We understand that choosing the right sensor is a daunting task, as there is no real industry standard on how you go about selecting one. There are also some challenges you may encounter, including finding the compatible instrumentation or requiring a custom product that would increase the product’s delivery time. We've outlined some steps to help you get started on choosing the perfect load cell for your application.
Step 1 - Understand what you are measuring
After you've determined your application, define what you want to measure. Do you want to measure load? This means that you want to convert input mechanical force into an electrical signal. Note that load cells are different from pressure sensors. Load cells can be used to measure surface pressure. You would use a pressure sensor if you need to measure fluid or gas pressure. Load cell applications include pressure-to-viscosity/liquid separation, automation, medical bag weighing, and many more. Here are a few examples of load cell applications that may help guide you in your selection.
Step 2 - Define key characteristics
Next, you should take a look at some of the characteristics that would define your needs. Do you have a static load or a dynamic load? Define the mounting type. How will you be mounting this load cell? Is it female/male thread, in-line, side mount, flange mount, thru-hole, or compression washer? What is your load direction? (Tension, compression, or both?)
Step 3 - Determine your capacity requirements
Define your minimum and maximum capacity requirements. Be sure to select the capacity over the maximum operating load and determine all extraneous loads and moments before selecting the capacity. Note: if the correct load is not selected, extraneous loads and moments increase combined stress which accelerates fatigue and will also affect the performance and accuracy. Most in-line sensors such as an S-Beam load cell are not designed with extraneous load and moment capabilities. For endurance or fatigue applications, try to operate at 50% or lower of the rated capacity or use a fatigue rated sensor.
Step 4 - Define your size requirements
Next you need to define your size requirements (width, weight, height, length, etc.) and specification requirements (output, nonlinearity, hysteresis, creep, bridge resistance, resolution, frequency response, etc.) You also should recognize if your application will be submersible or exposed to water, or will experience cryogenic or high temperatures.
After you've followed the above steps, you'll have a better idea of what load cell you will need. Below are the most common types of load cells for your reference:
In-Line Load Cells - Most commonly referred to as an in-line load cell or a canister-style load cell with male threads. This style of sensor can be used in both tension and compression loading applications. In-line load cells offer high accuracy and high stiffness with minimal mounting clearance needed. They are great for endurance, off-center, and press applications.
Load Button Load Cells - These load cells have a single flat, raised surface (aka a button) where the compressive force is applied. What's impressive about load buttons is their low profile design. As small as they are, they are known for their robustness and are used in fatigue applications.
S-Beam Load Cells - With other names including Z-Beam or S-Type load cells, the S-Beam is a tension and compression sensor with female threads for mounting. Sporting high accuracy and a thin, compact profile, this load cell type is great for in-line processing and automated control feedback applications.
Thru-Hole Load Cells - Also known as donut load cell or washer load cell, these sensors traditionally have a smooth inner diameter used to measure compressive loads that require a rod to pass through its center. One of the primary uses of this sensor type is to measure bolt loading.
Pancake Load Cells - Pancake, canister-style, or universal load cells have a central threaded hole for measuring loads in either tension or compression. These load cells are used in applications needing high endurance, high fatigue life, or high-capacity in-line measurements. They are also highly resistant to off-axis loading.
Rod-End Load Cells - This load cell type offers one male thread and one female thread for mounting. The male and female thread combination is well suited in applications where you need to adapt a sensor into an existing fixture.
Consider purchasing a full system:
If you need an instrument for your application, be sure to select one instrument at the same time you select your sensor. Once you've chosen an instrument to go with your sensor, we recommend choosing a full system calibration. A full system calibration ensures that your sensor and instrument are fully compatible so that you can easily plug and play.
Remember, these tips are guidelines to help point you in the right direction when selecting your sensor. It is crucial to find a sensor manufacturer that has the proven experience and resources to support your needs. Find out if the company has worked with similar applications in the past. If it is a new application in which there is no precedence, select a company that has a reputation for taking on these new challenges and would be able to work with you every step of the way from design through to manufacturing and implementation. If you require a custom product, note that your expected delivery time will increase by at least one month.