Force Gage

Manufacturers like to count on PCE’s force gage items for precise and also quick and easy force testing. A force gage is used to test the quality, performance and – very importantly - the safety of a product as well as its compliance with industrial standards. A force gage is also used to assess mechanical as well as physical characteristics of a raw material or component during research and development as well as the design, manufacturing and assembly processes of a product. The possible applications of a force gage include the measurement of metals, packaging, paper, fabric and textiles, plastics, electronic and medical equipment, wires, electrodes, welds, springs as well as material composites.

The following text will help you find out what force gage is most suitable for your individual application.

Questions to Consider to Select the Right Force Gage

-  What type of force do you want to measure (e.g., compressive or tensile force, peel force, bending strength, torque, etc.)?    
- What kind of force testing system do you require for your measuring task (e.g., hand-held and portable force gage or a model with a non-portable force test stand or universal testing machine)?
- What minimum and maximum force do you expect (e.g., measurement range of 0 ... 5 kN)?
- What accuracy do you require to successfully complete your measuring task?
- What memory capacity and data interface is required, if any?
- How much after-sales support do you think you will require?
- How much is your budget?

The following text gives you a more detailed analysis of the criteria you have to bear in mind when looking for a force gage.

Types of Force
The force can be initiated in various ways. Tensile force can also be described as pulling force and compressive force, in other words, is the pushing force. When measuring the peel force or strength, the force is initiated by adhesion. Bending strength measurements are mainly performed on coatings to determine their elongation and/or deformability. Torque, on the other hand, is the force initiated by rotation. For torque meters, feel free to go to our torque meter / torque tester category.

Non-Portable or Portable
If you wish to use your force gage to sporadically make measurements for quality control, a portable force gage will be the right choice. If a more accurate and repeatable force measurement is required, it is recommended to use a stationary force test stand with your force gage. A force test stand does not only provide stability but it can also be equipped with a USB or RS-232 interface so that it can be controlled via a computer.

Measurement Range
For safety reasons, it is very important to choose a force gage that accommodates the maximum force you wish to measure. A buffer should also be taken into account if the required accuracy allows this. Also, possible risks must be eliminated before the force measurement. For instance, if there is a risk that the test material could get twisted during a tensile force measurement, the force gage must be secured with a clamp to prevent injury.

For measuring tasks requiring minimum force, spring scales can be used. These are easy to use and do not cost as much as many other force meters. Spring scales measure the weight and/or the force of an object that hangs down from its hook. The weight or force is normally measured in g, kg, lbs and / or N. A spring balance is a mechanical force tester that is ideal for force experiments in physics lessons as well as for showing the action and reaction in science, technology, engineering and math (STEM) classes and for lots of other educational applications. During a measurement, the spring is extended or pulled. When released, the spring returns to its original position.

A hydraulic force gage is another type of mechanical force measuring device and uses a hydraulic liquid to measure acting forces. The sensors of hydraulic force gages are designed for much wider measurement ranges than spring scales/balances. However, a hydraulic force gage will normally have a lower accuracy and resolution and little measurement traceability. This is why digital force gage models are more popular than analogue ones.

A digital force gage consists of a sensor and the evaluation unit. Most digital force gage models with lower measurement ranges are equipped with an internal sensor. Models with wider measurement ranges often come with a sensor that is connected to the gage externally. Most digital force gage devices measure both tensile and compressive forces and often some other parameters like the rotational speed or triaxle vibration. As not all parameters can be measured with a single sensor, most multi-purpose digital force gages are provided with adapters and some can do mathematical measurement conversions.

The maximum possible sampling rate is a very important factor when buying a digital force gage. The sampling rate is the frequency at which the transmitter checks the force sensor. It is normally indicated in Hz. For example, 500 Hz means that the force sensor is queried by the transmitter 500 times/s and the transmitter can change the measurement data 500 times/s. Lower-cost force gage models only have a sampling rate of 2 Hz. This sampling rate is fine for a slow force test but is not suitable for a tear test. Due to the long reaction time, a lot of measurement data would be lost during the tear test.

It must also be considered whether the transmitter is able to provide these many values in any acceptable form so that the measurement data can then be evaluated individually. Some low-cost transmitters can query the sensor, e. g. 1000 times per second but are not able to make the data available to the user in an appropriate way as the electronics are unable to process them at that speed. In that case, the average values are calculated.

The last type of force gage is rather high-priced but still very popular. It is called a highly flexible resistance strain gauge, commonly abbreviated as DMS which stands for the German word “Dehnungsmessstreifen”. A DMS is a thin film which a wire pattern or measurement grid is adhered to. This wire is powered by an external voltage and changes the conductivity or resistance in line with expansions and compressions. This change is repeatable and proportional so far that an external evaluation indicator can calculate the force. These DMS films are then attached (glued) to the measuring positions where the deformation can be recorded by means of the measuring grid. However, other influencing factors such as magnetic fields, temperature, humidity, etc., must be taken into account as these can affect the conductivity and thus manipulate the readings. Similar to force sensors, DMS films are placed where the force causes the most considerable deformation. However, the DMS strips must have a fixed connection to the ground and cannot be used again after they have been glued once.

