Strain gauge A strain gauge (or strain sensor) is a type of electronic component used to measure the deformation (stretch) of an object when a force is applied. Essentially, when an object is stretched or compressed, the strain gauge attached to its surface will also deform. This change in shape alters the sensor's resistance. By measuring this change in resistance, we can accurately calculate the degree of stress and strain in the material.

Based on their structure and intended use, strain gauge They are divided into the following main categories:

Classification by structure:

• Foil Strain Gauge (Metal foil type): This is the most common type currently available (like the models from...). KYOWA good SSHOWAIt consists of an extremely thin metal mesh bonded to an insulating film. Its advantages are that it is inexpensive, stable, and easy to use in industry.

KYOWA Strain gages KFGS-2-120-C1-27 L5M3Y stress sensor (3-wire/120Ω)

• Wire Strain Gauge (Metal Wire Type): Use thin wires instead of metal foil. While less common than foil, it is still used in some high-temperature measurement applications.
• Semiconductor Strain Gauge: Made from semiconductor material (usually silicon). This type has extremely high sensitivity (Gauge Factor), dozens of times higher than foil, but is very sensitive to temperature and easily broken.

Classification by shape and measurement direction

• Single-element sensor: There is only one grid direction, used to measure strain along a defined axis.
• Rosette Strain Gauge: It consists of multiple resistive sheets (usually 2 or 3) stacked or placed side-by-side at 45° or 120° angles. This type is used to determine the direction and magnitude of strain in complex planes when the direction of the force is unknown.
• Shear Gauge: Specifically designed to measure shear stress or torque on rotating shafts.

How to attach a strain gauge to a product.

Classification by specific purpose

• High-temperature gauge: Uses special adhesives and materials designed to operate in high-temperature environments (up to 300°C ~ 800°C).
• Waterproof Gauge: Pre-coated with a waterproof protective layer, suitable for underwater installations or wet environments.
• Post-yield Gauge: Used to measure extremely large deformations (exceeding the elastic limit of the material), commonly used in fracture strength testing.

To use a strain gauge to measure the full strain of a product, you need more than just individual strain gauges; you need a complete measurement system.

1. Strain Gage (Direct Sensor)

Depending on the product material, you choose the appropriate model. Kyowa or Showa.

• For metal/steel (most common): Model KFGS-5-120-C1-11 (Kyowa) or line N11 (Showa)This is a versatile, highly stable foil gage.
• For plastics/composites: Model KFRPB (Kyowa) – designed for materials with low stiffness.
• If you don't know the direction of the force: Which one should I choose? Rosette Gage (a type with 3 stacked resistor sheets, for example: KFGS-5-120-D17-11) to measure deformation in all directions.

2. Adhesive (Specialized glue)

Adhesives are a crucial component for transmitting deformation from the product surface to the sensor.

• Fast-drying glue (Cyanoacrylate): Model CC-33A or CC-36 (Kyowa). This type dries in 30-60 seconds and is used for quick measurements at room temperature.
• Heat-resistant/long-lasting adhesive: Model EP-340 (Epoxy type) if you need to take measurements for extended periods or in harsh environments.

3. Wires and Connection Accessories

• Lead wire: The 3-wire system provides temperature compensation, resulting in more accurate results.
• Terminal: Example line T-Type (Kyowa), used to connect the wire from the gage to a long cable, preventing the gage pins from breaking when stretched or extended.

4. Data acquisition device (Data Logger / Amplifier)

This is the "brain" that converts electrical signals into numbers displayed on the screen.

• Handheld (simple) version: Model PCD-400A or PCD-430A (Kyowa). Compact, connects directly to the computer via USB.
• Static mode (slow measurement, multiple channels): Current UCAM-60B or UCAM-550Suitable for measuring the structure of factory buildings and bridge beams.
• Dynamic mode (vibration and impact measurement): Current EDX-100A or EDX-200AUsed for testing cars and airplanes.

5. Data processing software

• Often bundled with the manufacturer's data collection equipment (such as software). DCS-100A (from Kyowa). It helps you plot graphs, calculate stress, and export reports to Excel.

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SEMIKI is the authorized distributor of Strain Gage. Kyowa Electronic Instruments and Showa Measuring Instruments (Micro Showa) In Vietnam, various measurement solutions are available to suit different testing needs, such as measuring vehicle glass deformation, PCB deformation, bridge and road deformation, etc.

Kyowa Electronic Instruments is the first manufacturer of strain gauges in Japan, with over 50 years of experience. Their products are renowned for their extremely high accuracy and diverse measurement capabilities. 

