Temperature CompensationTemperature Compensationand railroad wheelset precision and railroad wheelset precision dimensional measurementsdimensional measurements

by Albion Devices, Incby Albion Devices, Inc

This is a MS Powerpoint presentation. Please use mouse clicks, space bar or arrow keys to move between slides.

Albion - the leader in temp comp• Railroad wheelsets include

some components that have tight tolerances. For example, the AAR requires that axle journals and bearing races (cones) are finished to dimensions measured in tenths of thousands of an inch.

• It can be hard to hold these tolerances consistently in changing temperatures.

This is a MS Powerpoint presentation. Please use mouse clicks, space bar or arrow keys to move between slides.

Albion - the leader in temp comp

• Most railcar axle journals and bearings are approximately 5 to 7 inches in diameter.

• Over a temperature range of 40ºF to 140ºF (4ºC to 60ºC)

their diameters will change by .0050 to .0070 inch (0.13mm to 0.18mm).

This is a MS Powerpoint presentation. Please use mouse clicks, space bar or arrow keys to move between slides.

Albion - the leader in temp comp• Maximum tolerance is usually no more than

+/- .0005 inch (+/- 0.013mm).• Albion’s gages repeatably correct all measurements

to the International Reference Temperature of 68ºF (20ºC) to within +/- .0002 inch (+/- 0.005mm) over a temperature range of 40ºF to 140ºF (4ºC to 60ºC)

This is a MS Powerpoint presentation. Please use mouse clicks, space bar or arrow keys to move between slides.

Albion - the leader in temp comp

• All metals expand and contract as temperatures vary. By eliminating these effects from precision measurements, our gages provide repeatable and reproducible measurements year round in all climates and working conditions.

This is a MS Powerpoint presentation. Please use mouse clicks, space bar or arrow keys to move between slides.

• Albion Devices, Inc., is the world leader in temperature compensation of precision dimensional measurements.

An Introduction to TComp

This is a MS Powerpoint presentation. Please use mouse clicks, space bar or arrow keys to move between slides.

• Albion Devices, Inc., developed TComp (“tee-comp”) temperature compensated snap gages and bearing cone gages specifically for the railroad industry and in consultation with key AAR officals. The unique, built-in temperature compensation capabilities of these units make them the most consistently accurate shop floor snap gages and bearing gages available.

TComp digital indicator.

• The TComp digital indicator lies at the heart of our railroad gages. It is a small, battery or mains powered, micoprocessor-based system that is designed to fit on a custom snap gage frame or other gage fixture so as to take temperature compensated comparative measurements.

• Mounted on a manually operated snap gage, TComp can produce accurate and repeatable measurements to within + / - .0002 inch (5 microns) or better, over a temperature range of 40ºF to 140ºF (5ºC to 60ºC).

Snap Gage configuration

Stack gage

• Dual TComps can be mounted into a specially designed bearing cup gage, called a “stack gage”, used extensively in the railroad industry.

Fixture mounted applications• Mounted in a fixture or a

stand, TComp is capable of accurate and repeatable measurements to within + / - .0001 inch (2.5 microns) or better, over a temperature range of 40ºF to 140ºF (5ºC to 60ºC) on the shop floor.

• Tcomp can also be mounted on a bar gage for critical large diameters.

Tcomp’s transducers• TComp indicator is equipped

with a transducer assembly that contains 3 sensors: an LVDT, a workpiece/master temperature sensor (that senses through the carbide face of the measuring anvil) and a gage fixture temperature sensor (that monitors the temperature of the frame or fixture in which it is mounted).

Workpiece sensor

LVDT

Gage sensor

Controls

• TComp is programmed and operated through a simple touch pad on the front panel.

• An LCD displays data and measurements.

Transducers

• LVDT probe and temperature sensors are mounted within the gage fixture so as to make suitable contact with respective components.

• The “Gage” sensor monitors the temperature of the snap gage frame. The “Workpiece” sensor senses the temperature of the workpiece and the master.

Operation• In operation, TComp notes the

temperature of the master during the mastering (zeroing) cycle, then switches automatically into Measure Mode. In this mode it assumes that it is measuring a workpiece and applies the respective correction coefficient. Meanwhile, the gage sensor applies yet another coefficient to any changes in gage fixture or frame temperature.

Compensation Algorithm• TComp’s programmed

algorithm takes into account any variation in the temperatures of the workpiece, master or gage fixture (the “elements” of the measurement system) from Nominal Temperature (usually 68°F/20°C).

WorkpieceTemperature

MasterTemperature

GageTemperature

WorkpieceCoefficient

MasterCoefficient

GageCoefficient

CompensationAlgorithm

TemperatureCorrectedDimension

Algorithm (cont)• TComp applies these variations to user-programmable

correction coefficients (expansion coefficients) and to the user programmable nominal dimension (since coefficients are expressed in terms of size variation (inch or MM) per degree of temperature (°F or °C) per unit of dimension (inch or MM)).

Correction to 68°F/20°C

• The net size variation after allowing for expansion or contraction in all 3 elements is applied in real time to dimensional measurements made by TComp’s LVDT.

• The result is that all displayed dimensions show the size that the workpiece would measure if it, the master and the gage frame were all at Nominal Temperature (68°F/20°C).

Temperature sensing

• The key to the success of TComp’s system is in accurate and rapid temperature sensing.

• This is accomplished by using stable and accurate electronic chip and thermistor technology housed in protective housings within the gage.

The Dramatic Potential

Temperature Compensation of precision gaging provides dramatic improvement in:

• Process control• Gage repeatability• Gage correlation• Scrap and rework reduction• Overall quality control

Product Range

• The remarkable thermal correction capabilities of TComp can be applied to a wide range of gages. Be sure to ask us about our other temperature compensated gages and systems.

Thank you for viewing this introduction to TComp. We hope that you found it useful and informative.

Albion Devices, Inc.742 Genevieve Street, Suite L

Solana Beach, CA 92075858-792-9585

adi@AlbionDevices.comwww.AlbionDevices.com