Gage Series
Advanced Sensors
N2A SERIES
N2A gages are oconstantan-alloy patterns constructed on a thin, laminated, polyimide-film backing. This
series is capable of low and repeatable creep performance. Construction is very rugged, which will help
prevent gage handling damage. Advanced Sensors N2A gages are offered with epoxy encapsulation as
standard. An open-faced version can be supplied upon request.
J2A SERIES
J2A gages are encapsulated constantan-alloy patterns. Both the encapsulation and backing are thin,
laminated polyimide film. Gage soldering tabs are exposed for simplified lead connections. Creep
performance is equal to the N2A Series, although the presence of an encapsulating layer will require a
change in creep code selection to maintain the same performance.
N2K SERIES
N2K gages are modified-Karma-alloy patterns constructed on a thin, laminated, polyimide-film backing. All
N2K gages are supplied with gold soldering pads (DG) for ease of leadwire attachment. Copper soldering
pads are also available. Most gages in the N2K Series can also be modulus compensated. Advanced
Sensors N2K gages are offered with epoxy encapsulation as standard. An open-faced version can be
supplied upon request.
N5K SERIES
N5K gages are modified-Karma-alloy patterns constructed on a thin, laminated, polyimide-film backing constructed to improve
gage performance at elevated temperatures. All N5K gages are supplied with gold soldering pads (DG) for ease of leadwire
attachment. Copper soldering pads are also available. Most gages in the N5K Series can also be modulus compensated.
Advanced Sensors N5K gages are offered with epoxy encapsulation as standard.
J5K SERIES
J5K gages are encapsulated, modified-Karma-alloy patterns specially constructed to improve gage
performance at elevated temperatures. Because of the laminated polyimide-film backing and encapsulation,
all J5K patterns are fully flexible without being brittle. Gold soldering pads (DG) as well as copper soldering
pads (DP) are exposed for simplified lead connections. Some J5K gages can be supplied with modulus-
compensation (EMC) options. For best high-temperature performance, J5K-Series gages should be installed
with M-Bond 450 high-temperature adhesive.
GAGE
SERIES
N2A
J2A
N2K
N5K
J5K
TEMPERATURE RANGE
STATIC
–100° to +200°F
(–75° to +95°C)
–100° to +200°F
(–75° to +95°C)
–100° to +200°F
(–75° to +95°C)
–100° to +400°F
(–75° to +205°C)
–100° to +400°F
(–75° to +205°C)
DYNAMIC
Same as Static
Same as Static
Same as Static
–320° to +500°F
(–195° to +260°C)
–320° to +500°F
(–195° to +260°C)
GAGE FACTOR
(SEE NOTE)
2.05 nom.
2.05 nom.
2.1 nom.
(1)
2.1 nom.
(1)
2.1 nom.
(1)
FATIGUE LIFE
STRAIN LEVEL IN µ
ε
±1500
1500
±1700
1700
±1800
±1800
± 2000
1800
NUMBER OF CYCLES
10
7
10
8 (2)
10
6
10
7 (2)
10
7
10
7
10
7
10
8 (2)
Notes:
Advanced Sensors gages are supplied with nominal gage factor values that will vary slightly with pattern. They are not suitable for
strain measurement in stress analysis applications. Request our Precision Strain Gages databook, or contact our Applications
Engineering Department, for a complete listing of gages for precision strain measurement applications.
(1)
Nominal gage factor is 2.2 for EMC options.
(2)
Unidirectional strain.
Document No.: 11379
Revision: 18-Nov-2015
For technical questions, contact
mm@vpgsensors.com
www.micro-measurements.com
5
Creep and Modulus Compensation
Advanced Sensors
CREEP COMPENSATION
Commercial transducers regularly achieve a creep
specification of less than ± 0.02% of full scale (FS) for a
20-minute test. To attain this level on a high production
basis, it is usually necessary to match the strain gage’s
creep characteristic to the spring element creep.
Most
Transducer-Class
gages can be adjusted in design
to exhibit either a positive or negative creep under load.
Spring element materials exhibit only positive creep under
load. (See figure below.)
Positive Creep
Zero Creep
Transducer
Output
Negative Creep
Properly matched to the transducer spring element,
these EMC (Effective Modulus Compensation) gages
can provide very good self-correction of changes in
transducer span versus temperature. A compensation
better than ±0.0008%/°F (±0.0014%/°C) can readily be
achieved in many cases.