• Typical applications:
  • Structural strength analysis: Used to measure stress in social infrastructure, aircraft, automobiles, and ships to ensure safety.
  • Measurement in harsh environments: The KFU series can withstand high temperatures up to 350°C. $$Suitable for engine parts or machinery that operate continuously.
  • Checking the printed circuit board (PCB): The KFRS series is specifically designed for evaluating the mechanical and thermal characteristics of printed circuit boards in electronic devices.
  • Sensor components: It serves as the core for load cells, pressure sensors, acceleration sensors, and torque sensors.

* Showa Measuring Instruments We started producing strain gauges in 1962 and have focused strongly on foil gauges with high durability and stability. 

Industrial measuring equipment: Showa products are often integrated into in-factory quality control systems due to their ability to measure dimensional changes at extremely small levels. 1/1,000,000 of a unit length)

Typical applications:

Measuring diverse materials: Suitable for stress analysis on a wide variety of materials such as metals, rubber, plastics, and ceramics.

Monitoring of civil engineering structures: Product lines such as N11-FA are commonly used in experiments measuring stress and strain in construction materials.

Comparison table between Kyowa and Micro Showa

Characteristic	Kyowa	Showa (Micro Showa)
Strengths	Diverse product range, cutting-edge technology.	High durability of metal foil, good thermal stability.
Main areas	Aviation, automobiles, high-tech electronics	Heavy industry, building materials, rubber
Measurement capability	From static to dynamic (above) )	High sensitivity to low-elasticity materials

To select the most suitable strain gauge, ensuring accurate data and preventing data loss during measurement, you need to consider the following five core criteria:

1. Material of the product to be measured (Coefficient of thermal expansion)

This is the most important factor. Each material (steel, aluminum, plastic) has a different thermal expansion coefficient. You should choose a strain gauge that... Self-temperature compensation corresponding:

• Code -11: For use with steel/iron.
• Code -16: For use with copper/copper alloys.
• Code -23: For use with aluminum.
• For example: Model Kyowa KFGS-5-120-C1-11 with a tail -11 That means it's specifically for steel.

2. Gauge Length

• Homogeneous materials (Metals, Plastics): Use the type with a short mesh length.1mm, 2mm, or 5mm) to accurately measure at points of low stress concentration.
• Heterogeneous materials (Concrete, Wood): You must use the type with long mesh.20mm to 100mm) to obtain the average value of the entire area, avoiding errors caused by encountering pebbles or wood grain.

3. Gage Pattern

Depending on whether you already know the direction of the force or not:

• Uniaxial form: There is only one grid direction. Use this when the direction of deformation is known with certainty (for example, straightening a steel bar).
• Rosette style (2 or 3 directions): Use when The direction of the force is unknown.The 3-directional type (0°, 45°, 90°) allows you to calculate both the magnitude and direction of the principal strain.
• Torque measurement type (Shear/Torque): There are V-shaped grids, specifically designed to be attached to rotating shafts to measure torque.

4. Working environment temperature

• Room temperature (Below 80°C)C): Use common types (Kyowa's KFGS series or Showa's N11 series).
• High temperature (100°C ~ 300°C): You must use a specialized product (such as Kyowa's KFU Series) with heat-resistant epoxy adhesive.

5. Resistance of the Strain Gage

• 120 Ohm: This is the most common type, compatible with most amplifiers (Data Loggers).
• 350 Ohm: Use this when you need to reduce heat dissipation on the gauge or when the cable connecting the gauge to the measuring device is too long (to reduce interference).

You can contact SEMIKI Company for expert advice and to purchase strain gage equipment. In the Vietnamese market, SEMIKI We are a reputable company with many years of experience in distributing and supplying measurement solutions from Japanese manufacturers such as Kyowa and Micro Showa.

Why you should contact SEMIKI for Strain Gage:

In-depth technical consultation: Their technical team can help you choose the right model based on the material (steel, aluminum, plastic), ambient temperature, and measurement purpose (static or dynamic).

Providing complete solutions: In addition to the strain gauge, they offer a full range of accessories, including:

• Specialized adhesive: CC-33A, CC-36, EP-340.
• Meter/Amplifier: Kyowa's PCD, UCAM, and EDX series.
• Surface preparation equipment: Sandpaper, chemical cleaning solution.

After-sales support: Instructions on how to properly apply the Gage seal (incorrect application can lead to significant inaccuracies or sensor damage).

Contact Semiki:

Website: You can find out more details and send a consultation request via Semiki.com.

Business email: [email protected]

Phone number (Hotline): +84 979 761 016.