Force measuring instruments are used to determine the amount of force applied during pushing, pulling, compression, tension and mechanical testing applications. They help laboratories, manufacturers, engineers and quality-control teams verify that products, components and materials perform safely and consistently.
Selecting the correct force measuring instrument is essential. A device with an unsuitable measurement range, poor accuracy or incorrect mounting arrangement may produce unreliable results, even when the instrument itself is functioning correctly.
This guide explains the main types of force measuring instruments, how they work, where they are used and the factors to consider when selecting equipment for a particular application.
What Is Force Measurement?
Force measurement is the process of quantifying a push or pull applied to an object. Force can cause an object to move, stop, accelerate, deform or break.
In physics, force is described using Newton’s second law:
Force = Mass × Acceleration
Force measurement is widely used to assess product strength, verify production processes, evaluate material performance and confirm compliance with quality or safety requirements.
Common force measurement tasks include:
- Measuring the force required to press a button
- Testing the strength of a cable or wire
- Measuring the force needed to open packaging
- Testing the compression resistance of a component
- Measuring the extraction force of a connector
- Evaluating the tensile strength of a material
- Testing springs, switches and mechanical assemblies
What Units Are Used to Measure Force?
The Newton, represented by the symbol N, is the standard SI unit of force.
Other commonly used units include:
- Kilonewton, kN
- Millinewton, mN
- Pound-force, lbf
- Kilogram-force, kgf
- Ounce-force, ozf
The appropriate unit depends on the force range, industry, testing standard and geographical market. Many digital force gauges allow users to switch between several measurement units.
For a more detailed explanation of force units and conversions, refer to the dedicated guide about the units used to measure force.
Main Types of Force Measuring Instruments
Different force measurement applications require different instruments. The most suitable option depends on the expected force range, required accuracy, test direction and whether the measurement must be performed manually or as part of an automated system.
Digital Force Gauges
Digital force gauges are portable electronic instruments designed to measure tension and compression forces. They normally use an internal load cell to convert the applied force into an electrical signal, which is then displayed as a numerical reading.
Digital force gauges may include functions such as:
- Peak force measurement
- Real-time force display
- Tension and compression modes
- Multiple selectable measurement units
- Data storage
- Pass and fail limits
- USB or computer connectivity
- Statistical analysis
- External sensor compatibility
These instruments are commonly used in laboratories, manufacturing facilities, quality-control departments and field-testing applications.
Mechanical Force Gauges
Mechanical force gauges use a spring-based mechanism and an analogue scale to indicate the applied force. They do not normally require a power supply and are suitable for straightforward measurements where advanced data collection is not required.
Mechanical gauges can be useful for basic inspections and field measurements. However, they generally provide fewer functions and lower reading resolution than digital models.
Load Cells
A load cell is a sensor that converts an applied force into a measurable electrical output. Load cells can be integrated into test systems, machinery, production lines and custom force measurement equipment.
Common load cell configurations include:
- Tension load cells
- Compression load cells
- Tension and compression load cells
- S-beam load cells
- Button load cells
- Pancake load cells
- Miniature load cells
Load cells are especially useful when the sensor must be installed separately from the display or connected to an automated control system.
Force Test Stands
A force test stand holds and moves a force gauge or load cell in a controlled and repeatable manner. Using a test stand can significantly improve measurement consistency compared with manually applying force.
Test stands are available with manual or motorised operation. Motorised systems allow users to control the test speed and movement more accurately, making them suitable for repetitive testing and formal quality-control procedures.
Universal Testing Machines
Universal testing machines are designed for more advanced tensile and compression testing. They are commonly used to evaluate the mechanical properties of materials, components and finished products.
Depending on their configuration, they can measure:
- Tensile strength
- Compression strength
- Elongation
- Breaking force
- Peel strength
- Flexural strength
- Shear strength
Universal testing machines are generally suitable for applications that require controlled movement, detailed test data and repeatable testing procedures.
