The Complete Guide to Force Measurement for Material Testing

Force measurement is one of the most fundamental methods of material testing and determines how a specimen will react under different loads or forces. It continues to be critical to the quality of end user products because it verifies material performance in applications where safety and reliability are essential, such as ensuring the strength of packaging seals or the precision of a syringe injection.  Even everyday products such as potato chip bags or cleaning wipes must withstand applied forces to maintain quality and usability.

Thwing-Albert Instrument Company is a leading manufacturer of testing machines and instrumentation in the United States. We specialize in reliable testing equipment and custom
solutions that help laboratories and quality control teams meet the highest quality standards. Here’s our guide to understanding force measurement in the context of material testing. 

Universal Testing Machine (UTM)

A Universal Testing Machine (UTM) typically measures force is designed to measure force and a wide range of material properties, including tensile, compression, peel, and tear strength. Often referred to as a tensile or pull tester, the UTM consists of an electromechanical system with a moving crosshead. The crosshead moves at a controlled speed — upward for tension and downward for compression. A load cell attached to the crosshead measures the applied force and converts the mechanical load into an electrical signal, allowing the system to record the material’s response with accuracy. 

How do you pick the right load cell? Consider the accuracy, resolution and load cell limits.

Load Cell Accuracy 

You can express load cell accuracy as a percentage of the full-scale output or reading. Verify load cells yearly to meet the published accuracy specification. 

Resolution

Resolution is the smallest detectable change in force measurement output and is determined by the A/D converter used, typically 16-bit or 24-bit. Resolution is important for accurate low-force detection when measured force values are small relative to the load cell capacity.

Repeatability

Repeatability is the system’s ability to produce consistent readings under identical conditions. Factors that may affect repeatability include system rigidity, load cell stability, and fixture
alignment.

Sampling Rate

How many readings per second the system captures is typically are expressed in Hz. Higher sample rates are recommended for short duration tests and tests that have significant force
fluctuations.

Load Cell Limits

A load cell, like any measurement, has specific limits and capacities that define its operational range and capabilities. Some of the limits include: 

1. Mechanical failure limit: This is the maximum force the load cell can endure without mechanical damage. 
2. Tare weight: This is the maximum weight you can zero out while allowing the load cell to use its full-scale capacity. 
3. Maximum capacity: This is the highest amount of force the load cell can measure accurately and safely. 
4. Overload capacity: The overload capacity is a built-in safety factor that allows you to load the load cell without damage. 

Types of Forces Measured

Force testing, otherwise known as force measurement, involves different types of forces — depending on the specific application, including:

• Tensile force
• Compression force
• Shear force
• Bending force

Transform Your Testing Capabilities

Equip your team with the tools they need to pioneer advancements and deliver excellence in every endeavor. Our machines support both standard tests and complex applications, providing the flexibility your quality lab requires. We offer a variety of load cells ranging from 5 N to 10 kN.

Request a quote today and see how a new or upgraded universal testing machine can enhance your lab’s performance.