Try this self-administered test of your knowledge of Temperature
Compensation (just 12 questions). It's OK, no-one gets to know
how you score unless you
tell them!
Over the typical maximum range of temperatures experienced on
the shop floor (say, 50° F to 140° F, or 10° C to 60° C)
Coefficients of Expansion (COE) for the most commonly machined
metals are practically linear. However, COEs are typically
expressed in handbooks only to within +/- 10% or so, because of
uncertainties. Can you associate the following approximate COEs
(expressed in parts per million per ° F or "ppm/°F")
with their respective metals?
1) The approximate COE of Steel is:
- 12.2 ppm/°F
- 6.5 ppm/°F
- 10.0 ppm/°F
- 5.5 ppm/°F
2) The approximate COE of Aluminum is:
- 12.2 ppm/°F
- 6.5 ppm/°F
- 10.0 ppm/°F
- 5.5 ppm/°F
3) The approximate COE of powdered metals is:
- 12.2 ppm/°F
- 6.5 ppm/°F
- 10.0 ppm/°F
- 5.5 ppm/°F
4) What is the standard international reference temperature at
which all measurements are specified, as stipulated by ISO and
ANSI? (Hint: See our Home page)
- 32° F (0°
C)
- 50° F (10°
C)
- 68° F (20°
C)
- 86° F (30°
C)
5) What is the difference between an "accurate" and a
"precise" gaging system? (If you don’t know the
answer to this one you may be experiencing gaging errors without
knowing it. You might find the article "On Target with Minimum Variance",
published by Quality in Manufacturing magazine, useful).
- a precise gage has greater resolution than an accurate
gage
- a precise gage has better R & R than an accurate
gage
- there is no difference
- an accurate gage gives results which are closest to
true dimension, while a precise gage is repeatable, even
if inaccurate.
6) Which "elements" of a measurement system (gage)
can contribute to temperature induced error? A good example of
such a system can be found here.
a. workpiece
b. gage fixture
c. setting master
d. all of the above
7) How large a dimensional variation will be observed in a three
(3) inch (76 mm) aluminum component as a result of it changing
temperature by 20° F / 11°
C, say from 65° F / 18°
C to 85° F / 29°
C? - Calculators allowed. (Clue: coefficient of expansion for
aluminum is the answer to question 3.) A good example of such a
part is an auto engine piston. See our Application
Note on temperature compensating piston gages.
- .0004 in / 0.010 mm
- .0006 in / 0.015 mm
- .0008 in / 0.020 mm
- .0010 in / 0.025 mm
8) How large a dimensional variation will be observed in a three
(3) inch (76 mm) steel component as a result of it changing
temperature by 20° F / 11°
C, from 65° F / 18°
C to 85° F / 29°
C? - Calculators allowed. . (Clue: coefficient of expansion for
steel is the answer to question 2.)
- .0002 in / 0.005 mm
- .0003 in / 0.0075 mm
- .0004 in / 0.010 mm
- .0006 in / 0.015 mm
9) What do the letters "TEI" stand for? (Hint:
visit our Library and look through the Papers).
a. Theorized Expansion Indicator - an estimate of
thermal expansion coefficient
b. Thermal Error Index - an ANSI defined estimate of
overall thermal error in a measurement system
c. Temperature Equalization Inversion - the amount of
thermal error offset experienced when setting master and
gage vary in temperature by the same amount
d. Thermal Energy Input - the amount of thermal energy
generated in a part as a result of a production process
10) What is a Full Electronic Temperature Compensation
System? Albion's GageComp system is
just one of our systems in this category.
a. a system of temperature sensors and an
electronic controller which senses temperatures of master,
workpiece and gage fixture during measuring operations and
generates a real-time net correction for thermal errors
b. a sensor and electronic interface which senses the
temperature of parts while they are being measured
c. a method by which temperature is controlled at
nominal temperature
d. an off line computer into which an operator punches
temperatures and dimensions in order to calculate thermal
errors
11) Approximately how much of the thermal error in a
measurement should an Electronic Temperature Compensation System
consistently eliminate?
a. 80% or better
b. 92% or better
c. 65% or better
d. 50% or better
12) What is the principal benefit of a Temperature
Compensation System?
a. measurements are always given at reference
temperature, regardless of actual temperatures
b. the system constantly displays the temperatures of
workpiece and gage during measuring operations
c. a cheaper coolant can be used in metal cutting
processes
d. machine operators can take the afternoon off
Scoring: If you scored
more than ten correct, you must have done some excellent
research, or maybe you have a temperature compensation system
already installed. Eight to ten right is impressive - you
already have a good start on the subject. Less than eight
correct - maybe you need to find out more about this technology
of the present and future.
Answers: 1-b, 2-a, 3-c, 4-c, 5-d, 6-d, 7-c, 8-c, 9-b, 10-a,
11-b, 12-a
