This may be the last version of our Newsletter in this format. This newsletter discusses our Portable Calibrator, LAC and has an article on measurement risk.
Features: New Calibration Certificates and QR Codes; Top 3 ASTM E74 Calibration Mistakes; Upcoming Events – Announcements and Dates
Features: Designing Force Adapters for Calibration; Quick Change Tension Adapters for Calibrating Machines; Upcoming Events – Announcements and Dates; Meet Our Staff - James Wagner, Chief Engineer
Features: 2-Bar Versus 3-Bar Universal Calibrating Machines; ASTM E74 Calibration – Simplified step-by-step instructions; Upcoming Events – Announcements and Dates
Features: Tips from the Cal Lab - SPC – Statistical Process Control in the lab; Good Measurement Practice – Keep your system in control with a 5 in 1 solution; Calibration Intervals – by Phil Smith; Upcoming Events – Announcements and Dates
Features: Load Cell Troubleshooting – Morehouse 7 Step Load Cell Troubleshooting Guide; Potential Measurement Error – Tension Links; Meet the Morehouse Staff – Barry Cook (Lab); Training Workshop – Announcements and Dates
Features: Lean Tips – Setup Reduction; Potential Measurement Error – Unbolting Load Cells May Not Product Repeatable Results; Meet the Morehouse Staff – William Lane (Design Engineer); “Specifying Accredited Services” – Column by Phil Smith
Features: Lean Tips - 5S or 6S; Potential Measurement Error - 4 wire versus 6 wire; Meet the Morehouse Staff - Brian Ruppert (Machine Shop Supervisor); "Single Measurement Bliss" - Column by Dilip Shah discussing the problems with a single measurement
Features: Tips from the calibration lab - Point of Use to Save Time; Potential Measurement Error - Loading Through Bottom Threads in Compression; History of Morehouse - A detailed history from the 1920's through 2015; Oops! I severed my Cable Again - An article about switching cables
Converting a mV/V load cell signal into Engineering Units: Why this may be the most accurate and cost-effective way to use a calibration curve.
Why read this article? If you use load cells, the chances are that someone is setting them up using a 2 point or 5 point span calibrations. This type of setup often has high errors. This article discusses a more accurate way to eliminate the majority of these errors. Morehouse goes on to explain what mV/V is and why using a calibration curve may be the most accurate method for displaying the results in engineering units such as lbf, kgf, N.
Several organizations and publications reference or insist on maintaining a 4:1 Test Uncertainty Ratio (TUR) without understanding the level of risk that they may be subjecting themselves to. The general thought is if the lab performing the calibrations has standards at least four times better then what they are calibrating that everything is good. This paper discusses TUR, PFA Risk, and why the location of the measurement matters. We will discuss two managed risk guard banding methods (5 & 6) found in the ANSI/NCSL Z540.3 Handbook. We will show that a 4:1 TUR is not enough and can result in a 50 % risk.
Want to learn more about force measurement errors and the impact the wrong adapters can have? The wrong adapters can produce measurement errors up to 20 times that of when the instrument was calibrated. This technical paper provides greater detail on adapters for compression and tension calibration of load cells, mini load cells, washer load cells, s-beam, tension links, multi-axis, hand-held for gauges and other force measuring instrumentation. It goes into detail about to improve your force calibrations with the proper adapters.
Morehouse has been performing both ASTM E74 and ISO 376 calibrations for more than fifteen years. We have been calibrating in accordance with the ASTM E74 standard since its introduction in 1974, and performing ISO 376 calibrations since sometime in early 2000. Until recently, we assumed that the rest of the world and force community knew that the standards were completely different and that either standard could not be substituted for another. This paper explains those differences in more detail.
Measurement decision risk as probability that an incorrect decision will result from a measurement. Are you telling your customers instrument passes without considering measurement uncertainty? If taken to court, are your measurement defensible? This paper examines the proper way to make statements of compliance.
Having troubles understanding measurement uncertainty and how to put together a budget? This paper examines all of the components required to put together a full calibration and measurement capability (CMC) reviewed by Accreditation Bodies for your scope. This is a guide to calculating force measurement uncertainties and was published in Cal Lab magazine.
Article written by Henry Zumbrun for Cal lab Magazine.
What you need to know about dual range calibrations. Article from Test Magazine May 2016 issue.
Article in test magazine from Oct-Nov 2015 issue.
There is not a difference in repeatability and reproducibility between a 2 bar and a 3 bar Universal Calibrating Machine
Written and published in Cal Lab magazine April 2016
In the last Back-to-Basics blog, I covered How a Transducer Measures Force. As I continue to cover basic concepts for beginners, this blog will cover the terms compression and tension and how they relate to force calibration.
In our first Back-to-Basics blog, I covered Force Calibration and its Importance. As I continue to cover basic concepts for beginners, this blog will define a transducer and describe how one is used to measure compression and tension force.
For the start of the new year and our 101st year in business, we thought about the tremendous amount of knowledge Morehouse Instrument Company has shared throughout the years with blogs, technical papers, and webinars. This education aligns with our purpose, to create a safer world by helpings companies improve their force and torque measurements. When I looked through all these resources, not many of them speak to the beginner level or the importance of understanding the basics. So, I am starting a Back-to-Basics series of blogs with “Force Calibration and its Importance.” Throughout 2021 I will continue to cover basic concepts with additional topics for beginners.
Centering a load cell is critical to obtaining the correct line of force and reducing calibration errors. An alignment plug along with an adapter plate can be used to center a load cell, whether it is a reference standard in a calibrating machine or a unit under test. Morehouse shows the proper way to use alignment plugs to reduce operator error and setup costs.
Reporting the Expanded Uncertainty of the measurement is a requirement of ISO/IEC 17025, and likely always will be. This post examines the methods Morehouse uses which comply with ILAC-P14, JCGM 100:2008, and ANS/NCSLI Z540.3
This article seeks to explain what coefficients do, how they are used, and the residual errors. We examine what curve fitting does for force-measuring instrumentation when calibrated by standards such as ASTM E74 and ISO 376.
Several calibration laboratories claim traceability to NIST which is not correct. The correct terminology is if using NIST to perform the calibration is traceable to SI Units through NIST
ASTM E74 and Accuracy Statements: Why An Accuracy Statement Does Not Belong on Every Calibration Certificate
When reporting measurement error, we have observed numerous users taking the liberty of standing behind common misconceptions that a measurement is as accurate from which it came, or they adopt a fallback position of saying the calibration of the force-measuring instrument needs to be four times more accurate than the force-measuring instrument being calibrated. When these types of questions are raised, we typically observe best practices falling short of the actual intent of the ASTM E74 standard. This post examines how to use the ASTM E74 calibration certificate properly when accessing the system accuracy.
Specifying a Tolerance, the Difference Between Percentage of Indicated Value vs % of Full-Scale Output.
I assume almost everyone has seen an accuracy specification. This article questions those specifications as several manufacturers do not let you know what criteria they used to set the specification. This can result in severe under-reporting of measurement uncertainty and lead to catastrophic failures. hashtag#better hashtag#force hashtag#measurement starts with educating our customers on what matters and how to make better measurements