Torque Measuring Instruments
Torque is a rotational force rather than a linear push or pull. Torque gauges and torque testers are therefore used when the application involves twisting, tightening or rotating a component.
Typical applications include testing bottle caps, fasteners, knobs, tools and rotating assemblies.
How Does a Digital Force Gauge Work?
A digital force gauge typically contains a strain-gauge load cell. When tension or compression is applied, the sensing element deforms slightly. This deformation changes the electrical resistance of the strain gauges attached to the sensor.
The instrument converts this change into an electrical signal and calculates the applied force. The result is then displayed on the screen in the selected measurement unit.
Digital force gauges can usually display both continuously changing force values and the maximum force recorded during a test.
Tension and Compression Force Measurement
Most force gauges can measure forces in two directions.
Tension Testing
Tension testing measures a pulling force. It is used when a component is stretched, separated or extracted.
Common tension tests include:
- Pull-off testing
- Wire and cable testing
- Connector extraction testing
- Seal strength testing
- Tensile testing
- Peel testing
Compression Testing
Compression testing measures a pushing or crushing force.
Common compression tests include:
- Button activation testing
- Spring compression testing
- Packaging compression testing
- Component insertion testing
- Tablet hardness testing
- Crushing resistance testing
The accessories and fixtures used during testing must be suitable for the required direction of force.
Applications of Force Measuring Instruments
Force measuring instruments are used across a wide range of industries because many products depend on controlled mechanical forces for safe and reliable operation.
Manufacturing and Quality Control
Manufacturers use force measurement to confirm that products meet design specifications and remain consistent between production batches.
Applications include:
- Testing assembled components
- Checking press-fit operations
- Measuring switch activation force
- Verifying connector insertion and extraction forces
- Testing welds, fasteners and seals
- Identifying production defects
Packaging Testing
Packaging must protect products while remaining practical for users to open and handle.
Force testing can be used to measure:
- Opening force
- Seal strength
- Peel force
- Closure force
- Compression resistance
- Tear strength
Medical and Pharmaceutical Testing
Force measuring instruments can be used when evaluating medical devices, pharmaceutical packaging and laboratory products.
Examples include:
- Syringe activation force
- Needle penetration force
- Tablet compression and hardness
- Medical device component testing
- Packaging opening force
- Closure and seal testing
Testing methods must follow the relevant procedures and regulatory requirements for the application.
Electronics and Electrical Components
Small electrical and electronic components often require highly precise force measurements.
Applications include:
- Keypad and button testing
- Connector insertion and withdrawal testing
- Cable pull testing
- Solder joint testing
- Switch activation testing
Automotive and Aerospace Testing
Force measurement is used to evaluate components that must withstand repeated loads, vibration and demanding operating conditions.
Applications may include:
- Spring testing
- Control and switch testing
- Component assembly verification
- Material testing
- Safety-system component evaluation
Research and Development
Researchers and engineers use force measurement equipment when developing new products, materials and testing methods.
Digital instruments with data-output capabilities are particularly useful because results can be recorded, compared and analysed over time.
How to Choose a Force Measuring Instrument
The correct instrument should match the expected forces, required accuracy and physical testing arrangement.
Determine the Required Force Range
The instrument must be capable of safely measuring the maximum expected force. However, selecting a capacity that is much higher than necessary may reduce the useful resolution of the measurement.
A suitable capacity should provide enough protection against overload while still allowing accurate measurement of the normal test force.
Consider Accuracy and Resolution
Accuracy indicates how closely the displayed measurement represents the actual force. Resolution refers to the smallest change in force that the instrument can display.
Applications involving small components or subtle force changes may require higher resolution than heavy industrial testing.
Identify the Direction of Force
Determine whether the application requires:
- Tension measurement
- Compression measurement
- Both tension and compression
- Rotational torque measurement
This decision affects the required sensor, fixtures and instrument configuration.
