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Interface Differentiator is Proprietary Strain Gage Manufacturing

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Interface products have been heralded for their accuracy, reliability, and quality for more than 50 years. We credit our vertically integrated approach to manufacturing as the most significant factor in our development of industry-leading force measurement products, meaning we control every part of the design, manufacturing and testing of our products before they are shipped to our customers.

The process for how we differentiate ourselves begins with Interface strain gages. By manufacturing our own proprietary strain gages here at our headquarters in Scottsdale, Arizona, we can optimize our load cells to a quality level very few providers can match.

Think of strain gages as the heart and soul of a load cell. These components power every aspect of the device and their quality dictates a significant portion of the load cells’ overall quality. In addition, customization of the strain gages is a critical factor in ensuring the load cell is meeting the specific requirements of a customer’s project.

The last point is critically important because Interface does not just provide one size fits all products. Yes, we have a large standard product line ready to ship. There are many times when we collaborate directly with our customers to understand their application and the challenges that may be present during a force measurement testing program or OEM design. This allows us to offer modified and custom products that are engineered to order.  Whether that comes in the form of an off-the-shelf product within our catalog of more than tens of thousands of options, or a new model using our strain gage technology to meet the needs of a unique application.

An example of our commitment to meeting customer needs is the way we develop our strain gages to compensate for temperature, an environmental factor that can drastically affect the accuracy of force data. Our strain gages are designed and manufactured to counteract the temperature characteristics of the modulus of the load cell structural material.

The benefit to this is that our load cells are temperature-insensitive and do not require modulus compensation resistors, ultimately producing a simpler and more reliable circuit with higher output signal. It also means no dynamic thermal mismatch errors from modulus compensation resistors which cannot be thermally connected with the load cell’s surface at the strain gage location.

In addition, our proprietary strain gages provide several key benefits. Included below are a few of the differentiators available with Interface strain gages:

  • A higher output of 4mV/V, while competitors provide 3mV/V or less, which provides superior performance, flexibility, and accuracy.
  • The ability to perform hot and cold thermal compensation, from 15˚ – 115˚F, while competitors typically only provide heat compensation (60˚ – 160˚F).
  • Eight strain gages per load cell compared to our competitors four gages, which provides superior compensation of eccentric loads to further minimize resulting errors.
  • Our strain gages also offer:
    • Higher signal-to-noise ratio
    • Higher resolution in precision measurement applications
    • Superior fatigue life

Another factor in the development of our strain gages is our expertise and knowledge of the manufacturing process. We have always developed our own strain gages going all the way back to 1968. Therefore, we have learned everything there is to know about it and can guarantee the quality of our load cells in any environment based on this tenured expertise and having manufactured and calibrated millions of force measurement devices.

To learn more about our vertically integrated manufacturing process and the various forms of product and system customization we offer, contact our specialized application engineers.

 

Strain Gages 101

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A strain gage is a sensor that varies its resistance as it’s stretched or compressed. When tension or compression is applied, the strain gage converts force, pressure, and weight into a change that can then be measured in the electrical resistance.

At the heart and soul of every load cell is a strain gage. This is the pinnacle technology that allows engineers to collect and analyze force data. In the industry, it is known as force measurement.

Strain gages are made through a photo-etch process using a flexible backing and a very thin foil. The way a strain gage works is when the backing and foil stretches or compresses, resistance goes up and down respectively. We know this as force. Think of stretching like a three-lane highway switching to two lanes, and vice versa for compression with two lanes going into three. As the load cell’s internal strain gage experiences force, it sends a signal with a precise measurement of the amount of force it’s experiencing.

There are many different types of strain gages for a variety of environments and force measurement needs. The major difference in strain gages is the base material used in the manufacturing process. Different materials are used when a load cell needs to perform optimally in a variety of temperatures, humidity levels, and elevations. Matching the correct strain gage and a load cell to the customer’s needs is critical to accuracy.

“Here at Interface, we pride ourselves on developing the most accurate force measurement tools, and it starts with our proprietary manufacturing of the strain gage.”  Scott Dunne, Production Engineering Manager

More than 52 years ago, when our founder Richard F. Caris started Interface, he purchased over a mile of foil, which is the base material used in strain gages. Caris understood the only way to ensure Interface customers received quality results from their force measurement products was to control every aspect of engineering design, product development, and production.

The key ingredient to our precision accuracy and reliability is the fact that we have vertically integrated the entire manufacturing process from design to production and have a deep understanding of the materials necessary to suit every client’s need for optimal results

Many load cell makers purchase their strain gages from a third party. This means there’s more variability in their manufacturing process and you often find the variances in their materials clash and diminish the accuracy, or they are not correctly suited for the customer’s project requirements.  Interface makes all their own strain gages.

We have learned everything there is to know about strain gage manufacturing and can guarantee the quality of our load cells in any environment based on this tenured expertise and having manufactured and calibrated hundreds of thousands (ok, millions) of force measurement devices. And here’s a fun fact, although we’ve manufactured hundreds of thousands of load cells and strain gages, we haven’t even used half of the original mile of foil we purchased in 1968. Good product managed well can go a long way!

For more information on Interface’s commitment to accuracy and reliability, we have written The Load Cell Field Guide, the definitive resource on load cells. It is available on Amazon. You can also download our latest technical white paper, Contributing Factors to Load Cell Accuracy, for free by clicking here.

Contributor:  Scott Dunne, Production Engineering Manager, Interface