As with any scientific instrument, you want maximum accuracy and precision with your force tester.
As with any scientific instrument, though, there is always the unfortunate factor of uncertainty – or, “How sure am I that the results I’m getting are correct?”
Even small errors can have big impact. When force-testing a material or product, there is such a small margin for error that uncertainty can throw off the complete evaluation of the test subject – or, worse, put you back to square one.
Reducing uncertainty with your force tester is a function of identifying the various sources of uncertainty in your force-testing process. If you can ID and isolate these sources, you can become more confident in your test results and be able to trust your measurements more explicitly.
Here are factors that contribute to uncertainty and how to handle them.
The Force Tester Itself
It goes without saying that test results are only as accurate and correct as the force tester can allow.
In other words, the force tester itself is a big determining factor of whether or not your results will be certain or uncertain, correct or incorrect, accurate or inaccurate.
As the nerve center of the force measurement process, the force tester has to be appropriate for the job. In turn, the operator needs to know the specs of the force tester – namely, the instrument’s uncertainty of measurement within a certain plus-minus tolerance and the range of minimum/maximum performance (such as within a particular high/low temperature range).
Fixtures that Affect Alignment
Another factor that contributes to uncertainty are the force-testing fixtures that impact the alignment of the specimen being tested. These fixtures include couplings, grips, and adaptors that help you put the specimen into place. The wrong fixtures – or fixtures that are improperly aligned – can negatively affect the results of your tests.
The Operating Environment
Lastly, the operating environment can affect how you measure and handle uncertainty.
The operating environment includes the environment itself – temperature, humidity, vibrations, electric discharge, air movement, etc. – as well as the operator. Human error is a key contributor to test results being skewed or inaccurate, since we can’t possibly have the same accuracy level as a machine. Humans are also subject to things computers aren’t: fluctuations in performance and attention caused by external factors like fatigue, mood, stress, etc.
The way to solve both problems is to have a thorough, tested program in place to ensure consistency. Use checklists and procedures designed to deliver the same performance with each test, no matter who is performing the test. Create a process by which the environment is kept stable and consistent, with exact specifications for all the environmental variables mentioned above.
Overall, uncertainty can be reduced by not only choosing the right force tester, but also developing a program focused on consistency in all phases of the testing process. Paying close attention to the variables that impact uncertainty and accuracy is the best way to have control over what happens in the lab.