While this may at first appear to be the “ideal” strain
gage for transducers, there are certain factors that should
be considered prior to selecting EMC gages for a given
application:
1.
EMC gages cost more than other gages. In most
cases the difference is great enough to offset the
additional cost of span/temperature resistors.
EMC gages must be “matched” to the transducer
spring material. Depending on the degree of
compensation accuracy desired, the standard EMC
options may not yield the “best fit” compensation on
the spring material in use. In these cases, a special
foil lot which possesses the desired compensation
would be required. There is normally a minimum
order requirement and set-up charge for special
foil lots.
Transducer spring materials may not have
batch-to-batch repeatability sufficient to maintain
specifications when using the same EMC gages. New
material lot testing is therefore necessary for high
precision units.
2.
Load
Applied
Time
Since transducer creep depends on several variables
such as spring element material, heat treatment, strain
field, adhesive type and test temperature, it is not
possible to predict the proper gage compensation
necessary to achieve the best creep result.
Most of the gages in this catalog list one available
creep compensation code. Since it is not possible to
predetermine the creep characteristics of a particular
transducer, it is suggested that the standard creep code
be ordered in quantities sufficient to evaluate three or
four transducers. Where creep levels are high enough to
warrant correction, a different creep compensation, either
more negative or more positive, depending on test results,
can often be recommended.
A complicating factor in creep code selection is that while
different gage patterns may list the same creep code, they
do not necessarily exhibit the same creep behavior. This
is because the gage backing selection, gridline width and
gage length also influence creep characteristics.
It should also be noted that this type of creep correction
is generally limited to transducers exhibiting less than
±0.1% FS creep. Higher creep levels in the positive
direction are often the result of poor spring element
material selection. Negative creep values in excess
of 0.1% FS generally are the result of a faulty gage
installation.
3.
Despite these limitations, EMC gages can often be
advantageous for transducer manufacturers.
The following standard EMC options are available:
OPTION M1
Gage factor slope is –1.50% per 100°F (–2.70% per
100°C). Provides span-versus-temperature compensation
for many stainless steels.
OPTION M2
Gage factor slope is –2.35% per 100°F (–4.23% per
100°C). Provides span-versus-temperature compensation
for most aluminum alloys.
OPTION M3
Gage factor slope is –1.25% per 100°F (–2.25% per
100°C). Provides span-versus-temperature compensation
for many tool steels.
OPTION M4
Gage factor slope is –1.35% per 100°F (–2.43% per
100°C). Provides “mid-range” compensation between M1
and M3.
MODULUS COMPENSATION (EMC) OPTION
Many of the K-alloy gages in this catalog are available in
a special form which permits the gage factor change with
temperature to be adjusted over a wide range during gage
manufacture.
www.micro-measurements.com
6
For technical questions, contact
mm@vpgsensors.com
Document No.: 11380
Revision: 21-Sep-2015
Designation System
Advanced Sensors
Self-Temperature-Compensation (S-T-C)
Foil Alloy
Carrier Matrix (Backing)
Pattern Code
Resistance in Ohms
Gold/Copper Soldering Pad
Optional Grid
Encapsulation
Feature
Example: XXX - XX - S5XXXX - XXX / DX / EX
N2:
Special polyimide
J2:
Encapsulated N2
N5:
High temperature N2
J5:
High temperature J2
A:
Constantan
K:
Modified Karma
6-digit code, with the first
characters “S5”, and the last
character a creep code letter,
where applicable.
Resistance
in Ohms,
(C = x 100)
Self-Temperature-Compensation (S-T-C) number
approximating the thermal expansion coefficient of
the transducer material in ppm/°F. S-T-C values of
06 (steels) and 13 (aluminum alloys) are normally
stocked. MC is substituted for S-T-C for modulus
compensated gages.
DG:
Standard Gold plating on N2K, N5K, J5K series.
DP:
Copper plating option available upon request.
E3:
0.0004-inch (0.01 mm)-thick epoxy film covering
of sensing grid. Solder tabs exposed.
E4:
A softer version of E3 for better gage flexibility,
with same film thickness.
E5:
0.0004-inch (0.01 mm)-thick film covering of
sensing grid with extremely high elongation.
Solder tabs exposed.
Document No.: 11381
Revision: 04-Jan-2016
For technical questions, contact
mm@vpgsensors.com
www.micro-measurements.com
7
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