Select Suitable Fixtures and Accessories
The correct fixture helps apply force consistently and prevents the sample from slipping, bending or becoming misaligned.
Possible accessories include:
- Hooks
- Grips
- Compression plates
- Chucks
- Clamps
- Extension rods
- Test stands
Fixtures should match the sample shape, size and expected force.
Decide Between Handheld and Test-Stand Operation
A handheld force gauge may be sufficient for basic measurements and field inspections. However, manually applied force can vary between operators.
A test stand is generally recommended when the application requires:
- Repeatable test speed
- Consistent alignment
- Repetitive testing
- Higher forces
- Greater measurement accuracy
- Documented quality-control procedures
Review Data and Connectivity Requirements
Basic instruments may only display the current and peak force. More advanced devices can store data or transfer results to software.
Consider whether the application requires:
- Internal data storage
- Computer connection
- Real-time data transmission
- Statistical analysis
- Automated pass and fail limits
- Integration with other equipment
Why Alignment Matters During Force Testing
Correct alignment is essential for reliable force measurement. The applied force should normally travel directly through the measuring axis of the sensor.
Side loads, twisting and off-centre forces can cause inaccurate readings and may damage the instrument. A suitable test stand and correctly selected fixtures can help maintain proper alignment throughout the test.
Calibration and Verification
Force measuring instruments must be calibrated and checked regularly to maintain confidence in their results.
Calibration compares the instrument’s readings with known reference forces. The required calibration interval depends on factors such as:
- Frequency of use
- Working environment
- Accuracy requirements
- Testing procedures
- Quality-system requirements
- Risk associated with inaccurate results
An instrument should also be checked after an overload, impact, repair or any event that may affect its performance.
Common Force Measurement Errors
Several factors can reduce the reliability of force test results.
Selecting the Wrong Capacity
An instrument with insufficient capacity may become overloaded or damaged. An instrument with a capacity far above the expected force may not provide the required resolution.
Applying Force at an Angle
Misaligned force can create side loading and produce inaccurate readings.
Using Unsuitable Fixtures
Poorly selected grips or fixtures may allow the sample to slip, deform incorrectly or receive uneven force.
Testing at an Inconsistent Speed
Force values can vary depending on how quickly a sample is compressed, pulled or separated. Controlled test speeds improve repeatability.
Ignoring Calibration Requirements
An instrument that has not been calibrated or verified may provide readings that appear consistent but are inaccurate.
Overloading the Sensor
Applying force beyond the rated capacity can permanently damage the load cell. Operators should understand the instrument’s maximum capacity and overload protection limits.
Frequently Asked Questions
What instrument is used to measure force?
A force gauge is one of the most common instruments used to measure pushing and pulling forces. Load cells, force test stands and universal testing machines are also used depending on the application and required force range.
What is the difference between a force gauge and a load cell?
A force gauge is normally a complete instrument that includes a sensor, display and controls. A load cell is the sensing component that converts force into an electrical signal and usually requires a separate display, amplifier or control system.
Can a force gauge measure both push and pull forces?
Many digital force gauges can measure both compression and tension. The correct fixtures must be attached for the intended test direction.
Why should a force gauge be used with a test stand?
A test stand improves alignment, controls movement and reduces variation caused by manual operation. This can make test results more consistent and repeatable.
How often should a force measuring instrument be calibrated?
The correct calibration interval depends on use, environmental conditions, quality requirements and the importance of the measurement. Instruments used frequently or for critical testing may require more frequent calibration.
What happens if a force gauge is overloaded?
Overloading can damage the internal load cell and cause inaccurate readings. The instrument should be inspected and verified after any suspected overload.
Selecting Reliable Force Measuring Equipment
Reliable force measurement depends on more than selecting an instrument with the correct maximum capacity. The complete testing arrangement must also consider accuracy, resolution, alignment, test speed, accessories, data requirements and calibration.
A properly selected force gauge, load cell or testing system can improve quality control, reduce production errors and provide dependable information about product and material performance.
