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Types and Specifications of Strain Gages

Basic Structure

Strain gages are of the stucture, in which a metallic foil film in the thickness of a few microns is glued on a thin electrically insulated sheet (such as polyimide, polyester and so on). This foil film is cut down by photo-etching method in the shape of strain gages which can be made with the negative film masks of the strain gage patterns. These photo-etched strain gage patterns are trimmed to have a standard resistance value satisfying requirements as the strain gages. In addition, for strain gages in general applications, thermal resistance factors of the foil films are controlled to have three categories to match with the thermal elongation factors of 3 major and most popular materials of mild steel/11ppm, stainless steel/16ppm and aluminium alloy/23ppm, for which our strain gages can be self-temperature compensated to minimize temerature effects if specified so when ordering.

Standard Specifications

The following table gives a classification in accordance with the difference in materials of the strain gage grid holding base, namely, one is the polyester FA series and th other is the polyimide MA Series. The FA Series have abundant kinds of types and specifications and therefore are most suitasble for a wide range of strain measurements in general and on the other hand, the MA Series are suitable for strain measurements at medium and high temperatures and for the use as the elements in various industrial or scientific sensors.

>> Patterns and Specifications Table
Specification FA series MA series Unit and Note
Gage Length 0.3mm to 60mm 0.3mm to 60mm standard
Gage Resistance Within ±0.3% of the nominal resistance Within ±0.3% of the nominal resistance 120Ω to 1000Ω
Foil Material A : Cu-Ni Alloy A : Cu-Ni Alloy  
Base Material Polyester Polyimide  
Gage Factor 2.00 (Nominal) 2.00 (Nominal) 1.90 to 2.10
Measurable Strain 2 to 4% maximum 2 to 4% maximum Up to 10% with yielding strain
Temperature Range -30℃ to +80℃ -30 to +180℃  
Thermal Output ±2μst/℃(RT to +80℃) ±2μst/℃(RT to +160℃)
±5μst/℃(+160℃ to higher)
Compensated temperature range
Gage Factor Change with Temperature ±0.015%/℃ ±0.015%/℃ Refer to "Tech Information"
Fatigue Life More than 1×105 reversals More than 1×105 reversals at ±1000×106 strain
Applicable Linear Expansion Coefficient Common steel
Stainless steel
Aluminum alloy
Common steel
Stainless steel
Aluminum alloy
10.8ppm/℃
16.2ppm/℃
23.4ppm/℃

Configurations

Indication of types of strain gages produced by Showa Measuring Instruments Co., Ltd. is determined in the designation basing on the basic strain gage grid patterns to which some subordinate signs indicating the material of the strain gage grid holding substance, the foil material of the strain gage grid, the length of the strain gage grid, and so on.

Basic Patterns and Combinations
N 11 Uniaxial
N 22 Biaixal 0°/90°,stacked rosette
N 32 Triaxial 0°/45°/90°,stacked rosette
N 21 2-Element 0°/90°,plane layout
N 23 2-Element 0°,parallel layout
N 31 3-Element 0°/45°/90°,plane layout
N 34 Δ type 3-Element,plane layout
N 35 Y type 3-Element,plane layout
N 51 5-Element 0°,leads at one end
R 11 Uniaxial 90°,leads at one end
R 31 3-Element 90°,leads at one end
R 51 5-Element 90°,leads at one end
T 11 Uniaxial 0°,leads at both ends
T 24 2-Element 0°/90°,leads at both ends
U 11 Uniaxial 90°,leads at both ends
Z 11 Uniaxial 45°,for shearing strain
Z 23 2-Element ±45°,for shearing strain
Q 44 4-Element,for pressure sensor
Y 11 Uniaxial,for yield strain
C 11 For crack analysis
X 11 For crack propagation detection
P 11 For bolt spindle power measurement
Compensated Materials(ppm/℃)
11 Common steel(11.7)
  SUS630(10.6)
  SNCM(11.3)
16 Stainless steel / SUS304(16.2)
  Beryllium teel(16.7)
  Copper(16.7)
23 Aluminum / 2024-T4(23.2)
  Brass(21.0)
  Tin(23.0)
Optional Specifications / Leadwire
VS E Parallel vinyl-coated leadwire
  Length Select:1m,3m,5m
  size   Φ0.12*7(core)
  Resistance 0.44Ω/m(round)
VM E Parallel vinyl-coated leadwire
  Length Select:3m,5m
  size   Φ0.12*10(core)
  Resistance 0.32Ω/m(round)
VL E Parallel vinyl-coated leadwire
  Length Select:3m,5m
  size   Φ0.18*7(core)
  Resistance 0.20Ω/m(round)
FE --- Teflon-coated leadwire
  Length 3m
  size   Φ0.18*7(core)
  Resistance 0.20Ω/m(round)
L --- Polyester-coated leadwire
  Length Select:0.3m,0.5m
  size   Φ0.14*1(core)
  Resistance 2.24Ω/m(round)
W E Waterproof Moulded strain gage
  Length Select:1m,3m
  size   Φ0.12*7(core)
  Resistance 0.44Ω/m(round)
Color Code of VS type leadwire
Code E R W A B
Color Green Red White Gray Black
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