br />Multiple capabilities:<br />Temperature compensation offset output only.<br />Temperature compensated dimension output.<br />Gage probe display.<br />Can be configured to output offset to other gaging software. (Needs cooperation with software vendors or software engineers to create .dll).<br />DigiGage includes characterization routine.<br />
  21. 21. Complete Temp Comp System for PC<br />Albion Devices, Inc.<br />Combine:<br />Up to 8 temperature sensors<br />DigiGage software<br />A complete temperature compensation system based on a PC.<br />Runs in background, interfacing to customer’s preferred host SPC or gaging software.<br />
  22. 22. Albion Devices, Inc.<br /><br />Thank You<br />