Accuracy
The higher the maximum load of the sensor, the lower its accuracy will be. You will need to find the right compromise for your application. The accuracy specification of a force gage always depends on the range being measured. Logically, higher measuring precision will mean a higher price in most cases.

Price
When it comes to the budget, not only the cost of the force gage itself must be taken into account. Regular calibration costs, for example, should also be considered. For example, if you must meet the requirements of an ISO quality standard, a regular calibration interval must be met. ISO calibration costs occur at the time the force gage is purchased and reoccur annually or even more frequently, depending on your requirements regarding the accuracy and the usage of your force gage. Recalibration may also become necessary later due to the sensor drift that can occur over time. Costs for consumables such as (rechargeable) batteries and for spare parts should not be neglected either.

Memory Capacity
Data analysis is an essential factor for both short-term and long-term measurements. Data can be processed due to special functions of the transmitter / evaluation system and made available to the user. For instance, if the user only wants to measure the maximum force, the transmitter can show the highest value from the collected data (quantity of data depends on sampling rate) in the form of a PEAK or MAX value and filter out the other readings. If the user wants to have other readings such as the average value, another function or filter will be necessary. Ideally, all values collected after the force measurement can be saved. These raw data even allow the user to determine the desired results from the measurements already made later. The evaluation system or transmitter saves the measurement data to the internal memory and can make the data available to the user after the measurement. There is also a different way of saving the measured data: you can also transfer them to a storage device such as a data logger or computer by using a USB, RS-232, 4 … 20 mA or 0 … 10 V interface.

After Sales Support
It may also be a good idea to find out for how long the supplier has been operating. The longer the company has done business, the more likely it is that spare parts for your force gage will still be available to order a few years later. PCE Instruments was founded in 1999 and should be able to provide spare parts for all force gages that are still part of the company’s product range. You may also want to find out what kind of after-sales support will be available to you. You can call PCE Instruments to have a word with the technical advice team prior to purchasing to find out whether the level of service provided is sufficient for you.

More Information about Force Gage Devices
A force gage is used to measure the applied compression (push) or stretching (pull) or to define the torque. Depending on its type, a force gage allows the user to detect the force within ranges from hundredths of kN to MN.

There are mechanical and digital force gages.

A spring or lever is a resilient element in a mechanical force gage. The force affects the spring and either compresses or stretches it. A lever gauge is less accurate than a spring gauge. As a result of the force exertion, the lever is deformed. The disadvantages of mechanical force gages are their dependence on the temperature and the inaccurate reading by the human eye.

The electronic force gage is commonly used, in the production of automated technological systems, for the verification of mechanisms and in the automotive and transport industries. The main element in any electrical force gage is the strain gauge transducer. Different kinds of sensors can be used in electrical force gages, which widens the possibilities of application. These force testers give much more accurate results than analogue models as the data can be transferred to a computer via a cable and processed digitally. Electronic models convert the deformation of the resilient element into an electrical signal. A common example of use is the measurement of the compressive force of automatic doors which are often found in transport, gates and other areas.

In order to measure the muscle force of hands in medical environments, a handheld, portable force gage will be required. This type of force gage is frequently used in sanatoriums as well as other medical and sports institutions, etc. Meters to measure the muscle force of children often have a different housing size and shape. These force gages allow conclusions about the general physical condition of a patient and are absolutely necessary, for example, during rehabilitation to observe how the body develops after trauma.

Force gage devices specifically used in oil and gas production can provide the right information about emergency loads, test instruments and generate and print reports. The duration of a measurement is displayed at an accuracy of a second.

For laboratory experiments and for testing new equipment, electronic force gage models with microprocessor control are normally used. These force gages can be affixed to test stands.

A force gage can also be used for very special applications like, for example, when you want to find out the level of force necessary to break a shell of an egg. This will help you to find out the best ways of transporting the eggs.

A force gage can also be used in the chemical and textile industries, for example for checking how strong the fabric is or how fragile a material is. There are dozens of examples of possible force gage applications.

Pedal Force Gage
A pedal is a lever moved with the foot (per pedes = on foot). Pedals are frequently used to operate certain functions on vehicles, machines, devices, musical or other instruments with the feet. The force applied to the pedal by the foot can be transmitted either directly or after amplification or attenuation. Very different effects can be triggered by pedals. In motor vehicles, for instance, separate pedals are used for accelerating, braking and clutching. On machines, pedals can be used as safety or trigger switches. The force exerted by the operator's foot on the pedal to change its position is called the pedal force. The forces required to achieve the desired effect can be measured with the help of a pedal force gage. If the specified values are not achieved, the pedal must be replaced or readjusted.

If you have any further questions when choosing a force gage, please do not hesitate to contact us.